JP4034458B2 - Self-excited AC / DC converter control device and circuit breaker circuit control device - Google Patents

Description

【００５７】
その結果がレベル検出器３５２に与えられ、一定のレベル、例えば変換器定格電流の８０％といった値を超えた場合に「１」が出力され、ＡＮＤ回路３５３に入力される。一方、遮断器状態監視装置２４から与えられた信号もＡＮＤ回路３５３に入力され、両方の信号が「１」となった場合にＡＮＤ回路３５３の出力が「１」となり積分器３５４に与えられる。
【００５８】
ここで、遮断器状態監視装置２４は交流系統の遮断器２１、２１’が三相開放となった場合に「１」を出力するものである。積分器３５４ではＡＮＤ回路３５３の出力を積分し、その出力がレベル検出器３５５に与えられ、一定値を超えた場合には、スイッチ回路３２に対して投入指令信号が与えられる。
【００５９】
一方、図１において、スイッチ回路３４も通常時は開放状態であり、遮断器状態監視装置２４の出力が投入指令信号として与えられると、スイッチ回路３４が閉じ、その出力は電圧制御要素３６に与えられる。電圧制御要素３６は比例積分回路で構成され、その出力は加算器３７、３７’に与えられて、加算器３０、３０’の出力にさらに加算される。その結果得られた値が、補正された制御率Ｃｍｄ’、Ｃｍｑ’としてＰＷＭ制御回路１５に入力される。ＰＷＭ制御回路１５では、それらの値と位相検出器１６から得られた交流系統母線１の電圧位相θｖに基づいて自励式交直変換器３に対するパルス信号を発生する。
【００６０】
次に、自励式交直変換器制御装置４７の動作を説明する。まず、通常時は交流系統の遮断器２１、２１’は投入されているので、自励式交直変換器３は複数の発電機２２と接続された状態であり、例えば中央給電指令所などから与えられた有効電力指令値Ｐｒｅｆ、無効電力指令値Ｑｒｅｆどおりの有効電力と無効電力とを交流系統母線１に対して供給あるいは吸収しながら運転する。自励式交直変換器の近傍の負荷系統１８や調相設備１９に対しては複数の発電機２２と自励式交直変換器３の両方から有効電力および無効電力が供給されるため、自励式交直変換器３の有効電力や無効電力の出力は必ずしも負荷系統１８や調相設備１９の容量と一致していなくても、交流電圧が定格値付近に保たれ安定に運転できる。
【００６１】
一方、遮断器２１、２１’が投入状態なので遮断器状態監視装置２４の出力はオフであり、この信号により投入が行われるスイッチ回路２８、２８’、３４はすべて開放されている。また、遮断器状態監視装置２４の出力信号により入力値を事前の値に保持する信号保持回路２５、２５’は動作しておらず、交流電流制御回路１３から与えられる制御率Ｃｍｄ、Ｃｍｑがそのまま出力されている。以上の結果、加算器３０、３０’、３７、３７’に与えられる電流制御要素２９、２９’、電圧制御要素３６の出力はすべて零で、かつ信号保持回路２６、２６’の出力はそれぞれ入力値と等しい。こうした運転状態は、図３０に示す従来の自励式交直変換器制御装置を使用した場合と全く同じである。
【００６２】
次に、交流系統において遮断器２１が三相開放となった場合で、かつ自励式交直変換器３に接続される負荷系統１８や調相設備１９がその自励式交直変換器３の容量に比べ小さい場合の動作を説明する。
【００６３】
遮断器２１が三相開放となることにより、交流系統母線１およびそれに接続される自励式交直変換器３、負荷系統１８、調相設備１９は、発電機２２を含む電源系統２３と完全に切り離された状態となる。従って、負荷系統１８や調相設備１９に対しては、自励式交直変換器３から適切な有効電力および無効電力を供給する必要があるが、通常運転時に使用されている有効電力設定値Ｐｒｅｆ、無効電力設定値Ｑｒｅｆは、接続された負荷系統１８や調相設備１９の大きさに見合った値ではないにもかかわらず、自励式交直変換器３は遮断器２１の開放後もそれらの設定値どおりの有効電力および無効電力を供給あるいは吸収し続けるため、交流過電圧や電圧低下が発生し、安定な運転が行えなくなることがある。
【００６４】
そこで、第１の実施の形態のおける自励式交直変換器制御装置４７では、遮断器２１が三相開放となったことを遮断器状態監視装置２４により検出し、スイッチ回路２８、２８’、３４を投入す。また、信号保持回路２５、２５’ではそれぞれの出力値を保持指令が与えられた時点での値に保持する。
【００６５】
一方、過電流検出器３５では、接続される負荷系統１８や調相設備１９の容量が小さいので、レベル検出器３５２は動作せず、積分器３５３、レベル検出器３５４の出力も「０」でありスイッチ回路３２に対する投入指令は与えられない。このため、加算器３３の出力は電圧設定値Ｖｒｅｆと等しくなる。
【００６６】
これにより、信号保持回路２５、２５’の出力は一定となり、また交流系統母線１の電圧Ｖａｃが交流設定値Ｖｒｅｆよりも大きくなると加算器３３’の出力が負となり、比例積分回路で構成される電圧制御要素３６の出力も負となる。この値が加算器３７、３７’に与えられて、補正された制御率Ｃｍｄ’、Ｃｍｑ’は補正前の値より小さくなる。
【００６７】
制御率Ｃｍ(Ｃｍｄの２乗とＣｍｑの２乗の和の平方根）は、自励式交直変換器３の交流出力電圧の大きさに相当する値である。従って、Ｃｍｄ’、Ｃｍｑ’が小さな値になることにより、自励式交直変換器３の交流出力電圧が小さくなる。交流系統母線１には他に電源が接続されておらず、母線電圧の値は自励式交直変換器３の出力電圧により決まるので、上記のように自励式交直変換器３の出力電圧が小さくなれば交流系統母線１の電圧も小さくなる。逆に交流系統母線１の電圧の大きさＶａｃが加算器３３の出力である電圧設定値Ｖｒｅｆより小さくなると、Ｃｍｄ’、Ｃｍｑ’の値が大きくなるよう補正が行われ、自励式交直変換器３の出力電圧が大きくなり、交流系統母線１の電圧も大きくなる。
【００６８】
このように動作することにより、交流系統母線１の電圧はその電圧設定値Ｖｒｅｆと等しくなるよう制御され、自励式交直変換器３の有効電力および無効電力出の力は、自動的に接続された負荷系統１８や調相設備１９の容量に見合った値となる。交流電流制御回路１３の出力は信号保持回路２６、２６’により固定されているので、交流電流制御回路１３に与えられる通常運転時の有効電力設定値Ｐｒｅｆ、無効電力設定値Ｑｒｅｆ、および交流電流制御回路１３の動作は無視される。
【００６９】
さらに、第１の実施の形態では、自励式交直変換器３の出力が安定化するように交流電流制御を行っている。自励式交直変換器３が突然交流電源と切り離された状態では、有効電力成分や無効電力成分のそれぞれの適切な電流設定値が不明なので、第１の実施の形態では、ｄ軸電流検出値Ｉｄに対し１次遅れ回路２６を介した値をｄ軸電流設定値、ｑ軸電流検出値Ｉｑに対し１次遅れ回路２６’を介した値をｑ軸電流設定値として使用する。
【００７０】
これは、前述したように、通常運転時の交流電流制御回路１３の出力であるＣｍｄ、Ｃｍｑを固定し、それに対して交流電圧制御で補正をかけることにより、出力電流Ｉｄ、Ｉｑは自動的に負荷系統１８や調相設備１９とバランスした値になるので、その値自体を電流設定値とするものである。
【００７１】
遮断器２１の三相開放時にはスイッチ回路２８、２８’が投入され、電流制御要素２９、２９’が動作して、変換器出力電流の有効電力成分Ｉｄ、無効電力成分Ｉｑが、それぞれ１次遅れ回路２６、２６’を介した振動成分の少ない値に追従するような補正信号が出力され、加算器３０、３０’に与えられることにより、Ｃｍｄ’、Ｃｍｑ’が有効電力や無効電力の振動を抑制するように補正される。以上の作用は、公知文献（平成９年電気学会／電力・エネルギー部門大会Ｎｏ．３２０「直流連系用自励式交直変換器による単独運転方式の検討（１）」に示されている。
【００７２】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【００７３】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は、負荷系統１８や調相設備１９が小さい場合と同様である。動作が異なるのは過電流検出器３５およびスイッチ回路３２である。大きな容量の負荷系統１８や調相設備１９に有効電力および無効電力を供給しようとすると、自励式交直変換器３の出力電流が増大し、過電流検出器３５における演算回路３５１の出力が大きくなってレベル検出器３５２が動作する。
【００７４】
また、遮断器２１が三相開放状態であり遮断器状態監視装置２４の出力も「１」状態なので、ＡＮＤ回路３５３の出力も「１」となり、この状態が一定時間続くと積分回路３５４の出力値が増加しレベル検出器３５５のレベル設定値を超え、スイッチ回路３２に投入指令信号が与えられる。
【００７５】
これにより、加算器３３に電圧設定値の低減幅ΔＶｒｅｆが負の符号で加算され、加算器３３’で電圧検出値Ｖａｃと突き合わせが行われる最終的な電圧設定値は（Ｖｒｅｆ−ΔＶｒｅｆ）となる。従って、交流系統母線１の電圧は、電圧制御要素３６により、通常よりもΔＶｒｅｆだけ低下した値になるよう自励式交直変換器３の制御が行われる。その他の作用は負荷系統１８や調相設備１９の容量が小さい場合と同様である。
【００７６】
ここで、交流電圧を下げることにより自励式交直変換器３の出力電流値を低減する原理について、図３により説明する。図３で交流系統母線電圧をＶｓ、負荷系統のインピーダンスをＺとすると流れる電流Ｉは、下記の（２）式で与えられる。
【００７７】
Ｉ＝Ｖｓ／Ｚ …（２）
また、母線電圧Ｖｓは自励式交直変換器３の出力電圧Ｖｉを大きくすれば大きくなり、小さくすれば小さくなる。負荷系統容量が大きい、すなわちインピーダンスＺが小さいと、（２）式の電流Ｉが大きくなり過電流が発生する。この過電流Ｉを抑制するには、インピーダンスＺを大きくするか、母線電圧Ｖｓを小さればよい。第１の実施の形態では、自励式交直変換器３の出力電圧Ｖｉを下げることにより母線電圧Ｖｓを下げて、電流Ｉを低減し過電流が抑制される。
【００７８】
電圧を長時間低下させたままの状態で運転すると停電などが発生する可能性があるので、最終的には負荷系統遮断あるいは調相設備のトリップが必要になるが、そうした操作を行うまでの間、高速に動作する自励式交直変換器３の制御により過電流を抑制すれば、停電させる負荷系統を必要最小限にすることができる。
【００７９】
図４に、第１の実施の形態を適用した場合のディジタルシミュレーション結果の波形を示す。このシミュレーションは、自励式交直変換器３が交流電源と繋がった状態で有効電力１００％の逆変換器運転（交流側へ電力供給）している状態から、電源と切り離され自励式交直変換器３の定格の１．５倍の容量のキャパシタが接続された状態になったときの変換器出力電流と交流系統母線１の母線電圧の波形を示したものである。
【００８０】
図４（ａ）は、制御の切り換えを行った後に、過電流を検出して交流電圧設定値Ｖｒｅｆを通常の１００％から７０％へ低減した場合の特性を示しており、図４（ｂ）は、制御の切り換えのみを行って交流電圧設定値Ｖｒｅｆの低減を行わない場合の特性である。交流電圧設定値Ｖｒｅｆを低減することによる過電流抑制効果があることが判る。
【００８１】
以上述べたように、第１の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の母線電圧を一定に維持するよう制御する。
【００８２】
これにより、自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力でき、さらに出力電流の有効電力成分や無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。さらに、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく、その変換器出力が過電流になる場合には、交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【００８３】
次に、本発明の第２の実施の形態を説明する。図５は本発明の第２の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図である。この第２の実施の形態が図１に示した第１の実施の形態と異なる点は、制御の切り換え指令信号として交流系統母線１の電圧の周波数変化の検出信号を使用するようにした点である。
【００８４】
すなわち、図１における遮断器状態監視装置２４の代わりに、系統状態監視装置として、交流電圧検出器３８、周波数偏差検出器３９、レベル検出器４０、リセット付き積分器４１、レベル検出器４２とを設ける。交流電圧検出器３８により交流系統母線１の母線電圧を検出し、周波数偏差検出３９では、検出した交流電圧の周波数と予め設定した一定の周波数値（例えば、交流系統の定格周波数）との偏差分を演算する。レベル検出器４０では与えられた周波数偏差が一定のレベルを超えている場合に「１」を出力し、超えていない場合には「０」を出力してリセット付き積分器４１に与える。リセット付き積分器４１では入力値が「１」の場合はそれを積分し、入力値が「０」となった場合には出力をゼロリセットする。レベル検出器４２ではリセット付き積分器４１から与えられた値が予め設定された一定値を超えた場合には、制御切り換え指令信号としてスイッチ回路２８、２８’、３４に投入指令を、信号保持回路２５、２５’に対して信号保持指令を与える。その他の部分の構成は、図１に示す第１の実施の形態と同じである。
【００８５】
次に動作を説明する。通常時は交流系統の遮断器２１、２１’は投入されているので、交流系統母線１は電源系統２３の発電機２２と接続された状態であり、交流系統母線１の周波数も発電機２２の回転速度により決まるので、ほぼ定格値に保たれる。これにより周波数偏差検出器３９の出力値は小さな値となり、レベル検出器４０、リセット付き積分器４１、レベル検出器４２の出力はそれぞれ「０」である。従ってスイッチ回路２８、２８’、３４に投入指令は与えられず各スイッチは開放状態となる。また、信号保持回路２５、２５’に保持指令信号は与えられないので、信号保持回路２５、２５’は入力値Ｃｍｄ、Ｃｍｑをそのまま出力する。こうした運転状態は、図３０に示す従来の自励式交直制御装置を使用した場合と全く同じである。
【００８６】
次に、遮断器２１が三相開放となった場合の動作を説明する。遮断器２１が三相開放となることにより、交流系統母線１およびそれに接続される自励式交直変換器３、負荷系統１８、調相設備１９は、発電機２２を含む電源系統２３と完全に切り離された状態となる。このため、交流系統母線１の周波数を決める要素がなくなり周波数が変化する。また第１の実施の形態で説明したのと同様、負荷系統１８や調相設備１９の容量と自励式交直変換器３の出力とのバランスが崩れ、交流過電圧や電圧低下が発生し、安定な運転が行えなくなることがある。
【００８７】
そこで、第２の実施の形態では、交流系統母線１の母線電圧の周波数が変動することを検出し、自励式交直変換器３が接続される交流系統の発電機２２が切り離された状態になったと判定する。すなわち、交流系統母線１の母線電圧の周波数が変動すると周波数偏差検出器３９の出力値が大きな値となり、これによってレベル検出器４０の出力が「１」となる。発電機２２が切り離された状態が継続すればこの状態が続くので、積分器４１の出力値が時間と共に大きくなり、一定時間が経過するとその値がレベル検出器４２の設定レベルを超え、レベル検出器４２は「１」を出力する。この信号が、スイッチ回路２８、２８’、３４にそれぞれ投入指令として与えられ、また信号保持回路２５、２５’に対しては保持指令信号とした与えられる。さらに、接続された負荷系統１８や調相設備１９の容量が大きい場合には、過電流検出器３５が動作してスイッチ回路３２が投入され、これらの動作により、ＰＷＭ制御回路１５へ与えられる制御率信号Ｃｍｄ’、Ｃｍｑ’は、第１の実施の形態の場合と同じように動作する。
【００８８】
この第２の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の母線電圧の周波数が継続して通常運転時の値から大きく逸脱したことを条件にして、交流電圧を一定に維持するよう制御する。これにより自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力できる。さらに、出力電流の有効電力成分および無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。さらに、接続された負荷系統や調相設備が変換器の容量より大きく、変換器出力が過電流になる場合には、交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【００８９】
次に、本発明の第３の実施の形態を説明する。図６は、本発明の第３の実施の形態に係わる自励式交直変換器制御装置４７の構成図である。この第３の実施の形態は、図１に示すの第１の実施形態に係る自励式交直変換器制御装置３から、スイッチ回路３２と加算器３３とを削除し、過電流検出器３５の出力をＰＷＭ制御回路１５に直接与える構成としたものである。その他の構成は、図１に示した第１の実施の形態と同一であるので、同一要素には同一符号を付しその説明を省略する。
【００９０】
第３の実施の形態における過電流検出器３５は、自励式交直変換器３の交流出力電流が一定時間以上継続して所定値を超えたときは、ＰＷＭ制御回路１５におけるパルス幅制御で使用する正弦波信号の波高値に対する正弦値を通常より小さな値にする。これにより、自励式交直変換器３が発電機２２と突然切り離された状態になった場合も、交流過電圧や電圧低下を防止し、接続された負荷系統や調相設備に見合った値の有効電力および無効電力を供給しながら安定に自励式交直変換器の運転を継続する。
【００９１】
図７は、第３の実施の形態におけるＰＷＭ制御回路１５の内部構成の構成図である。制御率Ｃｍｄ’、Ｃｍｑ’が演算回路１５１に入力され、ＰＷＭ制御で使用する正弦波信号の波高値Ｃｍ（Ｃｍｄ’の２乗とＣｍｑ’の２乗との平方根）が演算され、下記（３）式により、交流系統母線１の位相θｖに対する相対的な位相角φに変換される。
【００９２】
φ＝ｔａｎ^-1（Ｃｍｑ’／Ｃｍｄ’） …（３）
正弦波信号の波高値Ｃｍは、リミッタ回路１５２を介して正弦波発生回路１５３へ与えられ、位相角φは加算器１５４で交流系統母線位相θｖに加算されて瞬時変化する絶対位相（θｖ＋φ）に変換されて正弦波発生回路１５３へ与えられる。正弦波発生回路１５３では、下記（４）式により瞬時変化する正弦波信号を発生する。
【００９３】
Ｃｍ（ｔ）＝Ｃｍ・ｃｏｓ（θｖ（ｔ）＋φ） …（４）
一方、搬送波発生回路１５５では、交流系統母線１の位相θｖに同期した波高値一定の搬送波を発生する。それぞれの波形がレベル比較回路１５６へ与えられ、その大小関係によってオンパルスまたはオフパルスを発生し、自励式交直変換器３の半導体素子のオン／オフを行う。
【００９４】
ここで、リミッタ回路１５２で使用するリミット値は、通常、一定の値であり、搬送波の波高値の９０〜９５％程度の値である。このリミッタは正弦波波高値が大きくなり、搬送波波高値と同じかそれ以上になると正常なスイッチングが行えなくなるために設けられているものである。
【００９５】
図８にＰＷＭ制御の各波形とスイッチングタイミングの関係を示す。搬送波は正弦波より高い周波数で波高値一定の三角波として発振する。正弦波は変換器出力電圧の基本波成分に相当する信号で、発生させたい出力電圧に応じた波高値を使用する。正弦波と搬送波との突き合わせを行って、その大小関係によりスイッチングタイミングを決める。
【００９６】
ここで、正弦波の波高値が搬送波よりも小さい場合には、図８（ａ）に示すように、例えば搬送波が正弦波の３倍の周波数であれば正弦波１サイクル間に各３回のオン／オフが行われる。次に、正弦波の波高値が搬送波よりも大きくなると、図８（ｂ）のようにスイッチングがオンオフ各１回ずつとなり正常な動作が行われない。そこで、正弦波の波高値に搬送波よりも若干小さな、例えば搬送波波高値の９０〜９５％といった値のリミットをかけ、図８（ｃ）のような波形として各３回のスイッチングを行うよう制御する。
【００９７】
ここで図７に示す、ＰＷＭ制御回路１５ではスイッチ回路１５７を設け、入力端子の一方には通常時使用する搬送波波高値の９０〜９５％程度の値をＣｍａｘ１として与えておく。他方の入力端子にはそれより小さな例えば搬送波の７０％といった値をＣｍａｘ２として与えておく。過電流検出器３５により過電流が検出された場合には、スイッチ回路１５７を切り換えてＣｍａｘ２を選択し、それをリミッタ回路１５２で使用するリミット値とする。
【００９８】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は、第１の実施形態と全く同じである。ＰＷＭ制御回路１５では正弦波信号に対するリミット値として搬送波の９０〜９５％程度の値であるＣｍａｘ１を使用している。
【００９９】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が変換器容量に比べ大きい場合の動作を説明する。
【０１００】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９が小さい場合と同様である。動作が異なるのは過電流検出器３５およびＰＷＭ制御回路１５内のスイッチ回路１５７、リミッタ回路１５２である。大きな容量の負荷系統１８や調相設備１９に有効電力および無効電力を供給しようとすると変換器出力電流が増大し、図２における過電流検出器３５のレベル検出器３５２が動作する。また遮断器状態監視装置２４の出力も「１」状態なのでＡＮＤ回路３５３の出力も「１」となり、この状態が一定時間続くと積分回路３５４の出力値が大きくなってレベル検出器３５５のレベル設定値を超え、ＰＷＭ制御回路１５内のスイッチ回路１５７に切り換え指令信号が与えられる。
【０１０１】
これにより、リミッタ回路１５２で使用するＰＷＭ正弦波信号波高値に対するリミット値が通常時よりも小さな値Ｃｍａｘ２に切り換えられ、正弦波発生回路１５３により発生する正弦波信号は小さな値に制限される。この信号は変換器出力電圧に比例するため、変換器出力電圧が小さな値に制限される。
【０１０２】
ここで、第１の実施の形態で説明したように、交流電圧を下げることにより変換器出力電流値を低減することができる。電圧を長時間低下させたままの状態で運転すると停電などが発生する可能性があるので最終的には負荷系統１８の遮断あるいは調相設備１９のトリップが必要になるが、そうした操作を行うまでの間、高速に動作する自励式交直変換器３の制御により過電流を抑制すれば、停電させる負荷系統１８を必要最小限にすることができる。
【０１０３】
図９に、第３の実施の形態を適用した場合のディジタルシミュレーション結果の波形を示す。このシミュレーションは、自励式交直変換器３が交流電源と繋がった状態で有効電力１００％の逆変換器運転（交流側へ電力供給）している状態から、電源と切り離され自励式交直変換器３の定格の２．５倍の容量のリアクトルが接続された状態になったときの変換器出力電流と交流系統母線電圧との波形を示したものである。
【０１０４】
図９（ａ）は制御の切り換えを行った後に、過電流を検出してＰＷＭ正弦波リミットを通常の９５％から５０％へ低減した場合の特性を示しており、図９（ｂ）は制御の切り換えのみを行ってリミッタ値の低減を行わない場合の特性を示している。これら特性曲線からリミッタ値を低減することによる過電流抑制効果が明かである。
【０１０５】
この第３の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の電圧を一定に維持するよう制御することにより、自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力でき、さらに出力電流の有効電力成分および無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。さらに、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく、変換器出力が過電流になる場合には、交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【０１０６】
なお、第３の実施の形態においても、自励式交直変換器３が交流電源と切り離されたことを検出する手段として、遮断器２１、２１’の状態監視信号を使用する代わりに、周波数変動が一定時間以上継続してある範囲を逸脱したことを検出するようにしても良い。この場合も同様の効果を得ることができる。
【０１０７】
また、図７のＰＷＭ制御回路１５において、リミッタ回路１５２を正弦波発生回路１５３の入力部分に置く代わりに、正弦波発生回路１５３の出力に対して同様のリミッタ回路を設け、スイッチ回路１５７から与えられたリミット値Ｃｍａｘ１またはＣｍａｘ２を使用して正弦波信号の波高値を制限する構成としても同様の効果を得ることができる。
【０１０８】
次に、本発明の第４の実施の形態を説明する。図１０は第４の実施の形態に係わる自励式交直変換器制御装置４７の主要部の構成図である。この第４の実施の形態は、図１に示した第１の実施の形態に係る自励式交直変換器制御装置で、過電流検出器３５の出力をスイッチ回路３２に投入指令信号として与えると共に、第３の実施の形態と同様に、過電流検出器３５の出力をＰＷＭ制御回路１５内のスイッチ回路１５７に対しても切り換え指令として与える構成としたものである。その他の構成は、第１の実施の形態と同一であるので、同一要素には同一符号を付しその説明は省略する。
【０１０９】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は、第１の実施の形態と同じである。
【０１１０】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【０１１１】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９が小さい場合と同様である。負荷系統１８や調相設備１９の容量が小さいときと比べ動作が異なるのは、スイッチ回路３２、加算器３３、３３’、過電流検出器３５およびＰＷＭ制御回路１５内のスイッチ回路１５７、リミッタ回路１５２である。大きな容量の負荷系統１８や調相設備１９に有効電力および無効電力を供給しようとすると自励式交直変換器３の出力電流が増大し、過電流検出器３５が動作してスイッチ回路３２が投入される。
【０１１２】
これにより、交流電圧設定値として使用される加算器３３’に与えられる値が通常時のＶｒｅｆから（Ｖｒｅｆ−ΔＶｒｅｆ）へと低下する。また、過電流検出器３５が動作してＰＷＭ制御回路１５の中のスイッチ回路１５７の切り換えが行われ、リミッタ回路１５２で使われるリミット値が通常のＣｍａｘ１からそれよりも小さな値Ｃｍａｘ２へと切り換えられる。
【０１１３】
これらにより、電圧制御要素３６では交流系統母線１の電圧が定格より小さな値となるような補正制御を行い、さらにＰＷＭ制御回路１５では正弦波信号の波高値がＣｍａｘ２以上にならないよう制限するので、交流系統母線１の電圧を下げ、自励式交直変換器３の出力電流値を低減することができる。
【０１１４】
すなわち、交流電圧を下げて運転するための方策として、第１の実施の形態および第２の実施の形態では交流電圧制御で使用する電圧設定値を低減し、第３の実施の形態ではＰＷＭ正弦波信号の波高値を小さな値に制限するのに対し、この第４の実施の形態では、その両方を行うものである。接続されている負荷系統１８や調相設備１９が全体として容量性、すなわちキャパシタ量が大きい場合には、電圧を下げる方策として交流電圧制御で使用する電圧設定値を低減するのがより効果的であり、逆に接続されている負荷系統１８や調相設備１９が全体として誘導性、すなわちリアクトル量が大きい場合には、電圧を下げる方策としてＰＷＭ正弦波信号を小さく制限する方法がより効果的である。
【０１１５】
このため、自励式交直変換器３の近傍に設置されている調相設備１９がどちらかに集中している場合には、片方の操作で充分な効果が得られるが、いろいろな調相設備１９が設置されている場合には、どちらの特性の調相設備１９にも対応できるように、この第４の実施の形態のように両方の操作を行うと、より電圧低減による過電流抑制の確実性が増す。
【０１１６】
この第４の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の母線電圧を一定に維持するよう制御することにより、自励式交直変換器３に接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力できる。
【０１１７】
さらに、出力電流の有効電力成分および無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。また、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく、自励式交直変換器３の出力が過電流になる場合には、交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【０１１８】
なお、第４の実施の形態においても、自励式交直変換器３が交流電源と切り離されたことを検出する手段として、遮断器２１、２１’の状態監視信号を使用する代わりに、周波数変動が一定時間以上継続してある範囲を逸脱したことを検出するようにしても良い。この場合も同様の効果を得ることができる。
【０１１９】
次に、本発明の第５の実施の形態を説明する。図１１は第５の実施の形態に係わる自励式交直変換器制御装置４７の主要部の構成図である。この第５の実施の形態は、図１０に示す第４の実施の形態に係る自励式交直変換器制御装置に、レベル検出器４３、ＡＮＤ回路４４、ＮＯＴ回路４５、ＡＮＤ回路４６を追加したものである。その他の構成は、図１０に示す第４の実施の形態と同一であるので、同一要素には同一符号を付しその説明は省略する。また、過電流検出器３５の内部構成は図２で説明したのと同じ構成であり、ＰＷＭ制御回路１５の内部は図７で説明したのと同じ構成である。
【０１２０】
レベル検出器４３は、ｄｑ軸変換回路１４の出力で自励式交直変換器３の出力電流の無効電力成分であるＩｑが入力され、それが零よりも大きいか否か、すなわち正の値であるか負の値であるかを判定する。ここで、Ｉｑ＞０の場合は無効電力出力が容量性であることを示し、Ｉｑ＜０の場合は無効電力出力が誘導性であることを示している。
【０１２１】
Ｉｑ＞０の場合（容量性の場合）は、レベル検出器４３は「１」を出力しＡＮＤ回路４４とＮＯＴ回路４５に入力する。ＮＯＴ回路４５では１／０信号の反転を行いＡＮＤ回路４６へ与える。一方、過電流検出器３５で過電流を検出すると、信号「１」がＡＮＤ回路４４、ＡＮＤ回路４６に与えられ、ＡＮＤ回路４４では入力信号の双方が「１」となった場合、スイッチ回路３２に対し投入指令を与える。ＡＮＤ回路４６では入力信号の双方が「１」となった場合、ＰＷＭ制御回路１５内のスイッチ回路１５７に対し切り換え指令信号を与える。
【０１２２】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は、第４の実施の形態と同じである。
【０１２３】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９の容量が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【０１２４】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９の容量が小さい場合と同様である。負荷系統１８や調相設備１９の容量が大きく自励式交直変換器３の出力が過電流になると、過電流検出器３５の出力が「１」となる。また、調相設備１９としてキャパシタが接続されている場合には出力電流が容量性（進み電流）となり、ｄｑ軸変換回路１４の出力である無効電力成分の電流がＩｑ＞０となる。
【０１２５】
これにより、レベル検出器４３の出力は「１」、それを反転するＮＯＴ回路４５の出力は「０」となり、それぞれＡＮＤ回路４４、４６に与えられる。各ＡＮＤ回路のもう一方の入力信号である過電流検出器３５の出力は「１」になっているので、ＡＮＤ回路４４の出力は「１」、ＡＮＤ回路４６の出力は「０」となる。従って、スイッチ回路３２が投入されて交流電流設定値が低減される。ＰＷＭ制御回路１５内のスイッチ回路１５７の切り換えは行われない。
【０１２６】
一方、調相設備１９としてリアクトルが接続されている場合には、出力電流が誘導性（遅れ電流）となり、ｄｑ軸変換回路１４の出力である無効電力成分の電流がＩｑ＜０となる。これにより、レベル検出器４３の出力は「０」、それを反転するＮＯＴ回路４５の出力は「１」となり、それぞれＡＮＤ回路４４、４６に与えられる。各ＡＮＤ回路４４、４６のもう一方の入力信号である過電流検出器３５の出力は「１」になっているので、ＡＮＤ回路４４の出力は「０」、ＡＮＤ回路４６の出力は「１」となる。
【０１２７】
これにより、ＰＷＭ制御回路１５内のスイッチ回路１５７の切り換えが行われて、ＰＷＭ正弦波信号波高値に対するリミット値が通常より小さな値Ｃｍａｘ２に切り替わりＰＷＭ正弦波が小さな値に制限される。また、図１１のスイッチ回路３２の投入は行われず、交流電圧設定値の切り換えは行われない。
【０１２８】
これらにより、自励式交直変換器３の出力が容量性過電流の場合には、交流系統母線１の電圧が通常より小さな値となるように、電圧制御要素３６で使用する交流電圧設定値の低減を行い、自励式交直変換器３の出力が誘導性過電流の場合には、ＰＷＭ制御回路１５で使用する正弦波信号の波高値に対する制限値を通常より小さな制限値に切り換えるので、自励式交直変換器３の出力の過電流が容量性か誘導性かという性質に応じた適切な方法で交流系統母線１の電圧を下げ、自励式交直変換器３の出力電流値を低減することができる。
【０１２９】
この第５の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の母線電圧を一定に維持するよう制御することにより、自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力できる。
【０１３０】
さらに、出力電流の有効電力成分および無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。また、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく過電流が発生する場合には、交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【０１３１】
なお、第５の実施の形態においても、自励式交直変換器３が交流電源と切り離されたことを検出する手段として、遮断器２１、２１’の状態監視信号を使用する代わりに、周波数変動が一定時間以上継続してある範囲を逸脱したことを検出するようにしても良い。この場合も同様の効果を得ることができる。
【０１３２】
また、自励式交直変換器３の出力電流が容量性であるか誘導性であるかを判定するために、レベル検出器４３に入力する信号として、ｄｑ軸変換回路１４の出力Ｉｑの代わりに１次遅れ回路２６’の出力信号を使用しても同等の効果を得ることができる。
【０１３３】
次に、本発明の第６の実施の形態を説明する。図１２は第６の実施の形態に係わる自励式交直変換器制御装置４７の主要部の構成図である。この第６の実施の形態は、図１に示した第１の実施形態に係る自励式交直変換器制御装置において、スイッチ回路３２’を追加し、スイッチ回路３２、スイッチ回路３２’それぞれに電圧設定値の低減値ΔＶｒｅｆ１、ΔＶｒｅｆ２を与えておき、過電流検出器３５からの別々の投入指令信号ａ、ｂにより投入を行う構成としたものである。その他の構成は図１に示した第１の実施の形態と同一であるので、同一要素には同一符号を付しその説明は省略する。
【０１３４】
また、図１３は第６の実施の形態における過電流検出器３５の内部構成を示すブロック図であり、図２に示す第１の実施形態における過電流検出器３５に対して、レベル検出器３５２’、ＡＮＤ回路３５３’、積分器３５４’、レベル検出器３５５’を追加したものである。レベル検出器３５２と３５２’には、それぞれ異なるレベルの電流値Ｉ１、Ｉ２（Ｉ１＜Ｉ２）を設定しておき、演算回路３５１で得られた電流の大きさが各設定レベルを超えた場合に「１」をＡＮＤ回路３５３、３５３’に与える構成とする。図１３におけるその他の構成は、図２に示す過電流検出器３５と同一であるので、同一要素には同一符号を付しその説明は省略する。
【０１３５】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は、の第１の実施形態と同じである。
【０１３６】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９の容量が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【０１３７】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９の容量が小さい場合と同様である。負荷系統１８や調相設備１９の容量が大きく自励式交直変換器３の出力電流Ｉが、過電流検出器３５のレベル検出器３５２の設定レベルＩ１を超え、レベル検出器３５２’の設定レベルＩ２よりは小さい場合（Ｉ２＞Ｉ＞Ｉ１）、この状態が一定時間継続すると図１３におけるレベル検出器３５５が動作し、出力信号ａが「１」となる。一方、レベル検出器３５２’が動作しないので、レベル検出器３５５’も動作せず、信号ｂは「０」のままである。
【０１３８】
これにより、図１２の第６の実施の形態において、スイッチ回路３２は投入されスイッチ回路３２’は開放のままとなる。スイッチ回路３２が投入されることにより、加算器３３にΔＶｒｅｆ１が負の符号で加算されるので、電圧制御要素３６で使用される交流電圧設定値は、過電流が発生していない場合のＶｒｅｆよりも小さな（Ｖｒｅｆ−ΔＶｒｅ１）という値になり、交流系統母線１の電圧が通常時よりも小さな値となるように制御が行われる。
【０１３９】
負荷系統１８や調相設備１９の容量がさらに大きく、自励式交直変換器３の出力電流Ｉが、過電流検出器３５のレベル検出器３５２の設定レベルＩ１およびレベル検出器３５２’の設定レベルＩ２の両方を超える場合（Ｉ＞Ｉ２＞Ｉ１）、この状態が一定時間継続すると図１３におけるレベル検出器３５５、３５５’の両方が動作し、出力信号ａ、ｂが「１」となる。
【０１４０】
これにより、図１２のスイッチ回路３２、スイッチ回路３２’の両方が投入される。スイッチ回路３２、３２’が投入されることにより、加算器３３にΔＶｒｅｆ１およびΔＶｒｅｆ２が負の符号で加算されるので、電圧制御要素３６で使用される交流電圧設定値は、Ｉ２＞Ｉ＞Ｉ１の場合よりさらに小さな（Ｖｒｅｆ−ΔＶｒｅ１−ΔＶｒｅｆ２）という値になり、交流電圧はさらに低下するように制御が行われる。
【０１４１】
図３で説明したように、自励式交直変換器３の出力電流Ｉは（２）式で与えられる。負荷系統１８や調相設備１９の容量が大きいほどインピーダンス値Ｚが小さくなるため、電流Ｉを一定値以下に抑制しようとする場合には、電圧ＶｓをＺに応じて下げる必要があるが、この第６の実施の形態に係わる自励式交直変換器制御装置を使用すると、負荷系統１８や調相設備１９の容量が大きいほど、小さな値の交流電圧設定値が使われるので、自励式交直変換器３の過電流が適切に抑制される。
【０１４２】
図１４は、第６の実施の形態における自励式交直変換器制御装置で使用する過電流検出器３５の他の一例を示す構成図である。図１４に示す過電流検出器３５は、図２に示した第１の実施の形態に係る過電流検出器３５に対して、レベル検出器３５５”を追加したものである。
【０１４３】
レベル検出器３５５、３５５”には、それぞれ異なるレベルの時限ｔ１、ｔ２（ｔ１＜ｔ２）を設定しておき、積分回路３５４の出力、すなわち過電流がレベル検出器３５２の設定レベルを超えている時間の長さが各設定レベルを超えた場合に「１」を出力する構成とする。
【０１４４】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は、第１の実施の形態と全く同じである。
【０１４５】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９の容量が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【０１４６】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９の容量が小さい場合と同様である。負荷系統１８や調相設備１９の容量が大きく、自励式交直変換器３の出力電流Ｉが過電流検出器３５のレベル検出器３５２の設定レベルを超えた場合、この状態がレベル検出器３５５で設定された時間ｔ１以上継続すると、出力信号ａが「１」となる。
【０１４７】
これにより、図１２に示すスイッチ回路３２が投入され、加算器３３にΔＶｒｅｆ１が負の符号で加算されるので、電圧制御要素３６で使用される交流電圧設定値は、過電流が発生していない場合のＶｒｅｆよりも小さな（Ｖｒｅｆ−ΔＶｒｅ１）という値になり、交流系統母線１の電圧を下げるように制御が行われる。
【０１４８】
電圧低減幅ΔＶｒｅｆ１が過電流抑制に充分なものであれば、この操作により過電流が解消され、図１４のレベル検出器３５２の出力が「０」となる。これにより積分器３５４の出力はそれ以上大きな値にはならない。従って、レベル検出器３５５”は動作せず、交流電圧設定値は（Ｖｒｅｆ−ΔＶｒｅｆ１）の状態で運転が継続される。
【０１４９】
一方、電圧低減幅ΔＶｒｅｆ１が過電流抑制に不充分だと、この操作を行っても過電流状態が継続し、図１４のレベル検出器３５２の出力が「１」のままになる。これにより積分器３５４の出力が増加し続け、レベル検出器３５５”が動作して出力が「１」となり出力信号ｂとして、図１２におけるスイッチ回路３２’に投入指令が与えられる。過電流検出器３５が以上のように動作することにより、交流電圧設定値はさらに低下し、（Ｖｒｅｆ−ΔＶｒｅｆ１−ΔＶｒｅｆ２）の状態で運転が継続される。これにより、負荷系統１８や調相設備１９の容量が大きいほど、小さな値の交流電圧設定値が使われるので、自励式交直変換器３の過電流が適切に抑制される。
【０１５０】
図１５は、本発明の第６の実施の形態に係わる自励式交直変換器制御装置における過電流検出器のさらに別の他の一例を示す構成図である。図１５に示す過電流検出器３５は、図２に示した第１の実施の形態に係る過電流検出器３５に対して、ＡＮＤ回路３５６、積分器３５７、レベル検出器３５８を追加したものである。ＡＮＤ回路３５６にはＡＮＤ回路３５３とレベル検出器３５５の出力が入力され、その結果が積分器３５７、レベル検出器３５８を介して、図１２におけるスイッチ回路３２’に対する投入指令信号ｂとして出力される。
【０１５１】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は第１の実施形態と全く同じである。
【０１５２】
次に、交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９の容量が自励式交直変換器３の容量に比べ大きい場合の動作を説明する。
【０１５３】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９の容量が小さい場合と同様である。負荷系統１８や調相設備１９の容量が大きく、自励式交直変換器３の出力電流Ｉが過電流検出器３５のレベル検出器３５２の設定レベルを超えた場合、この状態がレベル検出器３５５で設定された時間以上継続すると、出力信号ａが「１」となる。
【０１５４】
これにより、図１２のスイッチ回路３２が投入され、加算器３３にΔＶｒｅｆ１が負の符号で加算されるので、電圧制御要素３６で使用される交流電圧設定値は、過電流が発生していない場合のＶｒｅｆよりも小さな（Ｖｒｅｆ−ΔＶｒｅ１）という値になり、交流系統母線１の電圧を下げるように制御が行われる。
【０１５５】
電圧低減幅ΔＶｒｅｆ１が過電流抑制に充分なものであれば、この操作により過電流が解消され、図１５のレベル検出器３５２、ＡＮＤ回路３５３の出力が「０」となる。これにより、ＡＮＤ回路３５６、積分器３５７、レベル検出器３５８の出力も「０」となり、スイッチ回路３２’に対しては投入指令は与えられない。従って、交流電圧設定値は（Ｖｒｅｆ−ΔＶｒｅｆ１）の状態で運転が継続される。
【０１５６】
一方、電圧低減幅ΔＶｒｅｆ１が過電流抑制に不充分だと、この操作を行っても過電流状態が継続し、図１５のレベル検出器３５２の出力が「１」のままになる。これによりＡＮＤ回路３５３、３５６の出力が「１」の状態が継続し、レベル検出器３５８が動作して出力が「１」となり、出力信号ｂとして、図１２におけるスイッチ回路３２’に投入指令が与えられる。過電流検出器３５が以上のように動作することにより、交流電圧設定値はさらに低下し、（Ｖｒｅｆ−ΔＶｒｅｆ１−ΔＶｒｅｆ２）の状態で運転が継続される。これにより、負荷系統１８や調相設備１９の容量が大きいほど、小さな値の交流電圧設定値が使われるので、変換器の過電流が適切に抑制される。
【０１５７】
この第６の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線３の母線電圧を一定に維持するよう制御することにより、自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力できる。
【０１５８】
さらに、出力電流の有効電力成分および無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。また、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく過電流が発生する場合には、その負荷系統１８や調相設備１９の容量に応じた割合で交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【０１５９】
なお、第６の実施の形態においても、自励式交直変換器３が交流電源と切り離されたことを検出する手段として、遮断器２１、２１’の状態監視信号を使用する代わりに、周波数変動が一定時間以上継続してある範囲を逸脱したことを検出するようにしても良い。この場合も同様の効果を得ることができる。
【０１６０】
また、負荷系統１８や調相設備１９の容量に応じた電圧設定値の低減を行うために、過電流の大きさによって値の切り換えを行い、または、過電流の継続時間によって値の切り換えを行うようにしたが、この両方を組み合わせる構成としても同様の効果を得ることができる。
【０１６１】
次に、本発明の第７の実施の形態を説明する。図１６は、第７の実施の形態に係わる自励式交直変換器制御装置４７の主要部の構成図である。この第７の実施の形態は、図６に示した第３の実施の形態に係る自励式交直変換器制御装置において、過電流検出器３５からＰＷＭ制御回路１５へ与える信号をａ、ｂの２通りにしたものである。ここで、過電流検出器３５としては、図１３、図１４、図１５に示すもののうちいずれかを使用する。
【０１６２】
一方、図１７は、図１６に示す第７の実施の形態おけるＰＷＭ制御回路１５の構成図であり、第３の実施の形態における図７に示すＰＷＭ制御回路１５に対して、論理演算回路１５８を追加し、また入力が２端子のスイッチ回路１５７の代わりに、Ｘ、Ｙ、Ｚの３つの入力端子にそれぞれ異なる値の制限値Ｃｍａｘ１、Ｃｍａｘ２、Ｃｍａｘ３（Ｃｍａｘ１＞Ｃｍａｘ２＞Ｃｍａｘ３）が与えられているスイッチ回路１５７’を使用する構成のものである。
【０１６３】
論理演算回路１５８の内部ロジックを図１８に示す。図１８（ａ）に示すように、ＮＯＴ回路１５８Ａには入力信号ｂが、ＡＮＤ回路１５８Ｂには入力信号ａとＮＯＴ回路１５８Ａの出力とが与えられる。さらにＯＲ回路１５８ＣにはＡＮＤ回路１５８Ｂと入力信号ｂとが、ＮＯＴ回路１５８ＤにはＯＲ回路１５８Ｃの出力が与えられる。
【０１６４】
図１８（ｂ）は、入力信号ａ、ｂに対する端子Ｘ、Ｙ、Ｚの選択状態を示したものであり、ＮＯＴ回路１５８Ｄの出力が「１」の場合、スイッチ回路１５７’の端子Ｘ、ＡＮＤ回路１５８Ｂの出力が「１」の場合、スイッチ回路１５７’の端子Ｙ、入力信号ｂの値が「１」の場合、スイッチ回路１５７’の端子Ｚを選択するよう、スイッチ回路１５７’に対して指令を与える。
【０１６５】
次に動作を説明する。通常時、および交流系統において遮断器２１が三相開放となった場合で、自励式交直変換器３に接続される負荷系統１８や調相設備１９が自励式交直変換器３の容量に比べ小さい場合の動作は第３の実施形態と同じである。
【０１６６】
次に、交流系統において遮断器２１が三相開放となった場合で、変換器に接続される負荷系統や調相設備の容量が変換器容量に比べ大きい場合の動作を説明する。
【０１６７】
スイッチ回路２８、２８’、３４および信号保持回路２５、２５’の動作は負荷系統１８や調相設備１９の容量が小さい場合と同様である。負荷系統１８や調相設備１９の容量が大きく、自励式交直変換器３の出力電流Ｉが、図１３、図１４、図１５における過電流検出器３５のレベル検出器３５２の設定レベルを超えた場合、第６の実施の形態で説明したように信号ａが「１」となる。
【０１６８】
さらに、過電流の大きさが大きい場合や、交流電圧設定値をある程度低減しても過電流が充分抑制できない場合には信号ｂも「１」となる。信号ａ、ｂが以上の動作を行うと、図１８（ｂ）に示すように、論理演算回路１５８では、信号ａも信号ｂも「０」、すなわち過電流が発生していないときは、スイッチ回路１５７’の端子Ｘを選択し、信号ａが「１」で信号ｂが「０」すなわち過電流は発生するが、それが図１３のレベル検出器３５２’の設定レベル以下である、または電圧設定値を（Ｖｒｅｆ−ΔＶｒｅｆ１）まで低減することにより過電流が抑制される場合には、スイッチ回路１５７’の端子Ｙを選択し、信号ａも信号ｂも「１」すなわち過電流が発生しそれが図１３のレベル検出器３５２’の設定レベルを超えたとき、または電圧設定値を（Ｖｒｅｆ−ΔＶｒｅｆ１）まで低減しても過電流が抑制されない場合には、スイッチ回路１５７’の端子Ｚを選択するような信号を発生して、スイッチ回路１５７’に与える。
【０１６９】
スイッチ回路１５７’の端子Ｘ、Ｙ、Ｚには、それぞれ通常の運転状態で使用するＰＷＭ正弦波の制限値Ｃｍａｘ１、それより小さなＣｍａｘ２、さらに小さなＣｍａｘ３が与えられているので、ＰＷＭ正弦波の波高値は過電流の大きさに応じた値に制限される。
【０１７０】
図３で説明したように、自励式交直変換器３の出力電流Ｉは（２）式で与えられる。負荷系統１８や調相設備１９の容量が大きいほどインピーダンス値Ｚが小さくなるため、電流Ｉを一定値以下に抑制しようとする場合には、電圧Ｖｓをインピーダンス値Ｚに応じて下げる必要があるが、第７の実施の形態では、負荷系統１８や調相設備１９の容量が大きいほど、ＰＷＭ正弦波の波高値すなわち自励式交直変換器３の出力電圧が小さな値に制限されるので、自励式交直変換器３の過電流が適切に抑制される。
【０１７１】
なお、第７の実施の形態においても、自励式交直変換器３が交流電源と切り離されたことを検出する手段として、遮断器２１、２１’の状態監視信号を使用する代わりに、周波数変動が一定時間以上継続してある範囲を逸脱したことを検出するようにしても良い。この場合も同様の効果を得ることができる。
【０１７２】
また、負荷系統１８や調相設備１９の容量に応じたＰＷＭ正弦波信号波高値リミッタの低減を行うために、過電流の大きさあるいは過電流の継続時間によって低減値の切り換えを行う構成としたが、この両方を組み合わせる構成としても同様の効果を得ることができる。
【０１７３】
また、交流電圧を低減させる手段として、電圧設定値とＰＷＭ正弦波リミット値との両方を低減する、あるいは自励式交直変換器３の出力電流が容量性であるか誘導性であるかによって電圧設定値の低減かＰＷＭ正弦波リミット値の低減かを選択する方式としても同様の効果を得ることができる。
【０１７４】
第７の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、通常運転時は中央給電指令所などから与えられる設定値どおりの有効電力および無効電力を供給あるいは吸収するよう運転を行い、自励式交直変換器３が突然交流電源から切り離された状態になった場合には、交流系統母線１の母線電圧を一定に維持するよう制御することにより、自励式交直変換器３の接続された負荷系統１８や調相設備１９の容量に見合った値の有効電力と無効電力とを自動的に出力できる。
【０１７５】
さらに、出力電流の有効電力成分や無効電力成分に対し、１次遅れを介した値を設定値として出力電流を制御することにより、有効電力や無効電力の変動を抑制し、より安定な運転を継続することができる。
【０１７６】
また、接続された負荷系統１８や調相設備１９が自励式交直変換器３の容量より大きく過電流が発生する場合には、その負荷系統１８や調相設備１９の容量に応じた割合で交流電圧を低め運転するよう自励式交直変換器３を制御することによって過電流を抑制し、自励式交直変換器３を運転継続し、停電を必要最小限にすることができる。
【０１７７】
次に、本発明の第８の実施の形態を説明する。図１９は第８の実施の形態に係わる遮断器回路制御装置の構成図である。
【０１７８】
交流系統母線１には変圧器２を介して自励式交直変換器３が接続されており、自励式交直変換器制御装置４７により制御されて運転が行われる。自励式交直変換器制御装置４７は、第１の実施の形態乃至第７の実施の形態のいずれかのものが適用され、遮断器２１、２１’の開放などにより電源系統２３と切り離された状態になっても自励式交直変換器３は運転され続ける。
【０１７９】
ここで、第８の実施の形態の電力系統では、調相設備１９の接続された変圧器１７の１次側（交流系統母線１側）をＹ結線とし、その中性点と大地間に遮断器４９を介して高調波フィルタ５０を設置する。遮断器４９は通常時は開放状態である。高調波フィルタ５０は、図２０に示すように、キャパシタＣ、リアクトルＬ、抵抗Ｒを組み合わせたもので、図２０（ａ）に示すハイパス型、あるいは図２０（ｂ）に示す同調型の構成である。これらは一般に電力系統で高調波抑制用に使用されるもので、下記の（５）式に示す次数ｎの高調波電流を通過させて高調波電圧を抑制するものである。
【０１８０】
【数２】

【０１８１】
遮断器状態監視装置２４では、遮断器２１あるいは遮断器２１’が三相開放状態になった場合に「１」信号を遮断器制御回路４８へ与える。一方、自励式交直変換器制御装置４７からは自励式交直変換器３が運転中であることの信号を遮断器制御回路４８へ与える。遮断器制御回路４８では、遮断器状態監視回路２４からの信号が「１」で、かつ自励式交直変換器３が運転中であることを条件として、遮断器４９に投入指令信号を与える。
【０１８２】
次に動作を説明する。通常時は交流系統の遮断器２１、２１’は投入されているので、交流系統母線１および自励式交直変換器３、変圧器１７等は複数の発電機２２を含む電源系統２３に接続されている。電源からは三相正弦波の交流電圧が与えられるので、交流系統母線１の高調波電圧は小さい。遮断器状態監視装置２４の出力は「０」なので遮断器制御回路４８は遮断器４９に対して投入指令は与えず、遮断器４９が開放状態で、変圧器１７は１次側中性点非接地の状態で運転される。高調波フィルタ５０は回路から切り離されている。
【０１８３】
次に、自励式交直変換器３が運転中に交流系統において遮断器２１が突然三相開放となった場合の動作を説明する。遮断器２１が開放状態となって、自励式交直変換器３の出力と接続される負荷系統１８や調相設備１９の容量が一時的にバランスがとれなくなることにより、動揺が発生し交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち、正相成分や逆相成分のものについては、自励式交直変換器３がｄｑ軸電流の振動を抑えるよう電流制御を行うことによって抑制される。
【０１８４】
しかし、交流系統母線１の電圧の零相成分の高調波は自励式交直変換器３により抑制することはできない。これは、一般に変圧器の１次側と２次側との零相回路は遮断されており、変圧器２の２次側に接続される自励式交直変換器３によって１次側に接続される交流系統母線１の零相回路には影響を与えることができないためである。従って、発生した零相高調波は漏れキャパシタンスなどを介して循環し、回路の抵抗分によりわずかずつしか減衰しないので継続時間が長い。
【０１８５】
ここで、図１９に示す第８の実施の形態の遮断器回路制御装置では、遮断器状態監視装置２４の出力が「１」となることにより、遮断器制御回路４８から遮断器４９に対して投入指令が与えられる。これにより、高調波フィルタ５０が変圧器１７の１次側中性点に投入される。Ｙ接続の回路の中性点に発生する電圧は零相電圧であり、高調波フィルタ５０が中性点に投入されることによって零相高調波成分の電流が高調波フィルタ５０に流れその抵抗分Ｒのダンピング効果によって零相高調波が解消される。
【０１８６】
図２１は、変圧器中性点に高調波フィルタ５０を投入することによる零相高調波抑制効果をシミュレーションにより検証した結果である。図２１（ａ）は対策なしの場合であり、電源が切り離された後、発生した交流系統母線１の母線電圧の高調波が継続したままである。この場合、零相電圧の周波数をみると３次で振動している。また、自励式交直変換器３の出力ＰＱの振動は収束しており、自励式交直変換器３の運転と交流系統母線１の母線電圧の歪みが無関係であることがわかる。
【０１８７】
図２１（ｂ）は同じケースで、途中で調相用変圧器１７の中性点に３次フィルタを投入した場合である。交流系統母線１の母線電圧の歪みは投入直後から急速に小さくなっており、零相電圧も小さい。一方、自励式交直変換器３の出力は投入なしの場合と全く変わらない。このシミュレーション結果から、零相高調波発生時に中性点へ高調波フィルタ５０を投入することの歪み抑制効果が明かである。また、これによる自励式交直変換器３の運転への影響がないことも確認できている。
【０１８８】
この第８の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、突然交流電源から切り離された状態になった場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を投入するよう、遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１の零相回路に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を常時、回路に接続しておかないので高調波フィルタ５０にかかるストレスを軽減することができる。
【０１８９】
次に、本発明の第９の実施の形態を説明する。図２２は第９の実施の形態に係わる遮断器回路制御装置の構成図である。この第９の実施の形態は、図１９に示した第８の実施の形態が、定常状態において交流系統母線１の接続される電力系統が中性点非接地の場合のものであるのに対し、定常状態において交流系統母線１の接続される電力系統が中性点直接接地の場合のものである。
【０１９０】
図２２において、変圧器１７の中性点には遮断器４９および高調波フィルタ５０と並列に遮断器５２が設置され、その片端は接地されている。遮断器４９は第８の実施の形態と同様に定常時開放状態で遮断器制御回路４８からの指令により投入される。これに対して、遮断器５２は定常時は投入されており、遅延回路５１からの指令信号により開放される。遅延回路５１は遮断器制御回路４８から投入信号を受取り、それを反転させて一定時間遅延させた後、遮断器５２に対して開放指令を与えるものである。
【０１９１】
次に動作を説明する。通常時は交流系統の遮断器２１、２１’は投入されているので、交流系統母線１および自励式交直変換器３、変圧器１７等は複数の発電機２２を含む電源系統２３に接続されている。電源からは三相正弦波の交流電圧が与えられるので、交流系統母線１の高調波電圧は小さい。遮断器状態監視装置２４の出力は「０」なので遮断器制御回路４８は遮断器４９に対して投入指令は与えず、遮断器４９が開放状態である。一方、遮断器５２は投入状態なので変圧器１７は１次側中性点直接接地の状態で運転される。高調波フィルタ５０は回路から切り離されている。
【０１９２】
次に、自励式交直変換器３が運転中に交流系統において遮断器２１が突然三相開放となった場合の動作を説明する。遮断器２１が開放状態となると、第８の実施の形態の場合と同じように、交流系統母線１の母線電圧の零相成分の高調波は、自励式交直変換器３により抑制することができず歪みが継続する。中性点が接地されているため非接地に比べ高調波電圧は小さいが、変圧器インピーダンスなどが零相インピーダンスの一部として作用するため無視できない程度の高調波電圧が発生する。発生した零相高調波は漏れキャパシタンスなどを介して循環し、回路の抵抗分によりわずかずつしか減衰しないので継続時間が長い。
【０１９３】
そこで、第９の実施の形態では、遮断器状態監視装置２４の出力が「１」となることにより、遮断器制御回路４８から遮断器４９に対して投入指令が与えられる。これにより、高調波フィルタ５０が変圧器１７の１次側中性点に投入される。この状態では遮断器５２が投入状態で中性点電流がこちらの回路を流れてしまうため、高調波フィルタ５０に電流が流れず、ダンピング効果が得られないため高調波は減衰しない。それから、一定時間が経つと遅延回路５１が動作し、遮断器５２が開放される。これにより、中性点電流が高調波フィルタ５０を流れその抵抗分によって振動が減衰し高調波が抑制される。
【０１９４】
この第９の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、突然交流電源から切り離された状態になった場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を投入するよう、遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を常時、回路に接続しておかないので高調波フィルタ５０にかかるストレスを軽減することができる。
【０１９５】
次に、本発明の第１０の実施の形態を説明する。図２３は第１０の実施の形態に係わる遮断器回路制御装置の構成図である。この第１０の実施の形態は、中性点非接地の場合に適用されるもので、図１９に示した第８の実施の形態に対し、遅延回路５３とリセット回路５と４を追加したものである。
【０１９６】
遅延回路５３では遮断器制御回路４８から投入指令が与えられると、それから一定時間後に、それをリセット指令信号としてリセット回路５４へ与える。リセット回路５４は遮断器制御回路４８から投入指令を受け取ると、それをそのまま遮断器４９に対して指令信号として与えるが遅延回路５３からのリセット信号が「１」になると遮断器４９の投入指令を解除し開放指令とする。
【０１９７】
次に、動作を説明する。通常時の動作は第８の実施の形態と同じである。次に、自励式交直変換器３が運転中に交流系統において遮断器２１が突然三相開放となった場合の動作は、以下の通りである。遮断器２１が開放状態となることにより動揺が発生し、交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は変換器により抑制することはできないため継続する。
【０１９８】
そこで、第１０の実施の形態では、遮断器状態監視装置２４の出力が「１」となることにより、遮断器制御回路４８からリセット回路５４を介して遮断器４９に対して投入指令が与えられる。これにより、高調波フィルタ５０が変圧器１７の１次側中性点に投入される。Ｙ接続の回路の中性点に発生する電圧は零相電圧であり、高調波フィルタ５０が中性点に投入されることによって零相高調波成分は高調波フィルタ５０に吸収され、高調波フィルタ５０中の抵抗のダンピング効果により減衰し零相高調波が解消される。この状態で一定時間が経つと、遅延回路５３が動作し、リセット回路５４によって投入指令信号がリセットされ開放指令信号となり、遮断器４９は開放される。
【０１９９】
これにより、中性点回路は通常の状態に戻り、高調波フィルタ５０は切り離された状態になる。零相回路に発生する高調波は循環電流によるもので能動的なものではないので、いったん減衰すればそれが再び増幅することはない。
【０２００】
図２４に、高調波フィルタ５０を投入した後、一定時間後に再度開放した場合のシミュレーション波形を示す。高調波フィルタ５０を投入することにより交流系統母線１の母線電圧の歪みが解消し、その後に高調波フィルタ５０が開放されても歪みが再発する現象は現れていない。また、高調波フィルタ５０の投入／開放による自励式交直変換器３の運転への影響もない。
【０２０１】
第１０の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３が、突然交流電源から切り離された状態になった場合に、変圧器１７の母線側中性点回路へ一定時間のみ高調波フィルタ５０を投入するよう、遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を回路に接続しておく時間を必要最小限にするので高調波フィルタ５０にかかるストレスを軽減し、小さな定格の高調波フィルタ５０にすることができる。
【０２０２】
次に、本発明の第１１の実施の形態を説明する。図２５は第１１の実施の形態に係わる遮断器回路制御装置の構成図である。この第１１の実施の形態は、中性点直接接地の場合に適用されるもので、図２２に示した第９の実施の形態に対し、遅延回路５３、５５とリセット回路５４、５６とを追加したものである。
【０２０３】
遮断器制御回路４８の出力は、リセット回路５４を介し遮断器４９に対して投入指令として与えられる。また遅延回路５１では遮断器制御回路４８から投入指令が与えられると、それから一定時間後に、それを反転させてリセット回路５６を介して遮断器５２に開放指令を与える。遅延回路５１の出力はさらに遅延回路５５を介してリセット回路５６に対するリセット指令として与えられ、これが与えられるとリセット回路５６の出力は「開放」から「投入」へ反転する。さらに遅延回路５５の出力は遅延回路５３を介してリセット回路５４に対するリセット指令として与えられ、これが与えられるとリセット回路５４の出力は「投入」から「開放」へ反転する。
【０２０４】
次に、動作を説明する。通常時の動作は第９の実施の形態と同じである。次に、自励式交直変換器３が運転中に交流系統において遮断器２１が突然三相開放となった場合の動作を説明する。遮断器２１が開放状態となることにより動揺が発生し交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は変換器により抑制することはできないため継続する。
【０２０５】
そこで、図２５に示す第１１の実施の形態では、遮断器状態監視装置２４の出力が「１」となることにより、遮断器制御回路４８からリセット回路５４を介して遮断器４９に対し投入指令が与えられる。これにより、高調波フィルタ５０が変圧器１７の１次側中性点に投入される。この時点では高調波フィルタ５０と並列に接続されている遮断器５２が投入されている状態なので、中性点は直接接地され中性点電流（零相電流）は遮断器５２を介して大地へ流れている。この状態から一定時間が経過すると遅延回路５１が動作し、リセット回路５６を介して遮断器５２に開放指令が与えられて遮断器５２が開放され、変圧器１７の中性点は高調波フィルタ５０のみによって接地された状態になる。
【０２０６】
これにより零相高調波成分はフィルタに吸収され、フィルタ中の抵抗のダンピング効果により減衰し零相高調波が解消される。さらにこの状態で一定時間がたつと、遅延回路５５が動作し、リセット回路５６によって開放指令信号がリセットされ、遮断器５２が再投入される。また、遅延回路５３が動作し、リセット回路５４によって投入指令信号がリセットされ、遮断器４９が開放される。従って、中性点回路は通常の状態に戻り、高調波フィルタ５０は切り離された状態になる。零相回路に発生する高調波は循環電流によるもので能動的なものではないので、一旦減衰すればそれが再び増幅することはない。
【０２０７】
この第１１の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器が、突然交流電源から切り離された状態になった場合に、変圧器１７の母線側中性点回路へ一定時間のみ高調波フィルタ５０を投入するよう、遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を回路に接続しておく時間を必要最小限にするので高調波フィルタ５０にかかるストレスを軽減し、小さな定格の高調波フィルタ５０にすることができる。
【０２０８】
次に、本発明の第１２の実施の形態を説明する。図２６は第１２の実施の形態に係わる遮断器回路制御装置の構成図である。この第１２の実施の形態は、中性点非接地の場合に適用されるもので、図１９に示した第８の実施の形態に対し、系統状態監視装置として、遮断器状態監視装置２４の代わりに、交流電圧検出器５７、零相電圧検出器５８、高調波検出器５９、レベル検出器６０、積分器６１、レベル検出器６２を設けたものである。
【０２０９】
交流電圧検出器５７で検出した三相交流電圧から、零相電圧検出器５８および高調波検出器５９により零相成分の高調波電圧の大きさを検出してレベル検出器６０へ入力する。それが一定値を超えた場合、レベル検出器６０の出力が「１」となり積分器６１へ与えられる。さらに積分器６１の出力が一定レベルを超えた場合、レベル検出器６２の出力が「１」となって遮断器制御回路４８へ与えられる。その他の構成は、図１９に示す第８の実施の形態と同じである。
【０２１０】
次に、動作を説明する。通常時の動作は第８の実施の形態と同じである。次に、自励式交直変換器３が運転中に、遮断器２１の三相開放などにより突然交流電源と切り離された場合の動作を説明する。交流電源と切り離されることにより動揺が発生し交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は自励式交直変換器３により抑制することはできないため継続する。
【０２１１】
そこで、第１２の実施の形態では、三相交流電圧を、交流電圧検出器５７、零相電圧検出器５８、高調波検出器５９により処理することによって、上記のように発生した零相高調波電圧を検出し、レベル検出器６０へ与える。与えられた零相高調波電圧の大きさが一定レベルを超えていると、レベル検出器６０は「１」を出力する。それが積分回路６１で積分され、その大きさが一定レベルを超える、すなわち零相高調波が継続するとレベル検出器６２が動作して出力「１」を遮断器制御回路４８に与える。
【０２１２】
これにより、遮断器制御回路４８から遮断器４９に対して投入指令が与えられ、高調波フィルタ出力５０が変圧器１７の１次側中性点に投入される。Ｙ接続の回路の中性点に発生する電圧は零相電圧であり、高調波フィルタ５０が中性点に投入されることによって零相高調波成分は高調波フィルタ５０に吸収され、高調波フィルタ５０中の抵抗のダンピング効果により減衰し零相高調波が解消される。
【０２１３】
第１２の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３の接続された交流系統で、零相高調波電圧が増大した場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を投入するよう遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を常時、回路に接続しておかないので高調波フィルタ５０にかかるストレスを軽減することができる。
【０２１４】
次に、本発明の第１３の実施の形態を説明する。図２７は第１３の実施の形態に係わる遮断器回路制御装置の構成図である。この第１３の実施の形態は、中性点直接接地の場合に適用されるもので、図２２に示した第９の実施の形態に対し、系統状態監視装置として、遮断器状態監視装置２４の代わりに、交流電流検出器６３、高調波検出器６４、レベル検出器６０、積分器６１、レベル検出器６２を設けたものである。
【０２１５】
交流電流検出器６３、高調波検出器６４により変換器用変圧器２の１次側中性点から大地へ流れる電流の高調波成分を検出してレベル検出器６０に与え、それが一定値を超えた場合、レベル検出器６０の出力が「１」となり積分器６１へ与えられる。さらに積分器６１の出力が一定レベルを超えた場合、レベル検出器６２の出力が「１」となって遮断器制御回路４８へ与えられる。その他の構成は、図２２に示す第９の実施の形態と同じである。
【０２１６】
次に、動作を説明する。通常時の動作は第９の実施の形態と同じである。次に、自励式交直変換器３が運転中に、遮断器２１の三相開放などにより突然交流電源と切り離された場合の動作を説明する。交流電源と切り離されることにより動揺が発生し交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は自励式交直変換器３により抑制することはできないため継続する。中性点が直接接地されている場合には、中性点から大地に対して零相高調波電流が流れる。
【０２１７】
そこで、第１３の実施の形態では、変換器用変圧器２の中性点に設けた、交流電流検出器６３、高調波検出器６４により零相高調波電流を検出し、レベル検出器６０へ与える。与えられた零相高調波電流の大きさが一定レベルを超えているとレベル検出器６０は「１」を出力する。それが積分回路６１で積分され、その大きさが一定レベルを超えるとレベル検出器６２が動作して出力「１」を遮断器制御回路４８に与える。これにより、遮断器制御回路４８から遮断器４９に対して投入指令が与えられ、高調波フィルタ出力５０が変圧器１７の１次側中性点に投入される。また、遮断器制御回路４８からの信号が遅延回路５１を介して一定時間後に開放指令として遮断器５２に与えられ、遮断器５２が開放される。
【０２１８】
これにより、零相電流が高調波フィルタ５０を流れるようになり、零相高調波成分はフィルタに吸収され、フィルタ中の抵抗のダンピング効果により減衰し零相高調波が解消される。
【０２１９】
この第１３の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３の接続された交流系統で、零相高調波成分が増大した場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を挿入するよう遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波フィルタ５０を常時、回路に接続しておかないので高調波フィルタ５０にかかるストレスを軽減することができる。
【０２２０】
次に、本発明の第１４の実施の形態を説明する。図２８は第１４の実施の形態に係わる遮断器回路制御装置の構成図である。この第１４の実施の形態は、中性点非接地の場合に適用されるもので、図２３に示した第１０の実施の形態に対し、遅延回路５３の代わりに、交流電圧検出器５７、零相電圧検出器５８、高調波検出器５９、レベル検出器６５、積分器６１’、レベル検出器６２’を設けたものである。
【０２２１】
交流電圧検出器５７で検出した三相交流電圧から、零相電圧検出器５８および高調波検出器５９により零相成分の高調波電圧の大きさを検出してレベル検出器６５へ入力する。それが一定値Ｖｎ以下の場合、レベル検出器６５の出力が「１」となり積分器６１’へ与えられる。さらに積分器６１’の出力が一定レベルを超えた場合、すなわち零相高調波が小さい状態が継続した場合、レベル検出器６２’の出力が「１」となってリセット回路５４に対しリセット指令信号として与えられる。これにより、リセット回路５４が「１」すなわち投入状態の場合、それがリセットされて開放指令が遮断器４９へ与えられる。その他の構成は、図２３に示した第１０の実施の形態と同じである。
【０２２２】
次に、動作を説明する。通常時の動作は第１０の実施の形態と同じである。次に、自励式交直変換器３が運転中に、遮断器２１の三相開放などにより突然交流電源と切り離された場合の動作を説明する。交流電源と切り離されることにより動揺が発生し、交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は変換器により抑制することはできないため継続する。
【０２２３】
そこで、第１４の実施の形態では、遮断器状態監視装置２４の動作によって、遮断器制御回路４８から遮断器４９に対して投入指令が与えられ、高調波フィルタ５０が変圧器１７の１次側中性点に投入される。Ｙ接続の回路の中性点に発生する電圧は零相電圧であり、高調波フィルタ５０が中性点に投入されることによって零相高調波成分はフィルタに吸収され、高調波フィルタ５０中の抵抗のダンピング効果により減衰し零相高調波が解消される。
【０２２４】
一方、交流電圧検出器５７、零相電圧検出器５８、高調波検出器５９により交流系統母線１の母線電圧の零相高調波成分を検出しているが、上記の遮断器操作により零相高調波成分が低減されると、この検出値がレベル検出器６５の設定レベルＶｎより小さくなり、レベル検出器６５が動作する。この状態が続くと積分器６１’の出力が増加し、一定時間を超えるとレベル検出器６２’が動作してリセット回路５４にリセット指令が与えられ、これにより、遮断器４９が開放されて、高調波フィルタ５０が切り離され、中性点回路はもとの状態に戻る。零相回路に発生する高調波は循環電流によるものなので、一旦減衰すればそれが再び増幅することはなく、高調波の小さい状態が継続できる。
【０２２５】
第１４の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３の接続された交流系統で、零相高調波電圧が増大した場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を投入するよう遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波が抑制されたことを検出して高調波フィルタ５０を開放するので、高調波フィルタ５０を投入しておく時間を最小限にすることができ、高調波フィルタ５０にかかるストレスを軽減することができる。
【０２２６】
次に、本発明の第１５の実施の形態を説明する。図２９は第１５の実施の形態に係わる遮断器回路制御装置の構成図である。この第１５の実施の形態は、中性点非接地の場合に適用されるもので、図２８に示す第１４の実施の形態に対し、系統状態監視装置として、遮断器状態監視装置２４の代わりに、交流電圧検出器５７、零相電圧検出器５８、高調波検出器５９、レベル検出器６０、積分器６１、レベル検出器６２を介した信号により、遮断器制御回路４８に対し投入指令信号を与える構成としたものである。
【０２２７】
すなわち、図２６に示した第１２の実施の形態の回路と同じ回路により遮断器４９に対する投入指令を与え、図２８に示した第１４の実施の形態の回路と同じ回路により遮断器４９に対する開放指令を与える構成としたものである。
【０２２８】
次に、動作を説明する。通常時の動作は第１４の実施の形態と同じである。次に、自励式交直変換器３が運転中に、遮断器２１の三相開放などにより突然交流電源と切り離された場合の動作を説明する。電源が切り離されることにより動揺が発生し交流系統母線１に接続された回路では高調波歪みが生じる。発生した高調波のうち零相成分の高調波は自励式交直変換器３により抑制することはできないため継続する。
【０２２９】
この零相高調波の増大を検出してレベル検出器６２が動作し、遮断器回路制御装置４８およびリセット回路５４を介して遮断器４９に投入指令が与えられ、高調波フィルタ５０が変圧器１７の中性点に投入される。高調波フィルタ５０の投入により零相高調波が低減すると、今度はレベル検出器６２’が動作してリセット回路５４にリセット指令が与えられることにより、遮断器４９が開放されて、高調波フィルタ５０が切り離され、中性点回路はもとの状態に戻る。零相回路に発生する高調波は循環電流によるものなので一旦減衰すればそれが再び増幅することはなく、高調波の小さい状態が継続できる。
【０２３０】
第１５の実施の形態によれば、直流送電システムや直流電源システムに適用される自励式交直変換器３の接続された交流系統で、零相高調波成分が増大した場合に、変圧器１７の母線側中性点回路へ高調波フィルタ５０を投入するよう遮断器４９を制御することにより、自励式交直変換器３の運転に影響を与えることなく、交流系統母線１に発生した高調波歪みを高速に抑制することができる。また、高調波が抑制されたことを検出して高調波フィルタ５０を開放するので、高調波フィルタ５０を投入しておく時間を最小限にすることができ、高調波フィルタ５０にかかるストレスを軽減することができる。
【０２３１】
【発明の効果】
以上述べたように、本発明の請求項１乃至請求項４に係わる自励式交直変換器制御装置によれば、通常運転時には与えられた設定値どおりの有効電力および無効電力を出力し、自励式交直変換器が突然交流電源と切り離された場合には、交流電圧を一定に保ちつつ、接続された負荷系統や調相設備に見合った値の有効電力および無効電力を自動的に供給しながら、安定に自励式交直変換器の運転を継続することができる。
【０２３２】
さらに、接続された負荷系統や調相設備の容量が大きく、自励式交直変換器の出力が過電流になる場合には交流電圧を低減させて運転することにより、過電流を防止し自励式交直変換器の運転を継続させて負荷系統の停電を最小限にすることができる。
【０２３３】
請求項５乃至請求項６に係わる自励式交直変換器制御装置によれば、通常運転時には与えられた設定値どおりの有効電力および無効電力を出力し、自励式交直変換器が突然交流電源と切り離された場合には、交流電圧を一定に保ちつつ、接続された負荷系統や調相設備に見合った値の有効電力および無効電力を自動的に供給しながら、安定に変換器の運転を継続することができる。
【０２３４】
さらに、接続された負荷系統や調相設備の容量が大きく、自励式交直変換器の出力が過電流になる場合には、その過電流の大きさや継続時間に応じた低減幅で交流電圧を低減させて運転することにより、必要最小限の交流電圧低下で過電流を防止し変換器の運転を継続させて負荷系統の停電を最小限にすることができる。
【０２３５】
請求項７乃至請求項１０に係わる遮断器回路制御装置によれば、自励式交直変換器が接続された交流系統が交流電源と切り離されるなどの原因により、零相高調波が発生して交流電圧に大きな歪みが生じた場合に、回路の中性点に一時的に高調波フィルタを挿入するよう遮断器の操作を行うことにより、高調波を抑制して高調波による機器のストレスや変圧器の飽和などを防止し、また、常時は高調波フィルタを回路に接続しないようにすることによって、高調波フィルタのストレスを低減し、小さな容量定格の高調波フィルタとすることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図２】本発明の第１の実施の形態に係わる自励式交直変換器制御装置における過電流検出器の一例を示す構成図。
【図３】本発明の第１の実施の形態において交流電圧を低減することによる自励式交直変換器の過電流抑制の原理を説明するための主回路単線結線図。
【図４】本発明の第１の実施の形態に係わる自励式交直変換器制御装置を適用したことによる過電流抑制効果を示すシミュレーション波形図。
【図５】本発明の第２の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図６】本発明の第３の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図７】本発明の第３の実施の形態に係わる自励式交直変換器制御装置におけるＰＷＭ制御回路の内部構成を示す構成図。
【図８】本発明の第３の実施の形態に係わる自励式交直変換器制御装置でのＰＷＭ制御における正弦波信号と搬送波信号との関係を説明する波形図。
【図９】本発明の第３の実施の形態に係わる自励式交直変換器制御装置を適用したことによる過電流抑制効果を示すシミュレーション波形図。
【図１０】本発明の第４の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図１１】本発明の第５の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図１２】本発明の第６の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図１３】本発明の第６の実施の形態に係わる自励式交直変換器制御装置における過電流検出器の一例を示す構成図。
【図１４】本発明の第６の実施の形態に係わる自励式交直変換器制御装置における過電流検出器の他の一例を示す構成図。
【図１５】本発明の第６の実施の形態に係わる自励式交直変換器制御装置における過電流検出器のさらに別の他の一例を示す構成図。
【図１６】本発明の第７の実施の形態に係わる自励式交直変換器制御装置の主要部の構成図。
【図１７】本発明の第７の実施の形態に係わる自励式交直変換器制御装置におけるＰＷＭ制御回路の構成図。
【図１８】本発明の第７の実施の形態に係わる自励式交直変換器制御装置におけるＰＷＭ制御回路の中の論理演算回路の内部ロジック図。
【図１９】本発明の第８の実施の形態に係わる遮断器回路制御装置の構成図。
【図２０】本発明の第８の実施の形態における高調波フィルタの主回路結線図。
【図２１】本発明の第８の実施の形態に係わる遮断器回路制御装置を適用することによる零相高調波抑制効果を示すシミュレーション波形図。
【図２２】本発明の第９の実施の形態に係わる遮断器回路制御装置の構成図。
【図２３】本発明の第１０の実施の形態に係わる遮断器回路制御装置の構成図。
【図２４】本発明の第１０の実施の形態に係わる遮断器回路制御装置を適用することによる零相高調波抑制効果を示すシミュレーション波形図。
【図２５】本発明の第１１の実施の形態に係わる遮断器回路制御装置の構成図。
【図２６】本発明の第１２の実施の形態に係わる遮断器回路制御装置の構成図。
【図２７】本発明の第１３の実施の形態に係わる遮断器回路制御装置の構成図。
【図２８】本発明の第１４の実施の形態に係わる遮断器回路制御装置の構成図。
【図２９】本発明の第１５の実施の形態に係わる遮断器回路制御装置の構成図。
【図３０】一般的な直流送電システムに適用された従来の自励式交直変換器制御装置の構成図。
【符号の説明】
１、１Ａ 交流系統母線
２、２Ａ 変換器用変圧器
３、３Ａ 自励式交直変換器
５ 直流送電線
６ 直流電圧検出器
７ 交流電流検出器
８ 交流電圧検出器
９ 有効電力検出器
１０無効電力検出器
１１ 直流電圧／有効電力制御回路
１２ 無効電力制御回路
１３ 交流電流制御回路
１４ ｄｑ軸変換回路
１５ ＰＷＭ制御回路
１６ 位相検出回路
２４ 遮断器状態監視装置
２５、２５’ 信号保持回路
２６、２６’ １次遅れ回路
２７、２７’ 加算器
２８、２８’ スイッチ回路
２９、２９’ 電流制御要素
３０、３０’ 加算器
３１ 交流電圧検出器
３２、３２’ スイッチ回路
３３、３３’ 加算器
３４ スイッチ回路
３５ 過電流検出器
３６ 電圧制御要素
３７、３７’ 加算器
３９ 周波数偏差検出器
４１ リセット付き積分器
４８ 遮断器制御回路
４９ 遮断器
５０ 高調波フィルタ
５１ 遅延回路
５２ 遮断器
５３ 遅延回路
５４ リセット回路
５５ 遅延回路
５６ リセット回路
５７ 交流電圧検出器
５８ 零相電圧検出器
５９ 高調波検出器
６０ レベル検出器
６１、６１’ 積分器
６２、６２’ レベル検出器
６３ 交流電流検出器
６４ 高調波検出器
６５ レベル検出器
３５１ 演算回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-excited AC / DC converter controller for controlling a self-excited AC / DC converter used in a DC power transmission system or power supply system of an electric power system, and an interruption that gives an open / close command to a circuit breaker installed in the electric power system. In particular, the present invention relates to a self-excited AC / DC converter controller and a circuit breaker circuit controller for stabilizing an AC system to which a self-excited AC / DC converter is connected.
[0002]
[Prior art]
In general, when power is interchanged between power systems having different system frequencies, a DC power transmission system is used in which an AC / DC converter is installed in each AC system and the DC terminals of the AC / DC converters are mutually connected. An AC / DC converter is also used when power is supplied from a DC power source such as a battery to an AC system. As an AC / DC converter used in such a power system, a separately-excited converter has been conventionally used. However, in recent years, a self-excited AC / DC converter has been applied.
[0003]
FIG. 30 shows a DC power transmission system using voltage-type self-excited AC / DC converters 3 and 3A and its self-excited AC / DC converter controller 47. A self-excited AC / DC converter 3 is connected via a converter transformer 2 to an AC system bus 1 connected to an AC system including an AC power source such as a generator behind. The self-excited AC / DC converter 3 includes a 6-phase or 12-phase bridge circuit including a GTO (gate turn-off) thyristor and a diode connected in antiparallel. A capacitor 4 is connected to the DC terminal side of the self-excited AC / DC converter 3, and a self-excited AC / DC converter 3 </ b> A and a capacitor 4 </ b> A having the same configuration as the self-excited AC / DC converter 3 are connected to the capacitor 4 via a DC transmission line 5. ing. The AC terminal side of the self-excited AC / DC converter 3A is connected to an AC system bus 1A of another AC system via a transformer 2A.
[0004]
One of the self-excited AC / DC converters 3 and 3A is operated as a forward converter (converting AC power into DC power), and the other is operated as an inverse converter (converting DC power into AC power) to accommodate power. Is done. In the following description, a case where the self-excited AC / DC converter 3 is used as a forward converter will be described. In addition, as the self-excited AC / DC converter control device 47 and the detectors 6, 7, 8 and the like, both self-excited AC / DC converters 3 and 3A have the same configuration. Only 3 is shown.
[0005]
On the self-excited AC / DC converter 3 side, the DC voltage Ed is detected by the DC voltage detector 6, the three-phase AC current Ia of the converter output detected by the AC current detector 7 and the AC voltage detector 8. The active power detector 9 detects the active power output Pa of the self-excited AC / DC converter 3 and the reactive power detector 10 detects the reactive power output Qa based on the AC system bus voltage Va.
[0006]
The DC voltage Ed is matched with the DC voltage set value Edref, and the deviation (Edref−Ed) is input to the first input terminal of the DC voltage / active power control circuit 11. The active power Pa is matched with the active power set value Pref, and the deviation (Pref−Pa) is input to the second input terminal of the DC voltage / active power control circuit 11.
[0007]
On the other hand, the reactive power Qa is matched with the reactive power set value Qref, and the deviation (Qref−Qa) is input to the reactive power control circuit 12. The DC voltage / active power control circuit 11 and the reactive power control circuit 12 output a control signal for making each input deviation signal zero. The output signals are input to the alternating current control circuit 13 as the active power component set value Idref and reactive power component set value Iqref of the converter output current, respectively. Further, the alternating current Ia is separated into two orthogonal (d-axis and q-axis) components, that is, an active power component Id and a reactive power component Iq, by the dq axis conversion circuit 14, and the detected values are supplied to the AC current control circuit 13. Given.
[0008]
The AC current control circuit 13 calculates and outputs control rates Cmd and Cmq such that the active power component Id and the reactive power component Iq of the AC current Ia follow the set value Idref and the set value Iqref, respectively. Here, the control rates Cmd and Cmq are values obtained by separating the sine wave signal used in the PWM control circuit 15 into two orthogonal axis components, and the magnitude of the vector sum, that is, the control rate Cm (the square of Cmd). And the square root of the square of the control rate Cmq) corresponds to the peak value of the sine wave. The angle of the vector sum, ie tan ^-1 (Cmq / Cmd) corresponds to the relative phase angle of the PWM sine wave signal with respect to the voltage phase of the AC system bus 1. Furthermore, since this PWM sine wave signal is in a substantially proportional relationship with the fundamental wave component of the AC output voltage of the self-excited AC / DC converter 3, the control rates Cmd and Cmq are converted into two-axis components orthogonal to the converter output voltage. It can be said that it is equivalent to a disassembled one.
[0009]
On the other hand, the phase detection circuit 16 detects the phase θv of the AC voltage from the three-phase AC voltage signal Va of the AC system bus 1 obtained from the AC voltage detector 8 and supplies it to the dq axis conversion circuit 14 and the PWM control circuit 15. The dq axis conversion circuit 14 performs three-phase / two-phase conversion and dq axis conversion of the converter output current using the given phase θv as a reference phase, and the PWM control circuit 15 obtains the control rates Cmd, Cmq and the reference phase θv. The generated sine wave signal and carrier wave signal are matched, and the generation timing of the switching signal applied to the GTO thyristor constituting the self-excited AC / DC converter 3 is determined. The self-excited AC / DC converter 3 performs a desired operation by switching the GTO thyristor of the bridge circuit according to the pulse signal thus obtained.
[0010]
By using such self-excited AC / DC control devices 3 and 3A, in the DC power transmission system, while maintaining the DC voltage as the set value Edref, the power according to the active power set value Pref is inversely converted from the forward converter side. It is possible to output reactive power according to the reactive power set value Qref at each converter.
[0011]
Here, in the case of the power supply system, a DC power supply such as a battery is connected to the other end of the DC circuit instead of the self-excited AC / DC converter 3A on the other side, and only the DC voltage control is not necessary, The configuration is the same as that of the DC power transmission system shown in FIG.
[0012]
[Problems to be solved by the invention]
However, when the conventional self-excited AC / DC converter controller 47 as shown in FIG. 30 is used, in the AC system behind the AC system bus 1 to which the self-excited AC / DC converter 3 is connected, the AC system bus 1 When the generator is disconnected due to, for example, opening the circuit breaker connected to, AC overvoltage or AC voltage drop may occur, resulting in equipment breakage or load system power outage. This is because the self-excited AC / DC converter 3 operates so as to continue to supply active power and reactive power according to the set values Pref and Qref, but these values are not necessarily limited to the capacity of the connected load system or phase adjusting equipment. This is because the balance is not achieved.
[0013]
In such a case, in order to perform the operation balanced with the load system and the phase adjusting equipment, for example, publicly known literature (1997 Institute of Electrical Engineers of Japan / Electric Power and Energy Division Conference No. 320 “Self-excited AC / DC converter for DC interconnection”) As shown in (1))), the self-excited AC / DC converter 3 detects that the AC system bus is disconnected from the power source (generator), and detects AC voltage control. A method of performing alternating current control using the current value itself as a set value is proposed.
[0014]
If this method is used, an operating point balanced with the load system and the phase adjusting equipment can be obtained. However, if the capacity of the load system and the phase adjusting equipment is larger than the converter capacity, the overload system continuously There is a problem that the self-excited AC / DC converter 3 is stopped due to an electric current, the power supply is not performed, and the load system completely fails.
[0015]
Further, when the harmonic distortion of the zero phase component occurs in the voltage waveform of the AC system bus 1 to which the self-excited AC / DC converter 3 is connected due to the fluctuation immediately after being disconnected from the generator, the control of the self-excited AC / DC converter 3 is performed. Can not suppress harmonics, and distortion continues for a long time, resulting in increased stress on the connected equipment, or causing saturation of the transformer 2 and generating new harmonics. is there.
[0016]
That is, the transformer 2 that connects the self-excited AC / DC converter 3 and the AC system bus 1 generally has a secondary side (converter 3 side) winding Δ connected, and even in the case of Y connection, the neutral point is Ungrounded. Therefore, the zero-phase circuit on the primary side (AC system bus 1 side) and the secondary side (converter 3 side) are disconnected from each other, and the harmonics generated in the zero-phase circuit on the AC system bus 1 side are converted to the converter 3. Cannot be suppressed.
[0017]
It is an object of the present invention to continue operation even when a self-excited AC / DC converter applied to a DC power transmission system or a power supply system is suddenly disconnected from an AC power source such as a generator, and is suitable for a connected load system. It is an object of the present invention to provide a self-excited AC / DC converter control device capable of continuously supplying electric power.
[0018]
Another object of the present invention is to provide a circuit breaker circuit control device capable of suppressing harmonic distortion generated in a zero-phase circuit of an AC system disconnected from a power source.
[0019]
[Means for Solving the Problems]
The self-excited AC / DC converter control device according to the invention of claim 1 is: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter, A dq axis conversion circuit for converting an AC output current of the self-excited AC / DC converter into a two-axis variable of an active power component d-axis and a reactive power component q-axis on an orthogonal coordinate axis; and a DC voltage of the DC power transmission system A DC voltage / active power control circuit that calculates the d-axis setting value that satisfies a predetermined active power setting value while maintaining the setting value, and a q-axis setting value that satisfies the predetermined reactive power setting value A reactive power control circuit to calculate; an AC current control circuit to calculate a control rate such that each of the d-axis and q-axis output currents from the dq-axis conversion circuit follows the set values of the d-axis and q-axis; A phase detection circuit that detects the AC voltage phase of the bus of the AC power system, and a DC voltage that is set based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit while maintaining the set value. Value The PWM control circuit that controls the self-excited AC / DC converter so as to output the active power and reactive power of the AC system and the generator of the AC system to which the self-excited AC / DC converter is connected are disconnected. A system state monitoring device that performs the operation of the system state monitoring device, a signal holding circuit that holds the output of the alternating current control circuit at a value of a previous operation state and outputs the value to the PWM control circuit, and the dq axis conversion circuit A first-order lag circuit that inputs the d-axis and q-axis output currents and outputs first-order lag d-axis and q-axis output currents, and the d-axis and q-axis output currents by the operation of the system state monitoring device. A current control element that calculates the control rate correction signal based on a deviation from the first-order lag d-axis and q-axis output currents and outputs it to the PWM control circuit, and the AC voltage of the AC system is its voltage setting value. A voltage control element that outputs a correction signal for correcting the control rate to the PWM control circuit so that the absolute value increases when the absolute value decreases when the absolute value decreases. And an overcurrent detector that reduces the voltage setting value of the voltage control element to a small value when the AC output current of the AC / DC converter continuously exceeds a predetermined value for a predetermined time or longer.
[0020]
In the self-excited AC / DC converter control device according to the first aspect of the present invention, when the AC circuit breaker to which the self-excited AC / DC converter is connected is opened, or the frequency of the AC system to which the self-excited AC / DC converter is connected. Of the sine wave signal used in pulse width control so that the voltage of the AC bus connected to the self-excited AC / DC converter becomes equal to the set value when the value deviates from a certain value range for a certain period of time. The control is switched to adjust the peak value, and the value through the first-order lag circuit is set for each value of the AC output current of the self-excited AC / DC converter converted into a biaxial variable on the Cartesian coordinate axis Then, the output current is controlled so as to follow the value, and the control is switched so as to correct the value of the sine wave signal by the output. Furthermore, when the AC current detection value of the self-excited AC / DC converter deviates from a certain range for a certain time or longer in this state, the setting value of the AC voltage is switched to a smaller value.
[0021]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, AC overvoltage and voltage drop are prevented, and active power and reactive power with values appropriate for the connected load system and phase-adjusting equipment are supplied. However, the operation of the self-excited AC / DC converter can be continued stably, and if the capacity of the load system and phase adjusting equipment is larger than the converter capacity, the AC voltage can be operated at a lower value. Overcurrent of the converter can be prevented and the self-excited AC / DC converter can be continuously operated.
[0022]
The self-excited AC / DC converter control device according to the invention of claim 2 is: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter, A dq axis conversion circuit for converting an AC output current of the self-excited AC / DC converter into a two-axis variable of an active power component d-axis and a reactive power component q-axis on an orthogonal coordinate axis; and a DC voltage of the DC power transmission system A DC voltage / active power control circuit that calculates the d-axis setting value that satisfies a predetermined active power setting value while maintaining the setting value, and a q-axis setting value that satisfies the predetermined reactive power setting value A reactive power control circuit to calculate; an alternating current control circuit to calculate a control rate such that each of the d-axis and q-axis output currents from the dq-axis conversion circuit follows the setting of the d-axis and q-axis; A phase detection circuit for detecting the AC voltage phase of the AC power system, and the set value while maintaining the DC voltage at the set value based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit. Effectiveness A PWM control circuit for controlling said self-commutated AC-DC converter to output the force and reactive power,
A system state monitoring device that operates when the generator of the AC system to which the self-excited AC / DC converter is connected is disconnected, and the output of the AC current control circuit is preliminarily determined by the operation of the system state monitoring device. A signal holding circuit that holds the value of the operating state and outputs it to the PWM control circuit, and the d-axis and q-axis output currents from the dq-axis conversion circuit are input, and the d-axis and q-axis output currents of the first order lag are input. The control ratio correction signal is calculated based on the deviation between the output currents of the primary delay circuit to output and the output currents of the d-axis and q-axis and the output currents of the primary delay d-axis and q-axis by the operation of the system state monitoring device. The current control element to be output to the PWM control circuit and the AC voltage of the AC system bus so that the absolute value is increased when the absolute value is decreased so that the absolute value is decreased when the voltage is higher than the voltage setting value. in front A voltage control element that outputs a correction signal for correcting the control rate to the PWM control circuit, and the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for a predetermined time or longer in the PWM control circuit. For the peak value of a sine wave signal used in pulse width control Limit value And an overcurrent detector that makes the value smaller than usual.
[0023]
In the self-excited AC / DC converter control device according to the invention of claim 2, when the AC system breaker to which the self-excited AC / DC converter is connected is opened, or the frequency of the AC system to which the self-excited AC / DC converter is connected Of the sine wave signal used in the pulse width control so that the voltage of the AC system bus connected to the self-excited AC / DC converter becomes equal to the set value when it deviates from a certain value range for a certain period of time. The control is switched to adjust the peak value, and the value through the first-order lag circuit is set for each value of the AC output current of the self-excited AC / DC converter converted into a biaxial variable on the Cartesian coordinate axis Then, the output current is controlled so as to follow the value, and the control is switched so as to correct the value of the sine wave signal by the output. Furthermore, if the AC current detection value of the self-excited AC / DC converter continues beyond a certain range for a certain time in that state, the limit value for the peak value of the sine wave signal used in the pulse width control is smaller than usual. Switch to value.
[0024]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, the AC overvoltage and voltage drop are prevented, and the active power and the invalid value are in accordance with the connected load system and phase-adjusting equipment. The operation of the self-excited AC / DC converter can be continued stably while supplying power, and if the capacity of the load system and phase adjusting equipment is larger than the capacity of the self-excited AC / DC converter, the AC voltage must be lowered. By operating with the value, the overcurrent of the self-excited AC / DC converter can be prevented, and the self-excited AC / DC converter can be continuously operated.
[0025]
The self-excited AC / DC converter control device according to the invention of claim 3 is: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter, A dq axis conversion circuit for converting an AC output current of the self-excited AC / DC converter into a two-axis variable of an active power component d-axis and a reactive power component q-axis on an orthogonal coordinate axis; and a DC voltage of the DC power transmission system A DC voltage / active power control circuit that calculates the d-axis setting value that satisfies a predetermined active power setting value while maintaining the setting value, and a q-axis setting value that satisfies the predetermined reactive power setting value A reactive power control circuit to calculate; an AC current control circuit to calculate a control rate such that each of the d-axis and q-axis output currents from the dq-axis conversion circuit follows the set values of the d-axis and q-axis; A phase detection circuit for detecting an AC voltage phase of an AC system bus of the power supply system, and a DC voltage is maintained at a set value based on an AC voltage phase from the phase detection circuit and a control rate from the AC current control circuit. Na The PWM control circuit for controlling the self-excited AC / DC converter so as to output active power and reactive power according to the set value, and the AC generator to which the self-excited AC / DC converter is connected are disconnected. A system state monitoring device that operates when the system state monitoring device operates, a signal holding circuit that maintains the output of the AC current control circuit at a value of a previous operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit, and the dq A first-order lag circuit that inputs the d-axis and q-axis output currents from the axis conversion circuit and outputs first-order lag d-axis and q-axis output currents; A current control element that calculates a correction signal of the control rate based on a deviation between each output current and a first-order lag d-axis and q-axis output current and outputs the correction signal to the PWM control circuit;
When the AC voltage of the AC system bus rises above its voltage setting value, the PWM signal is used to correct the control rate so that the absolute value increases when the absolute value decreases. When the AC output current of the voltage control element to be output to the circuit and the self-excited AC / DC converter exceeds a predetermined value for a predetermined time or longer, the voltage control value of the voltage control element is decreased and the PWM control is performed. For the peak value of a sine wave signal used in pulse width control in a circuit Limit value And an overcurrent detector that makes the value smaller than usual.
[0026]
In the self-excited AC / DC converter control device according to the invention of claim 3, when the AC circuit breaker to which the self-excited AC / DC converter is connected is opened, or the frequency of the AC system to which the self-excited AC / DC converter is connected Of the sine wave signal used in the pulse width control so that the voltage of the AC bus connected to the self-excited AC / DC converter becomes equal to the set value when it deviates from a certain value range for a certain period of time. The control is switched to adjust the peak value, and the value through the first-order lag circuit is set for each value of the AC output current of the self-excited AC / DC converter converted into a biaxial variable on the Cartesian coordinate axis Then, the output current is controlled so as to follow the value, and the control is switched so as to correct the value of the sine wave signal by the output. Furthermore, when the AC current detection value of the self-excited AC / DC converter deviates from a certain range for a certain period of time in that state, the setting value of the AC voltage is switched to a smaller value and the sine used for pulse width control. The limit value for the peak value of the wave signal is switched to a smaller value than usual.
[0027]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, AC overvoltage and voltage drop are prevented, and active power and reactive power with values appropriate for the connected load system and phase-adjusting equipment are supplied. However, if the self-excited AC / DC converter can be operated stably and the capacity of the load system and phase adjusting equipment is larger than the capacity of the self-excited AC / DC converter, the AC voltage can be operated at a lower value. By doing so, an overcurrent of the self-excited AC / DC converter can be prevented, and the self-excited AC / DC converter can be continuously operated.
[0028]
The self-excited AC / DC converter control device according to the invention of claim 4 is: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter, A dq axis conversion circuit for converting an AC output current of the self-excited AC / DC converter into a two-axis variable of an active power component d-axis and a reactive power component q-axis on an orthogonal coordinate axis; and a DC voltage of the DC power transmission system A DC voltage / active power control circuit that calculates the d-axis setting value that satisfies a predetermined active power setting value while maintaining the setting value, and a q-axis setting value that satisfies the predetermined reactive power setting value A reactive power control circuit to calculate; an AC current control circuit to calculate a control rate such that each of the d-axis and q-axis output currents from the dq-axis conversion circuit follows the set values of the d-axis and q-axis; A phase detection circuit for detecting an AC voltage phase of an AC system bus of the power supply system, and a DC voltage is maintained at a set value based on an AC voltage phase from the phase detection circuit and a control rate from the AC current control circuit. Na The PWM control circuit for controlling the self-excited AC / DC converter so as to output active power and reactive power according to the set value, and the AC generator to which the self-excited AC / DC converter is connected are disconnected. A system state monitoring device that operates when the system state monitoring device operates, a signal holding circuit that maintains the output of the AC current control circuit at a value of a previous operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit, and the dq A first-order lag circuit that inputs the d-axis and q-axis output currents from the axis conversion circuit and outputs first-order lag d-axis and q-axis output currents; A current control element that calculates a correction signal of the control rate based on a deviation between each output current and a first-order lag d-axis and q-axis output current and outputs the correction signal to the PWM control circuit;
When the AC voltage of the AC system bus rises above its voltage setting value, the PWM signal is used to correct the control rate so that the absolute value increases when the absolute value decreases. When the AC output current of the voltage control element to be output to the circuit and the self-excited AC / DC converter continuously exceeds a predetermined value for a certain period of time and the reactive power component advances and is reactive power, the voltage setting value of the AC voltage is reduced. When the value is switching delay reactive power, the peak value of the sine wave signal used in the pulse width control in the PWM control circuit Limit value And an overcurrent detector that makes the value smaller than usual.
[0029]
In the self-excited AC / DC converter control device according to the invention of claim 4, when the AC circuit breaker to which the self-excited AC / DC converter is connected is opened, or the frequency of the AC system to which the self-excited AC / DC converter is connected Of the sine wave signal used in the pulse width control so that the voltage of the AC system bus connected to the self-excited AC / DC converter becomes equal to the set value when it deviates from a certain value range for a certain period of time. The control is switched to adjust the peak value, and the value through the first-order lag circuit is set for each value of the AC output current of the self-excited AC / DC converter converted into a biaxial variable on the Cartesian coordinate axis Then, the output current is controlled so as to follow the value, and the control is switched so as to correct the value of the sine wave signal by the output. Furthermore, when the AC current detection value of the self-excited AC / DC converter has deviated from the range that has continued for a certain period of time in that state, the AC power depends on whether the reactive power component of the AC output current is delayed reactive power or advanced reactive power. Select whether to switch the voltage setting value to a smaller value or to switch the limit value for the peak value of the sine wave signal used in pulse width control to a smaller value than normal, and switch accordingly. .
[0030]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, the AC overvoltage and voltage drop are prevented, and the active power and the invalid value are in accordance with the connected load system and phase-adjusting equipment. If the operation of the self-excited AC / DC converter can be continued stably while supplying electric power, and the capacity of the load system and phase adjusting equipment is larger than the capacity of the self-excited AC / DC converter, the AC voltage is lowered. By operating at this value, overcurrent of the self-excited AC / DC converter can be prevented, and the operation of the self-excited AC / DC converter can be continued.
[0031]
The self-excited AC / DC converter control device according to the invention of claim 5 is the self-excited AC / DC converter control device according to claim 1, 3 or 4, wherein the overcurrent detector is the self-excited AC / DC converter. When the AC output current exceeds a predetermined value for a certain period of time and the voltage setting value of the AC voltage is set to a small value, the reduction range of the voltage setting value is a value corresponding to the magnitude and duration of the AC output current. It is characterized by that.
[0032]
In the self-excited AC / DC converter control device according to the invention of claim 5, in addition to the operation of the overcurrent detector of the self-excited AC / DC converter control device according to claim 1, claim 3 or claim 4, the self-excited AC / DC converter is provided. When the AC output current of the converter deviates beyond a certain range and becomes overcurrent, the range of reduction in the set value of the AC voltage to be switched depends on the magnitude and duration of the overcurrent. Value.
[0033]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, the AC overvoltage and voltage drop are prevented, and the active power and the invalid value are in accordance with the connected load system and phase-adjusting equipment. When the operation of the self-excited AC / DC converter can be continued stably while supplying electric power, and the capacity of the load system and phase adjusting equipment is larger than the capacity of the self-excited AC / DC converter, the AC voltage is supplied to the load system. In addition, by operating at a lower value according to the capacity of the phase adjusting equipment, the overcurrent of the self-excited AC / DC converter can be prevented, and the self-excited AC / DC converter can be continuously operated.
[0034]
The self-excited AC / DC converter control device according to claim 6 is the self-excited AC / DC converter control device according to claim 2, or 3 or 4, wherein the overcurrent detector is the self-excited AC / DC converter. The AC output current of the converter continuously exceeds a predetermined value for a certain time, and the peak value of the sine wave signal used in the pulse width control in the PWM control circuit Limit value When the value is set to a smaller value than usual, the reduction range of the limit value with respect to the peak value of the sine wave signal is set to a value corresponding to the magnitude and duration of the overcurrent of the AC output current. To do.
[0035]
In the self-excited AC / DC converter control device according to the invention of claim 6, in addition to the operation of the overcurrent detector of the self-excited AC / DC converter control device according to claim 2, claim 3 or claim 4, the self-excited AC / DC converter is provided. When the AC output current of the converter becomes an overcurrent, the reduction width of the limit value for the peak value of the sine wave signal of the pulse width control for switching is set to a value according to the magnitude and duration of the overcurrent. To do.
[0036]
As a result, even when the self-excited AC / DC converter is suddenly disconnected from the generator, the AC overvoltage and voltage drop are prevented, and the active power and the invalid value are in accordance with the connected load system and phase-adjusting equipment. When the operation of the self-excited AC / DC converter can be continued stably while supplying electric power, and the capacity of the load system and phase adjusting equipment is larger than the capacity of the self-excited AC / DC converter, the AC voltage is supplied to the load system. In addition, by operating at a lower value according to the capacity of the phase adjusting equipment, the overcurrent of the self-excited AC / DC converter can be prevented, and the self-excited AC / DC converter can be continuously operated.
[0037]
The circuit breaker circuit control device according to the invention of claim 7 is connected to the same AC system bus to which the self-excited AC / DC converter according to any one of claims 1 to 6 is connected, or a nearby AC system bus. A circuit breaker and a harmonic filter are installed in series between the neutral point of the connected transformer and the ground. Normally, the circuit breaker is opened and the AC system is connected to the self-excited AC / DC converter. It has a circuit breaker control circuit for turning on the circuit breaker when the generator is disconnected, and the harmonic filter is suppressed by the harmonic filter.
[0038]
In the circuit breaker circuit control device according to the invention of claim 7, it is installed between the neutral point of the transformer connected to the same AC system bus or the nearby AC system bus to which the self-excited AC / DC converter is connected and the ground. The circuit breaker for turning on / off the harmonic filter to be controlled is controlled. Normally, the circuit breaker is opened and the self-excited AC / DC converter is disconnected from the AC power supply, or the frequency of the AC system to which the self-excited AC / DC converter is connected deviates from a certain range for a certain period of time. On the condition, the circuit breaker is given a command to insert the harmonic filter between the neutral point of the transformer and the ground.
[0039]
This suppresses harmonic distortion by absorbing the harmonic current of the zero-phase circuit generated when the self-excited AC / DC converter is disconnected from the power supply system by the harmonic filter inserted at the neutral point of the transformer. can do.
[0040]
The circuit breaker circuit control device according to the invention of claim 8 is the circuit breaker circuit control device according to claim 7, wherein a predetermined time elapses after the circuit breaker control circuit gives a closing command to the circuit breaker. Is characterized by issuing a command to open the circuit breaker.
[0041]
In the circuit breaker circuit control device according to the invention of claim 8, in addition to the action of the circuit breaker circuit control device according to claim 7, the circuit breaker is normally opened and the self-excited AC / DC converter is disconnected from the AC power source. The harmonic filter is connected between the neutral point of the transformer and the ground on the condition that the frequency of the AC system to which the self-excited AC / DC converter is connected deviates from a certain range for a certain period of time. An insertion command is given to the circuit breaker so as to be inserted between them, and after a certain time has elapsed, an opening command is given to the circuit breaker so as to disconnect the harmonic filter from the circuit again.
[0042]
As a result, the harmonic current of the zero-phase circuit generated when the self-excited AC / DC converter is suddenly disconnected from the power supply system is absorbed by the harmonic filter inserted at the neutral point of the transformer to reduce the harmonic distortion. In addition, the stress and loss applied to the inserted harmonic filter can be minimized.
[0043]
The circuit breaker circuit control device according to the invention of claim 9 is connected to the same AC system bus to which the self-excited AC / DC converter according to any one of claims 1 to 6 is connected, or a nearby AC system bus. An AC system bus with a circuit breaker and a harmonic filter installed in series between the neutral point of the connected transformer and the earth, with the circuit breaker open during normal operation and a self-excited AC / DC converter connected The circuit has a circuit breaker control circuit for turning on the circuit breaker when the harmonic component of the zero-phase voltage exceeds a certain value, and the harmonics are suppressed by the harmonic filter.
[0044]
In the circuit breaker circuit control device according to the invention of claim 9, it is installed between the neutral point of the transformer connected to the same AC system bus to which the self-excited AC / DC converter is connected or a nearby AC system bus and the ground. The harmonic component of the zero-phase voltage of the AC system bus voltage with the circuit breaker open and the self-excited AC / DC converter connected to it. Is given a command to the circuit breaker so that the harmonic filter is inserted between the neutral point of the transformer and the ground on the condition that the current exceeds a certain value.
[0045]
As a result, the harmonic current of the zero-phase circuit can be absorbed by the harmonic filter inserted at the neutral point of the transformer to suppress the harmonic distortion.
[0046]
The circuit breaker circuit control device according to the invention of claim 10 is the circuit breaker circuit control device according to claim 7 or claim 9, wherein the AC system bus of the self-excited AC / DC converter is in a state where the circuit breaker is turned on. The circuit breaker is opened when the magnitude of the harmonics of the zero-phase voltage is not less than a predetermined value for a certain period of time.
[0047]
In the circuit breaker circuit control device according to the invention of claim 10, in addition to the action of the circuit breaker circuit control device according to claim 7 or 9, a harmonic filter is disposed between the neutral point of the transformer and the ground. With the circuit breaker to be connected turned on, the harmonic component of the zero phase voltage of the AC system bus to which the self-excited AC / DC converter is connected has been within a certain range of values for a certain period of time. An open command is given to the circuit breaker to disconnect the wave filter from the circuit.
[0048]
As a result, the harmonic current of the zero-phase circuit can be absorbed by the harmonic filter inserted at the neutral point of the transformer to suppress harmonic distortion, and the stress and loss on the harmonic filter can be minimized. To the limit.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of the main part of the self-excited AC / DC converter control device 47 according to the first embodiment of the present invention. The same components as those in the conventional example shown in FIG. While the description is omitted, the same components of the main circuit portion and the signal detection portion that are the same as the conventional method are not shown.
[0050]
In FIG. 1, an alternating current control circuit 13 and a dq axis conversion circuit 14 are the same as those in the conventional example shown in FIG. 30, and the signals given to the respective circuits are also the same. The PWM control circuit 15 outputs a pulse signal to the self-excited AC / DC converter 3 as in the conventional example. In the conventional example, the control rate signals Cmd and Cmq are directly received from the AC current control circuit 13. On the other hand, in the first embodiment, a signal obtained by correcting the output of the alternating current control circuit 13 is input. Further, the AC system bus 1 is the same as the AC system bus 1 of the conventional example shown in FIG. 30, and a load system 18 and a generator 22 are additionally shown.
[0051]
A load system 18 and phase adjusting equipment 19 are connected to the AC system bus 1 via a transformer 17 in parallel with the self-excited AC / DC converter 3. A power supply system 23 including a plurality of generators 22 is connected via the AC power transmission line 20 and the circuit breakers 21 and 21 '. The circuit breaker state monitoring device 24 as a system state monitoring device monitors the state of whether the circuit breakers 21 and 21 ′ at both ends of the power transmission line 20 are in the on state or the open state. When 21 ′ is in a three-phase open state, a control switching command signal is output to the self-excited AC / DC converter controller 47.
[0052]
In the self-excited AC / DC converter control device 47, the control rates Cmd and Cmq, which are the outputs of the alternating current control circuit 13, are given to the signal holding circuits 25 and 25 ′, respectively, and further holding commands are sent to the signal holding circuits 25 and 25 ′. As a signal, a control switching command signal which is an output of the circuit breaker state monitoring device 24 is given. The biaxial components Id and Iq of the converter AC output current, which is the output of the dq axis conversion circuit 14, are given to the primary delay circuits 26 and 26 ′, and the outputs of the primary delay circuits are transmitted via the primary delay. Differences are calculated by the adders 27 and 27 ′ and the Id and Iq signals that are not present, and are input to the switch circuits 28 and 28 ′. The switch circuits 28 and 28 'are in an open state during normal operation, and the output of the circuit breaker state monitoring device 24 is given as a switch-on command signal. The outputs of the switch circuits 28 and 28 'are supplied to current control elements 29 and 29' comprising a proportional integration circuit, and the outputs are added to the outputs of the signal holding circuits 25 and 25 'by adders 30 and 30'.
[0053]
On the other hand, the AC voltage detector 31 detects the voltage magnitude Vac of the AC system bus 1. The adders 33 and 33 ′ match the voltage set value Vref with the deviation of the output of the switch circuit 32 and the detected voltage Vac, and the resulting value is input to the switch circuit 34.
[0054]
Here, a value close to 100% of the rated voltage is given as the voltage setting value Vref, and a value such as 30% of the rating, for example, is set as the reduction width ΔVref of the AC voltage setting value at the input terminal of the switch circuit 32. Is given. The switch circuit 32 is normally open and is turned on when an overcurrent of the converter output current is detected by the overcurrent detector 35.
[0055]
FIG. 2 is an internal configuration diagram of the overcurrent detector 35. The overcurrent detector 35 receives the Id and Iq values obtained by converting the detected value of the converter output current into two orthogonal axes and the output of the circuit breaker state monitoring device 24. The values of Id and Iq are given to the arithmetic circuit 351, and the magnitude of the current I is obtained by performing the calculation of the following equation (1).
[0056]
[Expression 1]

[0057]
The result is given to the level detector 352, and “1” is output when it exceeds a certain level, for example, 80% of the converter rated current, and is input to the AND circuit 353. On the other hand, the signal given from the circuit breaker state monitoring device 24 is also inputted to the AND circuit 353, and when both signals become “1”, the output of the AND circuit 353 becomes “1” and is given to the integrator 354.
[0058]
Here, the circuit breaker state monitoring device 24 outputs “1” when the AC circuit breakers 21 and 21 ′ are three-phase open. The integrator 354 integrates the output of the AND circuit 353, and the output is given to the level detector 355. When the output exceeds a certain value, a closing command signal is given to the switch circuit 32.
[0059]
On the other hand, in FIG. 1, the switch circuit 34 is also normally open, and when the output of the breaker state monitoring device 24 is given as a closing command signal, the switch circuit 34 is closed and the output is given to the voltage control element 36. It is done. The voltage control element 36 is constituted by a proportional integration circuit, and its output is given to the adders 37 and 37 ′ and further added to the outputs of the adders 30 and 30 ′. The values obtained as a result are input to the PWM control circuit 15 as corrected control rates Cmd ′ and Cmq ′. The PWM control circuit 15 generates a pulse signal for the self-excited AC / DC converter 3 based on those values and the voltage phase θv of the AC system bus 1 obtained from the phase detector 16.
[0060]
Next, the operation of the self-excited AC / DC converter controller 47 will be described. First, since the AC circuit breakers 21 and 21 'are normally turned on, the self-excited AC / DC converter 3 is connected to a plurality of generators 22, and is given from, for example, a central power supply command station. The active power command value Pref and the reactive power command value Qref are operated while supplying or absorbing the active power and the reactive power to the AC system bus 1. Since active power and reactive power are supplied from both the plurality of generators 22 and the self-excited AC / DC converter 3 to the load system 18 and the phase adjusting equipment 19 in the vicinity of the self-excited AC / DC converter, the self-excited AC / DC conversion is performed. Even if the outputs of the active power and reactive power of the device 3 do not necessarily match the capacities of the load system 18 and the phase adjusting equipment 19, the AC voltage is kept near the rated value and stable operation is possible.
[0061]
On the other hand, since the circuit breakers 21 and 21 'are in the on state, the output of the circuit breaker state monitoring device 24 is off, and the switch circuits 28, 28' and 34 that are turned on by this signal are all open. Further, the signal holding circuits 25 and 25 ′ that hold the input value at a previous value by the output signal of the circuit breaker state monitoring device 24 are not operating, and the control rates Cmd and Cmq given from the AC current control circuit 13 are not changed. It is output. As a result, the outputs of the current control elements 29, 29 'and the voltage control element 36 given to the adders 30, 30', 37, 37 'are all zero, and the outputs of the signal holding circuits 26, 26' are input respectively. Equal to value. Such an operating state is exactly the same as when the conventional self-excited AC / DC converter control device shown in FIG. 30 is used.
[0062]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are compared with the capacity of the self-excited AC / DC converter 3. The operation when it is small will be described.
[0063]
When the circuit breaker 21 is opened in three phases, the AC system bus 1 and the self-excited AC / DC converter 3, the load system 18, and the phase adjusting equipment 19 connected thereto are completely disconnected from the power system 23 including the generator 22. It will be in the state. Therefore, it is necessary to supply appropriate active power and reactive power from the self-excited AC / DC converter 3 to the load system 18 and the phase adjusting equipment 19, but the active power set value Pref, which is used during normal operation, Although the reactive power set value Qref is not a value commensurate with the size of the connected load system 18 or the phase adjusting equipment 19, the self-excited AC / DC converter 3 maintains the set values even after the circuit breaker 21 is opened. As the active power and reactive power are continuously supplied or absorbed, an AC overvoltage or a voltage drop may occur, and stable operation may not be possible.
[0064]
Therefore, in the self-excited AC / DC converter control device 47 according to the first embodiment, the circuit breaker state monitoring device 24 detects that the circuit breaker 21 has become three-phase open, and the switch circuits 28, 28 ′, 34. . The signal holding circuits 25 and 25 ′ hold the respective output values at the values when the holding command is given.
[0065]
On the other hand, in the overcurrent detector 35, since the capacity of the load system 18 and the phase adjusting equipment 19 to be connected is small, the level detector 352 does not operate, and the outputs of the integrator 353 and the level detector 354 are “0”. The input command to the switch circuit 32 is not given. For this reason, the output of the adder 33 becomes equal to the voltage set value Vref.
[0066]
As a result, the outputs of the signal holding circuits 25 and 25 ′ become constant, and when the voltage Vac of the AC system bus 1 becomes larger than the AC set value Vref, the output of the adder 33 ′ becomes negative, and is constituted by a proportional integration circuit. The output of the voltage control element 36 is also negative. This value is given to the adders 37 and 37 ′, and the corrected control rates Cmd ′ and Cmq ′ are smaller than the values before correction.
[0067]
The control rate Cm (the square root of the sum of the square of Cmd and the square of Cmq) is a value corresponding to the magnitude of the AC output voltage of the self-excited AC / DC converter 3. Accordingly, when Cmd ′ and Cmq ′ are small values, the AC output voltage of the self-excited AC / DC converter 3 becomes small. Since no other power source is connected to the AC bus 1 and the value of the bus voltage is determined by the output voltage of the self-excited AC / DC converter 3, the output voltage of the self-excited AC / DC converter 3 can be reduced as described above. Thus, the voltage of the AC system bus 1 is also reduced. Conversely, when the voltage level Vac of the AC system bus 1 is smaller than the voltage setting value Vref which is the output of the adder 33, correction is performed so that the values of Cmd ′ and Cmq ′ are increased, and the self-excited AC / DC converter 3 is corrected. And the voltage of the AC system bus 1 also increases.
[0068]
By operating in this way, the voltage of the AC system bus 1 is controlled to be equal to the voltage setting value Vref, and the active power and reactive power output force of the self-excited AC / DC converter 3 are automatically connected. It becomes a value commensurate with the capacity of the load system 18 and the phase adjusting equipment 19. Since the output of the alternating current control circuit 13 is fixed by the signal holding circuits 26 and 26 ', the active power set value Pref, the reactive power set value Qref, and the alternating current control during normal operation given to the alternating current control circuit 13 are used. The operation of circuit 13 is ignored.
[0069]
Furthermore, in the first embodiment, AC current control is performed so that the output of the self-excited AC / DC converter 3 is stabilized. In the state where the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source, the appropriate current setting values of the active power component and the reactive power component are unknown, so in the first embodiment, the d-axis current detection value Id In contrast, the value via the primary delay circuit 26 is used as the d-axis current set value, and the value via the primary delay circuit 26 'is used as the q-axis current detection value Iq as the q-axis current set value.
[0070]
As described above, the output currents Id and Iq are automatically set by fixing Cmd and Cmq, which are the outputs of the AC current control circuit 13 during normal operation, and correcting them with AC voltage control. Since the value is balanced with the load system 18 and the phase adjusting equipment 19, the value itself is used as the current set value.
[0071]
When the circuit breaker 21 is three-phase open, the switch circuits 28 and 28 'are turned on, and the current control elements 29 and 29' are operated, so that the active power component Id and the reactive power component Iq of the converter output current are respectively delayed by the first order. A correction signal that follows a value with less vibration component via the circuits 26 and 26 ′ is output and applied to the adders 30 and 30 ′, so that Cmd ′ and Cmq ′ cause vibrations of active power and reactive power. It is corrected to suppress. The above action is shown in publicly known literature (1997 Institute of Electrical Engineers of Japan / Electric Power / Energy Division Conference No. 320 “Examination of an independent operation system using a self-excited AC / DC converter for DC interconnection (1)”).
[0072]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are larger than the capacity of the self-excited AC / DC converter 3. The operation of will be described.
[0073]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the load system 18 and the phase adjusting equipment 19 are small. The operation is different between the overcurrent detector 35 and the switch circuit 32. When active power and reactive power are supplied to the load system 18 and the phase adjusting equipment 19 having a large capacity, the output current of the self-excited AC / DC converter 3 increases, and the output of the arithmetic circuit 351 in the overcurrent detector 35 increases. Then, the level detector 352 operates.
[0074]
Further, since the circuit breaker 21 is in the three-phase open state and the output of the circuit breaker state monitoring device 24 is also in the “1” state, the output of the AND circuit 353 is also “1”. The value increases and exceeds the level set value of the level detector 355, and a closing command signal is given to the switch circuit 32.
[0075]
As a result, the reduction range ΔVref of the voltage setting value is added to the adder 33 with a negative sign, and the final voltage setting value that is matched with the voltage detection value Vac by the adder 33 ′ is (Vref−ΔVref). . Therefore, the self-excited AC / DC converter 3 is controlled by the voltage control element 36 so that the voltage of the AC system bus 1 becomes a value lower than the normal voltage by ΔVref. Other actions are the same as when the capacity of the load system 18 and the phase adjusting equipment 19 is small.
[0076]
Here, the principle of reducing the output current value of the self-excited AC / DC converter 3 by lowering the AC voltage will be described with reference to FIG. In FIG. 3, when the AC system bus voltage is Vs and the impedance of the load system is Z, the flowing current I is given by the following equation (2).
[0077]
I = Vs / Z (2)
The bus voltage Vs increases as the output voltage Vi of the self-excited AC / DC converter 3 increases, and decreases as the output voltage Vi decreases. When the load system capacity is large, that is, when the impedance Z is small, the current I in the equation (2) becomes large and an overcurrent is generated. In order to suppress this overcurrent I, the impedance Z may be increased or the bus voltage Vs may be decreased. In the first embodiment, the output voltage Vi of the self-excited AC / DC converter 3 is lowered to lower the bus voltage Vs, the current I is reduced, and the overcurrent is suppressed.
[0078]
If operation is performed with the voltage reduced for a long time, a power failure or the like may occur. Eventually, however, it will be necessary to shut down the load system or trip the phase adjusting equipment. If the overcurrent is suppressed by the control of the self-excited AC / DC converter 3 that operates at high speed, the load system that causes a power failure can be minimized.
[0079]
FIG. 4 shows a waveform of a digital simulation result when the first embodiment is applied. In this simulation, the self-excited AC / DC converter 3 is disconnected from the power source from the state where the reverse converter operation (power is supplied to the AC side) with 100% active power while the self-excited AC / DC converter 3 is connected to the AC power source. 2 shows a waveform of the converter output current and the bus voltage of the AC system bus 1 when a capacitor having a capacity 1.5 times larger than the rated current is connected.
[0080]
FIG. 4A shows the characteristics when the overcurrent is detected and the AC voltage set value Vref is reduced from the normal 100% to 70% after switching the control. FIG. These are characteristics when only the control is switched and the AC voltage set value Vref is not reduced. It can be seen that there is an overcurrent suppressing effect by reducing the AC voltage set value Vref.
[0081]
As described above, according to the first embodiment, the self-excited AC / DC converter 3 applied to the DC power transmission system or the DC power supply system is in accordance with the set value given from the central power supply command station during normal operation. When the self-excited AC / DC converter 3 is suddenly disconnected from the AC power supply, the bus voltage of the AC system bus 1 is maintained constant. Control as follows.
[0082]
As a result, the active power and reactive power can be automatically output in accordance with the capacity of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected, and the active power component and reactive power of the output current can be automatically output. By controlling the output current with a value via the first-order lag as a set value for the power component, fluctuations in active power and reactive power can be suppressed and more stable operation can be continued. Further, when the connected load system 18 and the phase adjusting equipment 19 are larger than the capacity of the self-excited AC / DC converter 3 and the output of the converter becomes an overcurrent, the self-excited AC / DC converter is operated so that the AC voltage is lowered. By controlling 3, overcurrent can be suppressed, the self-excited AC / DC converter 3 can be continuously operated, and a power failure can be minimized.
[0083]
Next, a second embodiment of the present invention will be described. FIG. 5 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that a detection signal for the frequency change of the voltage of the AC bus 1 is used as a control switching command signal. is there.
[0084]
That is, instead of the circuit breaker state monitoring device 24 in FIG. 1, an AC voltage detector 38, a frequency deviation detector 39, a level detector 40, an integrator 41 with reset, and a level detector 42 are used as a system state monitoring device. Provide. The AC voltage detector 38 detects the bus voltage of the AC system bus 1, and the frequency deviation detector 39 detects the deviation between the detected frequency of the AC voltage and a preset constant frequency value (for example, the rated frequency of the AC system). Is calculated. The level detector 40 outputs “1” when the given frequency deviation exceeds a certain level, and outputs “0” when the frequency deviation does not exceed the given level, and provides it to the integrator 41 with reset. When the input value is “1”, the integrator 41 with reset integrates it, and when the input value becomes “0”, the output is reset to zero. In the level detector 42, when the value given from the integrator 41 with reset exceeds a preset constant value, an input command is given to the switch circuits 28, 28 ′, 34 as a control switching command signal, and a signal holding circuit A signal holding command is given to 25 and 25 '. The configuration of the other parts is the same as that of the first embodiment shown in FIG.
[0085]
Next, the operation will be described. Since the AC circuit breakers 21 and 21 ′ are normally turned on, the AC system bus 1 is connected to the generator 22 of the power system 23, and the frequency of the AC system bus 1 is also the frequency of the generator 22. Since it is determined by the rotational speed, it is kept at almost the rated value. As a result, the output value of the frequency deviation detector 39 becomes a small value, and the outputs of the level detector 40, the integrator 41 with reset, and the level detector 42 are “0”, respectively. Accordingly, the switch circuit 28, 28 ', 34 is not given an input command, and each switch is opened. Further, since the holding command signal is not given to the signal holding circuits 25 and 25 ′, the signal holding circuits 25 and 25 ′ output the input values Cmd and Cmq as they are. Such an operating state is exactly the same as when the conventional self-excited AC / DC control device shown in FIG. 30 is used.
[0086]
Next, the operation when the circuit breaker 21 is three-phase open will be described. When the circuit breaker 21 is opened in three phases, the AC system bus 1 and the self-excited AC / DC converter 3, the load system 18, and the phase adjusting equipment 19 connected thereto are completely disconnected from the power system 23 including the generator 22. It will be in the state. For this reason, the element which determines the frequency of alternating current system bus-line 1 is lost, and a frequency changes. In addition, as described in the first embodiment, the balance between the capacity of the load system 18 and the phase adjusting equipment 19 and the output of the self-excited AC / DC converter 3 is lost, and an AC overvoltage and a voltage drop occur, resulting in stable operation. Operation may not be possible.
[0087]
Therefore, in the second embodiment, it is detected that the frequency of the bus voltage of the AC system bus 1 fluctuates, and the AC generator 22 to which the self-excited AC / DC converter 3 is connected is disconnected. It is determined that That is, when the frequency of the bus voltage of the AC system bus 1 fluctuates, the output value of the frequency deviation detector 39 becomes a large value, whereby the output of the level detector 40 becomes “1”. If the state where the generator 22 is disconnected continues, this state continues, so that the output value of the integrator 41 increases with time, and when a certain time elapses, the value exceeds the set level of the level detector 42 to detect the level. The device 42 outputs “1”. This signal is given as a closing command to the switch circuits 28, 28 'and 34, and is given as a holding command signal to the signal holding circuits 25 and 25'. Further, when the capacity of the connected load system 18 or phase adjusting equipment 19 is large, the overcurrent detector 35 is operated and the switch circuit 32 is turned on, and the control given to the PWM control circuit 15 by these operations. The rate signals Cmd ′ and Cmq ′ operate in the same manner as in the first embodiment.
[0088]
According to the second embodiment, the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system has active power and invalidity according to set values given from a central power supply command station during normal operation. When operation is performed so as to supply or absorb power and the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source, the frequency of the bus voltage of the AC system bus 1 is continuously maintained during normal operation. Control is performed so as to maintain the AC voltage constant on condition that the value deviates greatly. As a result, the active power and the reactive power having values corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected can be automatically output. Furthermore, the active current component and reactive power component of the output current are controlled by setting the output current with the value via the first-order lag as a set value, thereby suppressing fluctuations in the active power and reactive power, thereby enabling more stable operation. Can continue. Further, when the connected load system or phase adjusting equipment is larger than the capacity of the converter and the converter output becomes an overcurrent, the self-excited AC / DC converter 3 is controlled so as to operate at a low AC voltage. The current can be suppressed, the self-excited AC / DC converter 3 can be continuously operated, and the power failure can be minimized.
[0089]
Next, a third embodiment of the present invention will be described. FIG. 6 is a configuration diagram of the self-excited AC / DC converter control device 47 according to the third embodiment of the present invention. In the third embodiment, the switch circuit 32 and the adder 33 are deleted from the self-excited AC / DC converter control device 3 according to the first embodiment shown in FIG. Is directly provided to the PWM control circuit 15. Since other configurations are the same as those of the first embodiment shown in FIG. 1, the same reference numerals are given to the same elements, and the description thereof is omitted.
[0090]
The overcurrent detector 35 in the third embodiment is used for pulse width control in the PWM control circuit 15 when the AC output current of the self-excited AC / DC converter 3 continuously exceeds a predetermined value for a predetermined time or longer. The sine value for the peak value of the sine wave signal is set to a smaller value than usual. As a result, even when the self-excited AC / DC converter 3 is suddenly disconnected from the generator 22, the AC overvoltage and the voltage drop are prevented, and the active power having a value commensurate with the connected load system and phase adjusting equipment. And the operation of the self-excited AC / DC converter is continued stably while supplying reactive power.
[0091]
FIG. 7 is a configuration diagram of the internal configuration of the PWM control circuit 15 according to the third embodiment. The control rates Cmd ′ and Cmq ′ are input to the arithmetic circuit 151, and the peak value Cm (the square root of the square of Cmd ′ and the square of Cmq ′) of the sine wave signal used in the PWM control is calculated. ) Is converted into a relative phase angle φ with respect to the phase θv of the AC system bus 1.
[0092]
φ = tan ^-1 (Cmq ′ / Cmd ′) (3)
The peak value Cm of the sine wave signal is applied to the sine wave generation circuit 153 via the limiter circuit 152, and the phase angle φ is added to the AC system bus phase θv by the adder 154 to an absolute phase (θv + φ) that changes instantaneously. It is converted and applied to the sine wave generation circuit 153. The sine wave generation circuit 153 generates a sine wave signal that changes instantaneously according to the following equation (4).
[0093]
Cm (t) = Cm · cos (θv (t) + φ) (4)
On the other hand, the carrier wave generation circuit 155 generates a carrier wave having a constant peak value synchronized with the phase θv of the AC system bus 1. Each waveform is given to the level comparison circuit 156, and an on pulse or an off pulse is generated depending on the magnitude relationship thereof, and the semiconductor element of the self-excited AC / DC converter 3 is turned on / off.
[0094]
Here, the limit value used in the limiter circuit 152 is usually a constant value, which is about 90 to 95% of the peak value of the carrier wave. This limiter is provided in order to prevent normal switching when the sine wave peak value becomes large and becomes equal to or higher than the carrier wave peak value.
[0095]
FIG. 8 shows the relationship between each waveform of PWM control and switching timing. The carrier wave oscillates as a triangular wave having a constant peak value at a higher frequency than the sine wave. The sine wave is a signal corresponding to the fundamental wave component of the converter output voltage, and uses a peak value corresponding to the output voltage to be generated. The sine wave is matched with the carrier wave, and the switching timing is determined by the magnitude relationship.
[0096]
Here, when the peak value of the sine wave is smaller than that of the carrier wave, as shown in FIG. 8A, for example, if the carrier wave has a frequency three times that of the sine wave, three times each in one cycle of the sine wave. On / off is performed. Next, when the peak value of the sine wave becomes larger than the carrier wave, switching is performed once each on and off as shown in FIG. 8B, and normal operation is not performed. Therefore, the peak value of the sine wave is limited to a value that is slightly smaller than the carrier wave, for example, 90 to 95% of the carrier wave peak value, and control is performed so that switching is performed three times each as a waveform as shown in FIG. .
[0097]
Here, in the PWM control circuit 15 shown in FIG. 7, a switch circuit 157 is provided, and a value of about 90 to 95% of the carrier wave peak value used at normal time is given to one of the input terminals as Cmax1. For the other input terminal, a smaller value such as 70% of the carrier wave is given as Cmax2. When an overcurrent is detected by the overcurrent detector 35, the switch circuit 157 is switched to select Cmax2, which is set as a limit value used in the limiter circuit 152.
[0098]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is exactly the same as in the first embodiment. The PWM control circuit 15 uses Cmax1, which is about 90 to 95% of the carrier wave, as a limit value for the sine wave signal.
[0099]
Next, the operation when the circuit breaker 21 is opened in three phases in the AC system and the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are larger than the converter capacity will be described. .
[0100]
The operations of the switch circuits 28, 28 ', 34 and the signal holding circuits 25, 25' are the same as when the load system 18 and the phase adjusting equipment 19 are small. The operation is different between the overcurrent detector 35, the switch circuit 157 in the PWM control circuit 15, and the limiter circuit 152. When trying to supply active power and reactive power to the load system 18 and the phase adjusting equipment 19 having a large capacity, the converter output current increases, and the level detector 352 of the overcurrent detector 35 in FIG. 2 operates. Since the output of the circuit breaker state monitoring device 24 is also in the “1” state, the output of the AND circuit 353 is also “1”. If this state continues for a certain time, the output value of the integrating circuit 354 increases and the level setting of the level detector 355 is performed. When the value is exceeded, a switching command signal is given to the switch circuit 157 in the PWM control circuit 15.
[0101]
As a result, the limit value for the PWM sine wave signal peak value used in the limiter circuit 152 is switched to a value Cmax2 smaller than normal, and the sine wave signal generated by the sine wave generation circuit 153 is limited to a small value. Since this signal is proportional to the converter output voltage, the converter output voltage is limited to a small value.
[0102]
Here, as described in the first embodiment, the converter output current value can be reduced by lowering the AC voltage. If operation is performed with the voltage reduced for a long time, a power failure or the like may occur. Therefore, it is necessary to shut off the load system 18 or trip the phase adjusting equipment 19 until the operation is performed. In the meantime, if the overcurrent is suppressed by the control of the self-excited AC / DC converter 3 operating at high speed, the load system 18 to be interrupted can be minimized.
[0103]
FIG. 9 shows a waveform of a digital simulation result when the third embodiment is applied. In this simulation, the self-excited AC / DC converter 3 is disconnected from the power source from the state where the reverse converter operation (power is supplied to the AC side) with 100% active power while the self-excited AC / DC converter 3 is connected to the AC power source. It shows the waveform of the converter output current and the AC system bus voltage when a reactor having a capacity 2.5 times larger than the rated current is connected.
[0104]
FIG. 9A shows the characteristics when the overcurrent is detected and the PWM sine wave limit is reduced from the normal 95% to 50% after switching the control. FIG. 9B shows the control. The characteristic is shown when only the switching is performed and the limiter value is not reduced. From these characteristic curves, the overcurrent suppression effect by reducing the limiter value is clear.
[0105]
According to the third embodiment, the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system has active power and invalidity according to set values given from a central power supply command station during normal operation. By operating to supply or absorb power, and when the self-excited AC / DC converter 3 suddenly becomes disconnected from the AC power source, by controlling to maintain the voltage of the AC system bus 1 constant, Active power and reactive power corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected can be automatically output, and the active power component and reactive power component of the output current can be further output. On the other hand, by controlling the output current using the value via the first-order delay as a set value, fluctuations in active power and reactive power can be suppressed, and more stable operation can be continued. Furthermore, when the connected load system 18 and the phase adjusting equipment 19 are larger than the capacity of the self-excited AC / DC converter 3 and the converter output becomes an overcurrent, the self-excited AC / DC converter 3 is operated so that the AC voltage is lowered. By controlling the overcurrent, the overcurrent can be suppressed, the self-excited AC / DC converter 3 can be continuously operated, and the power failure can be minimized.
[0106]
In the third embodiment as well, instead of using the state monitoring signals of the circuit breakers 21 and 21 ′ as a means for detecting that the self-excited AC / DC converter 3 is disconnected from the AC power source, frequency fluctuations occur. You may make it detect that it deviated from the range which continued more than fixed time. In this case, the same effect can be obtained.
[0107]
Further, in the PWM control circuit 15 of FIG. 7, instead of placing the limiter circuit 152 at the input portion of the sine wave generation circuit 153, a similar limiter circuit is provided for the output of the sine wave generation circuit 153 and is given from the switch circuit 157. The same effect can be obtained even when the peak value of the sine wave signal is limited using the limit value Cmax1 or Cmax2 that has been set.
[0108]
Next, a fourth embodiment of the present invention will be described. FIG. 10 is a configuration diagram of a main part of a self-excited AC / DC converter control device 47 according to the fourth embodiment. The fourth embodiment is a self-excited AC / DC converter control device according to the first embodiment shown in FIG. 1, and provides the output of the overcurrent detector 35 to the switch circuit 32 as a closing command signal. As in the third embodiment, the output of the overcurrent detector 35 is also given as a switching command to the switch circuit 157 in the PWM control circuit 15. Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same elements, and descriptions thereof are omitted.
[0109]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is the same as in the first embodiment.
[0110]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are larger than the capacity of the self-excited AC / DC converter 3. The operation of will be described.
[0111]
The operations of the switch circuits 28, 28 ', 34 and the signal holding circuits 25, 25' are the same as when the load system 18 and the phase adjusting equipment 19 are small. The operation is different from that when the capacity of the load system 18 and the phase adjusting equipment 19 is small. The switch circuit 32, the adders 33 and 33 ′, the overcurrent detector 35, the switch circuit 157 in the PWM control circuit 15, and the limiter circuit. 152. When trying to supply active power and reactive power to the load system 18 and the phase adjusting equipment 19 having a large capacity, the output current of the self-excited AC / DC converter 3 increases, the overcurrent detector 35 operates, and the switch circuit 32 is turned on. The
[0112]
As a result, the value given to the adder 33 ′ used as the AC voltage setting value decreases from the normal Vref to (Vref−ΔVref). Further, the overcurrent detector 35 operates to switch the switch circuit 157 in the PWM control circuit 15, and the limit value used in the limiter circuit 152 is switched from the normal Cmax1 to a smaller value Cmax2. .
[0113]
Accordingly, the voltage control element 36 performs correction control so that the voltage of the AC system bus 1 becomes a value smaller than the rated value, and the PWM control circuit 15 limits the peak value of the sine wave signal so as not to exceed Cmax2. The voltage of the AC system bus 1 can be lowered, and the output current value of the self-excited AC / DC converter 3 can be reduced.
[0114]
That is, as a measure for operating with the AC voltage lowered, the voltage setting value used in AC voltage control is reduced in the first embodiment and the second embodiment, and the PWM sine is used in the third embodiment. While the crest value of the wave signal is limited to a small value, the fourth embodiment performs both of them. When the connected load system 18 and the phase adjusting equipment 19 are capacitive as a whole, that is, the amount of the capacitor is large, it is more effective to reduce the voltage set value used in the AC voltage control as a measure for reducing the voltage. On the other hand, when the load system 18 and the phase adjusting equipment 19 connected in reverse are inductive as a whole, that is, when the reactor amount is large, a method of limiting the PWM sine wave signal to be small as a measure for reducing the voltage is more effective. is there.
[0115]
For this reason, when the phase adjusting equipment 19 installed in the vicinity of the self-excited AC / DC converter 3 is concentrated on either side, a sufficient effect can be obtained by one of the operations. If both operations are performed as in the fourth embodiment so that the phase-adjusting equipment 19 having either characteristic can be handled, the overcurrent suppression by the voltage reduction can be ensured. Increases nature.
[0116]
According to the fourth embodiment, the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system has active power and invalidity according to set values given from a central power supply command station during normal operation. By operating to supply or absorb power, and when the self-excited AC / DC converter 3 is suddenly disconnected from the AC power supply, control is performed to maintain the bus voltage of the AC system bus 1 constant. The active power and the reactive power having values corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 can be automatically output.
[0117]
Furthermore, the active current component and reactive power component of the output current are controlled by setting the output current with the value via the first-order lag as a set value, thereby suppressing fluctuations in the active power and reactive power, thereby enabling more stable operation. Can continue. In addition, when the connected load system 18 and the phase adjusting equipment 19 are larger than the capacity of the self-excited AC / DC converter 3 and the output of the self-excited AC / DC converter 3 becomes an overcurrent, the AC voltage is lowered to operate automatically. By controlling the excitation-type AC / DC converter 3, an overcurrent can be suppressed, and the self-excited-type AC / DC converter 3 can be continuously operated, and a power failure can be minimized.
[0118]
In the fourth embodiment as well, instead of using the state monitoring signals of the circuit breakers 21 and 21 ′ as a means for detecting that the self-excited AC / DC converter 3 is disconnected from the AC power source, frequency fluctuations occur. You may make it detect that it deviated from the range which continued more than fixed time. In this case, the same effect can be obtained.
[0119]
Next, a fifth embodiment of the present invention will be described. FIG. 11 is a configuration diagram of a main part of a self-excited AC / DC converter control device 47 according to the fifth embodiment. In the fifth embodiment, a level detector 43, an AND circuit 44, a NOT circuit 45, and an AND circuit 46 are added to the self-excited AC / DC converter control device according to the fourth embodiment shown in FIG. It is. Since the other configuration is the same as that of the fourth embodiment shown in FIG. 10, the same reference numerals are given to the same elements, and the description thereof is omitted. The internal configuration of the overcurrent detector 35 is the same as that described in FIG. 2, and the internal configuration of the PWM control circuit 15 is the same as that described in FIG.
[0120]
The level detector 43 receives Iq, which is a reactive power component of the output current of the self-excited AC / DC converter 3, at the output of the dq axis conversion circuit 14, and is a positive value whether or not it is greater than zero. Or negative value. Here, when Iq> 0, the reactive power output indicates capacitive, and when Iq <0, the reactive power output indicates inductive.
[0121]
When Iq> 0 (capacitive case), the level detector 43 outputs “1” and inputs it to the AND circuit 44 and the NOT circuit 45. The NOT circuit 45 inverts the 1/0 signal and applies it to the AND circuit 46. On the other hand, when an overcurrent is detected by the overcurrent detector 35, the signal “1” is given to the AND circuit 44 and the AND circuit 46, and when both input signals are “1” in the AND circuit 44, the switch circuit 32. Is given an input command. The AND circuit 46 gives a switching command signal to the switch circuit 157 in the PWM control circuit 15 when both of the input signals are “1”.
[0122]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is the same as that in the fourth embodiment.
[0123]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the capacities of the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are compared with the capacities of the self-excited AC / DC converter 3. The operation when it is large will be described.
[0124]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the capacity of the load system 18 or the phase adjusting equipment 19 is small. When the capacity of the load system 18 and the phase adjusting equipment 19 is large and the output of the self-excited AC / DC converter 3 becomes an overcurrent, the output of the overcurrent detector 35 becomes “1”. When a capacitor is connected as the phase adjusting equipment 19, the output current becomes capacitive (advanced current), and the reactive power component current that is the output of the dq axis conversion circuit 14 becomes Iq> 0.
[0125]
As a result, the output of the level detector 43 is “1”, and the output of the NOT circuit 45 for inverting it is “0”, which are given to the AND circuits 44 and 46, respectively. Since the output of the overcurrent detector 35 which is the other input signal of each AND circuit is “1”, the output of the AND circuit 44 is “1” and the output of the AND circuit 46 is “0”. Accordingly, the switch circuit 32 is turned on to reduce the AC current set value. Switching of the switch circuit 157 in the PWM control circuit 15 is not performed.
[0126]
On the other hand, when a reactor is connected as the phase adjusting equipment 19, the output current becomes inductive (lag current), and the reactive power component current that is the output of the dq axis conversion circuit 14 becomes Iq <0. As a result, the output of the level detector 43 is “0”, and the output of the NOT circuit 45 for inverting it is “1”, which are given to the AND circuits 44 and 46, respectively. Since the output of the overcurrent detector 35 which is the other input signal of each of the AND circuits 44 and 46 is “1”, the output of the AND circuit 44 is “0” and the output of the AND circuit 46 is “1”. It becomes.
[0127]
As a result, switching of the switch circuit 157 in the PWM control circuit 15 is performed, and the limit value for the PWM sine wave signal peak value is switched to a value Cmax2 that is smaller than usual, and the PWM sine wave is limited to a small value. Further, the switch circuit 32 of FIG. 11 is not turned on, and the AC voltage set value is not switched.
[0128]
As a result, when the output of the self-excited AC / DC converter 3 is a capacitive overcurrent, the AC voltage set value used in the voltage control element 36 is reduced so that the voltage of the AC system bus 1 becomes smaller than usual. When the output of the self-excited AC / DC converter 3 is an inductive overcurrent, the limit value for the peak value of the sine wave signal used in the PWM control circuit 15 is switched to a limit value smaller than normal. The voltage of the AC system bus 1 can be lowered by an appropriate method depending on whether the output overcurrent of the converter 3 is capacitive or inductive, and the output current value of the self-excited AC / DC converter 3 can be reduced.
[0129]
According to the fifth embodiment, the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system has active power and invalidity according to set values given from a central power supply command station during normal operation. By operating to supply or absorb power, and when the self-excited AC / DC converter 3 is suddenly disconnected from the AC power supply, control is performed to maintain the bus voltage of the AC system bus 1 constant. The active power and the reactive power can be automatically output with values corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected.
[0130]
Furthermore, the active current component and reactive power component of the output current are controlled by setting the output current with the value via the first-order lag as a set value, thereby suppressing fluctuations in the active power and reactive power, thereby enabling more stable operation. Can continue. Further, when the connected load system 18 or the phase adjusting equipment 19 generates an overcurrent larger than the capacity of the self-excited AC / DC converter 3, the self-excited AC / DC converter 3 is controlled so as to operate at a lower AC voltage. By suppressing the overcurrent, the self-excited AC / DC converter 3 can be continuously operated and the power failure can be minimized.
[0131]
In the fifth embodiment as well, instead of using the state monitoring signals of the circuit breakers 21 and 21 ′ as a means for detecting that the self-excited AC / DC converter 3 is disconnected from the AC power source, frequency fluctuations occur. You may make it detect that it deviated from the range which continued more than fixed time. In this case, the same effect can be obtained.
[0132]
Further, in order to determine whether the output current of the self-excited AC / DC converter 3 is capacitive or inductive, a signal input to the level detector 43 is 1 instead of the output Iq of the dq axis conversion circuit 14. Even if the output signal of the next delay circuit 26 'is used, the same effect can be obtained.
[0133]
Next, a sixth embodiment of the present invention will be described. FIG. 12 is a configuration diagram of a main part of a self-excited AC / DC converter control device 47 according to the sixth embodiment. In the sixth embodiment, in the self-excited AC / DC converter control device according to the first embodiment shown in FIG. 1, a switch circuit 32 ′ is added, and voltage is set in each of the switch circuit 32 and the switch circuit 32 ′. The value reduction values ΔVref1 and ΔVref2 are given, and the input is performed by separate input command signals a and b from the overcurrent detector 35. Since other configurations are the same as those of the first embodiment shown in FIG. 1, the same reference numerals are given to the same elements, and the description thereof is omitted.
[0134]
FIG. 13 is a block diagram showing an internal configuration of the overcurrent detector 35 in the sixth embodiment. The level detector 352 is different from the overcurrent detector 35 in the first embodiment shown in FIG. ', An AND circuit 353', an integrator 354 ', and a level detector 355' are added. In the level detectors 352 and 352 ′, different levels of current values I1 and I2 (I1 <I2) are set, and when the magnitude of the current obtained by the arithmetic circuit 351 exceeds each set level. It is assumed that “1” is given to the AND circuits 353 and 353 ′. The other configuration in FIG. 13 is the same as that of the overcurrent detector 35 shown in FIG.
[0135]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is the same as in the first embodiment.
[0136]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the capacities of the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are compared with the capacities of the self-excited AC / DC converter 3. The operation when it is large will be described.
[0137]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the capacity of the load system 18 or the phase adjusting equipment 19 is small. The capacity of the load system 18 and the phase adjusting equipment 19 is large, the output current I of the self-excited AC / DC converter 3 exceeds the set level I1 of the level detector 352 of the overcurrent detector 35, and the set level I2 of the level detector 352 ′. If it is smaller (I2>I> I1), when this state continues for a certain time, the level detector 355 in FIG. 13 operates and the output signal a becomes “1”. On the other hand, since the level detector 352 ′ does not operate, the level detector 355 ′ does not operate, and the signal b remains “0”.
[0138]
Thereby, in the sixth embodiment shown in FIG. 12, the switch circuit 32 is turned on and the switch circuit 32 ′ is left open. When the switch circuit 32 is turned on, ΔVref1 is added to the adder 33 with a negative sign. Therefore, the AC voltage setting value used in the voltage control element 36 is based on Vref when no overcurrent occurs. Is also a small value (Vref−ΔVre1), and the control is performed so that the voltage of the AC system bus 1 becomes a value smaller than normal.
[0139]
The capacities of the load system 18 and the phase adjusting equipment 19 are larger, and the output current I of the self-excited AC / DC converter 3 is set to the set level I1 of the level detector 352 of the overcurrent detector 35 and the set level I2 of the level detector 352 ′. When both of these are exceeded (I>I2> I1), when this state continues for a certain period of time, both level detectors 355 and 355 ′ in FIG. 13 operate, and the output signals a and b become “1”.
[0140]
As a result, both the switch circuit 32 and the switch circuit 32 ′ of FIG. 12 are turned on. When the switch circuits 32 and 32 ′ are turned on, ΔVref1 and ΔVref2 are added to the adder 33 with a negative sign, so that the AC voltage setting value used in the voltage control element 36 is I2>I> I1 The control is performed so that the value becomes smaller (Vref−ΔVre1−ΔVref2) than the case, and the AC voltage further decreases.
[0141]
As described with reference to FIG. 3, the output current I of the self-excited AC / DC converter 3 is given by equation (2). Since the impedance value Z decreases as the capacity of the load system 18 and the phase adjusting equipment 19 increases, the voltage Vs needs to be decreased according to Z when the current I is to be suppressed to a certain value or less. When the self-excited AC / DC converter control device according to the sixth embodiment is used, the smaller the AC voltage set value is used as the capacity of the load system 18 and the phase adjusting equipment 19 is larger, the self-excited AC / DC converter 3 overcurrent is appropriately suppressed.
[0142]
FIG. 14 is a configuration diagram illustrating another example of the overcurrent detector 35 used in the self-excited AC / DC converter control device according to the sixth embodiment. The overcurrent detector 35 shown in FIG. 14 is obtained by adding a level detector 355 ″ to the overcurrent detector 35 according to the first embodiment shown in FIG.
[0143]
The level detectors 355 and 355 ″ are set with different time periods t1 and t2 (t1 <t2), respectively, and the output of the integrating circuit 354, that is, the overcurrent exceeds the set level of the level detector 352. When the length of time exceeds each set level, “1” is output.
[0144]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is exactly the same as in the first embodiment.
[0145]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the capacities of the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are compared with the capacities of the self-excited AC / DC converter 3. The operation when it is large will be described.
[0146]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the capacity of the load system 18 or the phase adjusting equipment 19 is small. When the capacity of the load system 18 or the phase adjusting equipment 19 is large and the output current I of the self-excited AC / DC converter 3 exceeds the set level of the level detector 352 of the overcurrent detector 35, this state is detected by the level detector 355. If the set time t1 or more continues, the output signal a becomes “1”.
[0147]
As a result, the switch circuit 32 shown in FIG. 12 is turned on and ΔVref1 is added to the adder 33 with a negative sign, so that no overcurrent is generated in the AC voltage setting value used in the voltage control element 36. In this case, the control is performed so that the value of (Vref−ΔVre1) is smaller than Vref in the case, and the voltage of the AC system bus 1 is lowered.
[0148]
If the voltage reduction width ΔVref1 is sufficient for suppressing overcurrent, this operation eliminates the overcurrent, and the output of the level detector 352 in FIG. 14 becomes “0”. As a result, the output of the integrator 354 does not become a larger value. Therefore, the level detector 355 ″ does not operate, and the operation is continued with the AC voltage set value being (Vref−ΔVref1).
[0149]
On the other hand, if the voltage reduction width ΔVref1 is insufficient for overcurrent suppression, the overcurrent state continues even if this operation is performed, and the output of the level detector 352 in FIG. 14 remains “1”. As a result, the output of the integrator 354 continues to increase, the level detector 355 ″ operates, the output becomes “1”, and an input command is given to the switch circuit 32 ′ in FIG. 12 as the output signal b. When the overcurrent detector 35 operates as described above, the AC voltage set value further decreases, and the operation is continued in the state of (Vref−ΔVref1−ΔVref2). Thereby, since the alternating voltage setting value of a small value is used, so that the capacity | capacitance of the load system 18 or the phase adjusting equipment 19 is large, the overcurrent of the self-excited AC / DC converter 3 is suppressed appropriately.
[0150]
FIG. 15 is a block diagram showing still another example of the overcurrent detector in the self-excited AC / DC converter control device according to the sixth embodiment of the present invention. The overcurrent detector 35 shown in FIG. 15 is obtained by adding an AND circuit 356, an integrator 357, and a level detector 358 to the overcurrent detector 35 according to the first embodiment shown in FIG. is there. The outputs of the AND circuit 353 and the level detector 355 are input to the AND circuit 356, and the result is output as the input command signal b to the switch circuit 32 ′ in FIG. 12 via the integrator 357 and the level detector 358. .
[0151]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is exactly the same as in the first embodiment.
[0152]
Next, when the circuit breaker 21 is opened in three phases in the AC system, the capacities of the load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are compared with the capacities of the self-excited AC / DC converter 3. The operation when it is large will be described.
[0153]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the capacity of the load system 18 or the phase adjusting equipment 19 is small. When the capacity of the load system 18 or the phase adjusting equipment 19 is large and the output current I of the self-excited AC / DC converter 3 exceeds the set level of the level detector 352 of the overcurrent detector 35, this state is detected by the level detector 355. When the set time is continued, the output signal a becomes “1”.
[0154]
Thereby, the switch circuit 32 of FIG. 12 is turned on, and ΔVref1 is added to the adder 33 with a negative sign, so that the AC voltage set value used in the voltage control element 36 is when no overcurrent has occurred. Control is performed so that the voltage of the AC system bus 1 is lowered because the value is smaller than Vref of (Vref−ΔVre1).
[0155]
If the voltage reduction width ΔVref1 is sufficient for suppressing overcurrent, this operation eliminates the overcurrent, and the outputs of the level detector 352 and the AND circuit 353 in FIG. 15 become “0”. As a result, the outputs of the AND circuit 356, the integrator 357, and the level detector 358 are also "0", and no input command is given to the switch circuit 32 '. Therefore, the operation is continued with the AC voltage setting value being (Vref−ΔVref1).
[0156]
On the other hand, if the voltage reduction width ΔVref1 is insufficient for overcurrent suppression, the overcurrent state continues even if this operation is performed, and the output of the level detector 352 in FIG. 15 remains “1”. As a result, the outputs of the AND circuits 353 and 356 continue to be “1”, the level detector 358 operates and the output becomes “1”, and an input command is sent to the switch circuit 32 ′ in FIG. Given. When the overcurrent detector 35 operates as described above, the AC voltage set value further decreases, and the operation is continued in the state of (Vref−ΔVref1−ΔVref2). As a result, the larger the capacity of the load system 18 and the phase adjusting equipment 19 is, the smaller the AC voltage set value is used, so that the converter overcurrent is appropriately suppressed.
[0157]
According to the sixth embodiment, the self-excited AC / DC converter applied to the DC power transmission system or the DC power supply system has active power and reactive power according to the set values given from the central power supply command center during normal operation. When the self-excited AC / DC converter 3 is suddenly disconnected from the AC power supply, by controlling to maintain the bus voltage of the AC system bus 3 constant, It is possible to automatically output active power and reactive power corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected.
[0158]
Furthermore, the active current component and reactive power component of the output current are controlled by setting the output current with the value via the first-order lag as a set value, thereby suppressing fluctuations in the active power and reactive power, thereby enabling more stable operation. Can continue. Further, when the connected load system 18 and the phase adjusting equipment 19 generate an overcurrent larger than the capacity of the self-excited AC / DC converter 3, the AC is exchanged at a rate corresponding to the capacity of the load system 18 and the phase adjusting equipment 19. By controlling the self-excited AC / DC converter 3 so as to operate at a lower voltage, the overcurrent can be suppressed, the operation of the self-excited AC / DC converter 3 can be continued, and a power failure can be minimized.
[0159]
Also in the sixth embodiment, as a means for detecting that the self-excited AC / DC converter 3 is disconnected from the AC power supply, frequency fluctuations are used instead of using the state monitoring signals of the circuit breakers 21 and 21 ′. You may make it detect that it deviated from the range which continued more than fixed time. In this case, the same effect can be obtained.
[0160]
Further, in order to reduce the voltage setting value according to the capacity of the load system 18 and the phase adjusting equipment 19, the value is switched according to the magnitude of the overcurrent, or the value is switched according to the overcurrent duration. However, the same effect can be obtained by combining both.
[0161]
Next, a seventh embodiment of the present invention will be described. FIG. 16 is a configuration diagram of a main part of a self-excited AC / DC converter control device 47 according to the seventh embodiment. In the seventh embodiment, in the self-excited AC / DC converter control device according to the third embodiment shown in FIG. 6, two signals a and b are supplied to the PWM control circuit 15 from the overcurrent detector 35. It is what I did. Here, as the overcurrent detector 35, any one of those shown in FIGS. 13, 14, and 15 is used.
[0162]
On the other hand, FIG. 17 is a block diagram of the PWM control circuit 15 in the seventh embodiment shown in FIG. 16, and a logical operation circuit 158 is different from the PWM control circuit 15 shown in FIG. 7 in the third embodiment. And, instead of the switch circuit 157 having two terminals, limit values Cmax1, Cmax2, and Cmax3 (Cmax1>Cmax2> Cmax3) having different values are given to the three input terminals X, Y, and Z, respectively. The switch circuit 157 ′ is used.
[0163]
The internal logic of the logical operation circuit 158 is shown in FIG. As shown in FIG. 18A, the input signal b is supplied to the NOT circuit 158A, and the input signal a and the output of the NOT circuit 158A are supplied to the AND circuit 158B. Further, the AND circuit 158B and the input signal b are supplied to the OR circuit 158C, and the output of the OR circuit 158C is supplied to the NOT circuit 158D.
[0164]
FIG. 18B shows the selection state of the terminals X, Y, Z with respect to the input signals a, b. When the output of the NOT circuit 158D is “1”, the terminals X, AND of the switch circuit 157 ′ are shown. When the output of the circuit 158B is “1”, when the value of the terminal Y of the switch circuit 157 ′ and the value of the input signal b is “1”, the switch circuit 157 ′ is selected so as to select the terminal Z of the switch circuit 157 ′. Give a directive.
[0165]
Next, the operation will be described. The load system 18 and the phase adjusting equipment 19 connected to the self-excited AC / DC converter 3 are smaller than the capacity of the self-excited AC / DC converter 3 at the normal time and when the circuit breaker 21 is opened in the AC system. The operation in this case is the same as in the third embodiment.
[0166]
Next, the operation when the circuit breaker 21 in the AC system is three-phase open and the capacity of the load system and the phase adjusting equipment connected to the converter is larger than the converter capacity will be described.
[0167]
The operations of the switch circuits 28, 28 ′, 34 and the signal holding circuits 25, 25 ′ are the same as when the capacity of the load system 18 or the phase adjusting equipment 19 is small. The capacities of the load system 18 and the phase adjusting equipment 19 are large, and the output current I of the self-excited AC / DC converter 3 has exceeded the set level of the level detector 352 of the overcurrent detector 35 in FIGS. In this case, as described in the sixth embodiment, the signal a is “1”.
[0168]
Furthermore, if the overcurrent is large, or if the overcurrent cannot be sufficiently suppressed even if the AC voltage set value is reduced to some extent, the signal b also becomes “1”. When the signals a and b perform the above operation, as shown in FIG. 18B, in the logic operation circuit 158, when both the signal a and the signal b are “0”, that is, when no overcurrent is generated, the switch The terminal X of the circuit 157 ′ is selected, the signal a is “1”, the signal b is “0”, that is, an overcurrent is generated, but it is equal to or lower than the set level of the level detector 352 ′ of FIG. When the overcurrent is suppressed by reducing the set value to (Vref−ΔVref1), the terminal Y of the switch circuit 157 ′ is selected, and both the signal a and the signal b are “1”, that is, an overcurrent is generated. Is over the set level of the level detector 352 ′ of FIG. 13, or if the overcurrent is not suppressed even if the voltage set value is reduced to (Vref−ΔVref1), the terminal Z of the switch circuit 157 ′ is selected. Signal To, give to the switch circuit 157 '.
[0169]
Since the limit value Cmax1 of PWM sine wave used in the normal operation state, Cmax2 smaller than that, and Cmax3 smaller than that are given to the terminals X, Y, and Z of the switch circuit 157 ′, the PWM sine wave The high value is limited to a value corresponding to the magnitude of the overcurrent.
[0170]
As described with reference to FIG. 3, the output current I of the self-excited AC / DC converter 3 is given by equation (2). Since the impedance value Z decreases as the capacity of the load system 18 and the phase adjusting equipment 19 increases, the voltage Vs needs to be reduced according to the impedance value Z when the current I is to be suppressed to a certain value or less. In the seventh embodiment, as the capacity of the load system 18 and the phase adjusting equipment 19 is larger, the peak value of the PWM sine wave, that is, the output voltage of the self-excited AC / DC converter 3 is limited to a smaller value. The overcurrent of the AC / DC converter 3 is appropriately suppressed.
[0171]
In the seventh embodiment as well, instead of using the state monitoring signals of the circuit breakers 21 and 21 ′ as a means for detecting that the self-excited AC / DC converter 3 is disconnected from the AC power source, frequency fluctuations occur. You may make it detect that it deviated from the range which continued more than fixed time. In this case, the same effect can be obtained.
[0172]
Further, in order to reduce the PWM sine wave signal peak value limiter according to the capacity of the load system 18 and the phase adjusting equipment 19, the reduction value is switched depending on the magnitude of the overcurrent or the duration of the overcurrent. However, the same effect can be obtained by combining both of these.
[0173]
Moreover, as means for reducing the AC voltage, the voltage setting is made by reducing both the voltage setting value and the PWM sine wave limit value, or whether the output current of the self-excited AC / DC converter 3 is capacitive or inductive. The same effect can be obtained as a method for selecting a value reduction or a PWM sine wave limit value reduction.
[0174]
According to the seventh embodiment, the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system has active power and reactive power according to set values given from a central power supply command station during normal operation. When the self-excited AC / DC converter 3 is suddenly disconnected from the AC power supply, by controlling to keep the bus voltage of the AC system bus 1 constant, It is possible to automatically output active power and reactive power corresponding to the capacities of the load system 18 and the phase adjusting equipment 19 to which the self-excited AC / DC converter 3 is connected.
[0175]
Furthermore, by controlling the output current using the value via the first-order lag as the set value for the active power component and reactive power component of the output current, the fluctuation of the active power and reactive power is suppressed, and more stable operation is achieved. Can continue.
[0176]
Further, when the connected load system 18 and the phase adjusting equipment 19 generate an overcurrent larger than the capacity of the self-excited AC / DC converter 3, the AC is exchanged at a rate corresponding to the capacity of the load system 18 and the phase adjusting equipment 19. By controlling the self-excited AC / DC converter 3 so as to operate at a lower voltage, the overcurrent can be suppressed, the operation of the self-excited AC / DC converter 3 can be continued, and a power failure can be minimized.
[0177]
Next, an eighth embodiment of the present invention will be described. FIG. 19 is a configuration diagram of a circuit breaker circuit control device according to the eighth embodiment.
[0178]
A self-excited AC / DC converter 3 is connected to the AC system bus 1 via a transformer 2 and is controlled by a self-excited AC / DC converter controller 47 to operate. The self-excited AC / DC converter control device 47 is applied with any one of the first to seventh embodiments and is disconnected from the power supply system 23 by opening the circuit breakers 21 and 21 '. The self-excited AC / DC converter 3 continues to be operated even if it becomes.
[0179]
Here, in the power system of the eighth embodiment, the primary side (AC system bus 1 side) of the transformer 17 to which the phase adjusting equipment 19 is connected is Y-connected, and the neutral point and the ground are interrupted. A harmonic filter 50 is installed via a device 49. The circuit breaker 49 is normally open. As shown in FIG. 20, the harmonic filter 50 is a combination of a capacitor C, a reactor L, and a resistor R, and has a high-pass type shown in FIG. 20 (a) or a tuned type configuration shown in FIG. 20 (b). is there. These are generally used for suppressing harmonics in an electric power system, and pass harmonic currents of the order n shown in the following equation (5) to suppress harmonic voltages.
[0180]
[Expression 2]

[0181]
The circuit breaker state monitoring device 24 gives a “1” signal to the circuit breaker control circuit 48 when the circuit breaker 21 or the circuit breaker 21 ′ is in a three-phase open state. On the other hand, a signal indicating that the self-excited AC / DC converter 3 is in operation is supplied from the self-excited AC / DC converter control device 47 to the circuit breaker control circuit 48. The circuit breaker control circuit 48 gives a closing command signal to the circuit breaker 49 on condition that the signal from the circuit breaker state monitoring circuit 24 is “1” and the self-excited AC / DC converter 3 is in operation.
[0182]
Next, the operation will be described. Since the AC circuit breakers 21 and 21 ′ are normally turned on, the AC system bus 1, the self-excited AC / DC converter 3, the transformer 17, etc. are connected to a power system 23 including a plurality of generators 22. Yes. Since a three-phase sine wave AC voltage is applied from the power source, the harmonic voltage of the AC system bus 1 is small. Since the output of the circuit breaker state monitoring device 24 is “0”, the circuit breaker control circuit 48 does not give a closing command to the circuit breaker 49, the circuit breaker 49 is in an open state, and the transformer 17 is not neutral on the primary side. Operated in a grounded state. The harmonic filter 50 is disconnected from the circuit.
[0183]
Next, the operation when the circuit breaker 21 suddenly becomes three-phase open in the AC system while the self-excited AC / DC converter 3 is operating will be described. The circuit breaker 21 is in an open state, and the capacity of the load system 18 and the phase adjusting equipment 19 connected to the output of the self-excited AC / DC converter 3 becomes temporarily unbalanced, so that fluctuation occurs and the AC system bus In the circuit connected to 1, harmonic distortion occurs. Among the generated harmonics, those of the positive phase component and the negative phase component are suppressed by the self-excited AC / DC converter 3 performing current control so as to suppress the vibration of the dq axis current.
[0184]
However, the harmonics of the zero-phase component of the voltage of the AC system bus 1 cannot be suppressed by the self-excited AC / DC converter 3. In general, the zero-phase circuit between the primary side and the secondary side of the transformer is cut off, and is connected to the primary side by the self-excited AC / DC converter 3 connected to the secondary side of the transformer 2. This is because the zero phase circuit of the AC system bus 1 cannot be affected. Therefore, the generated zero-phase harmonic circulates through a leakage capacitance or the like and is attenuated little by little due to the resistance of the circuit, so that the duration time is long.
[0185]
Here, in the circuit breaker circuit control device according to the eighth embodiment shown in FIG. 19, when the output of the circuit breaker state monitoring device 24 becomes “1”, the circuit breaker control circuit 48 controls the circuit breaker 49. Input command is given. As a result, the harmonic filter 50 is input to the primary neutral point of the transformer 17. The voltage generated at the neutral point of the Y-connected circuit is a zero-phase voltage. When the harmonic filter 50 is inserted into the neutral point, the current of the zero-phase harmonic component flows into the harmonic filter 50 and its resistance component. Zero-phase harmonics are eliminated by the R damping effect.
[0186]
FIG. 21 shows the result of verifying the zero-phase harmonic suppression effect by introducing the harmonic filter 50 at the neutral point of the transformer through simulation. FIG. 21A shows a case where no countermeasure is taken, and after the power source is disconnected, the generated harmonic of the bus voltage of the AC bus 1 continues. In this case, when the frequency of the zero-phase voltage is seen, it vibrates in the third order. Further, the oscillation of the output PQ of the self-excited AC / DC converter 3 converges, and it can be seen that the operation of the self-excited AC / DC converter 3 and the distortion of the bus voltage of the AC system bus 1 are irrelevant.
[0187]
FIG. 21B shows the same case where a tertiary filter is inserted at the neutral point of the phase adjusting transformer 17 on the way. The distortion of the bus voltage of the AC system bus 1 is rapidly reduced immediately after being turned on, and the zero-phase voltage is also small. On the other hand, the output of the self-excited AC / DC converter 3 is not different from that in the case of no input. From this simulation result, it is clear that the distortion suppression effect of inserting the harmonic filter 50 to the neutral point when the zero-phase harmonics are generated. It has also been confirmed that this does not affect the operation of the self-excited AC / DC converter 3.
[0188]
According to the eighth embodiment, when the self-excited AC / DC converter 3 applied to the DC power transmission system or the DC power supply system is suddenly disconnected from the AC power supply, the bus side of the transformer 17 By controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the neutral point circuit, the harmonics generated in the zero-phase circuit of the AC system bus 1 without affecting the operation of the self-excited AC / DC converter 3. Wave distortion can be suppressed at high speed. Further, since the harmonic filter 50 is not always connected to the circuit, the stress applied to the harmonic filter 50 can be reduced.
[0189]
Next, a ninth embodiment of the present invention will be described. FIG. 22 is a configuration diagram of a circuit breaker circuit control device according to the ninth embodiment. In the ninth embodiment, the eighth embodiment shown in FIG. 19 is a case where the power system to which the AC system bus 1 is connected in the steady state is a non-grounded neutral point. In the steady state, the power system to which the AC system bus 1 is connected is a neutral point direct ground.
[0190]
In FIG. 22, a circuit breaker 52 is installed at the neutral point of the transformer 17 in parallel with the circuit breaker 49 and the harmonic filter 50, and one end thereof is grounded. As in the eighth embodiment, the circuit breaker 49 is turned on by a command from the circuit breaker control circuit 48 in a normally open state. On the other hand, the circuit breaker 52 is turned on in a steady state and is opened by a command signal from the delay circuit 51. The delay circuit 51 receives the closing signal from the circuit breaker control circuit 48, inverts it and delays it for a fixed time, and then gives an open command to the circuit breaker 52.
[0191]
Next, the operation will be described. Since the AC circuit breakers 21 and 21 ′ are normally turned on, the AC system bus 1, the self-excited AC / DC converter 3, the transformer 17, etc. are connected to a power system 23 including a plurality of generators 22. Yes. Since a three-phase sine wave AC voltage is applied from the power source, the harmonic voltage of the AC system bus 1 is small. Since the output of the circuit breaker state monitoring device 24 is “0”, the circuit breaker control circuit 48 does not give a closing command to the circuit breaker 49 and the circuit breaker 49 is in an open state. On the other hand, since the circuit breaker 52 is in the on state, the transformer 17 is operated in a state where the primary side neutral point is directly grounded. The harmonic filter 50 is disconnected from the circuit.
[0192]
Next, the operation when the circuit breaker 21 suddenly becomes three-phase open in the AC system while the self-excited AC / DC converter 3 is operating will be described. When the circuit breaker 21 is in an open state, the self-excited AC / DC converter 3 can suppress the harmonics of the zero phase component of the bus voltage of the AC system bus 1 as in the case of the eighth embodiment. The distortion continues. Since the neutral point is grounded, the harmonic voltage is smaller than that of non-grounded, but the transformer impedance etc. acts as part of the zero-phase impedance, so that a harmonic voltage that cannot be ignored is generated. The generated zero-phase harmonic circulates through a leakage capacitance or the like and attenuates little by little due to the resistance of the circuit, so the duration is long.
[0193]
Therefore, in the ninth embodiment, when the output of the circuit breaker state monitoring device 24 is “1”, a closing instruction is given from the circuit breaker control circuit 48 to the circuit breaker 49. As a result, the harmonic filter 50 is input to the primary neutral point of the transformer 17. In this state, since the neutral point current flows through this circuit when the circuit breaker 52 is turned on, the current does not flow through the harmonic filter 50 and the damping effect cannot be obtained, so that the harmonic is not attenuated. Then, after a certain period of time, the delay circuit 51 operates and the circuit breaker 52 is opened. As a result, the neutral point current flows through the harmonic filter 50, and the vibration is attenuated by the resistance, thereby suppressing the harmonic.
[0194]
According to the ninth embodiment, when the self-excited AC / DC converter 3 applied to the DC power transmission system or the DC power supply system suddenly becomes disconnected from the AC power supply, the bus side of the transformer 17 By controlling the circuit breaker 49 so as to insert the harmonic filter 50 into the neutral point circuit, the harmonic distortion generated in the AC system bus 1 can be accelerated without affecting the operation of the self-excited AC / DC converter 3. Can be suppressed. Further, since the harmonic filter 50 is not always connected to the circuit, the stress applied to the harmonic filter 50 can be reduced.
[0195]
Next, a tenth embodiment of the present invention will be described. FIG. 23 is a configuration diagram of a circuit breaker circuit control device according to the tenth embodiment. The tenth embodiment is applied to a case where the neutral point is not grounded, and is obtained by adding a delay circuit 53 and reset circuits 5 and 4 to the eighth embodiment shown in FIG. It is.
[0196]
In the delay circuit 53, when a closing command is given from the circuit breaker control circuit 48, it is given to the reset circuit 54 as a reset command signal after a predetermined time. When the reset circuit 54 receives a closing command from the circuit breaker control circuit 48, the reset circuit 54 gives the same as a command signal to the circuit breaker 49, but when the reset signal from the delay circuit 53 becomes “1”, Release and release command.
[0197]
Next, the operation will be described. The normal operation is the same as in the eighth embodiment. Next, the operation when the circuit breaker 21 suddenly becomes three-phase open in the AC system while the self-excited AC / DC converter 3 is operating is as follows. When the circuit breaker 21 is in an open state, fluctuations occur, and harmonic distortion occurs in the circuit connected to the AC system bus 1. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the converter, and continue.
[0198]
Therefore, in the tenth embodiment, when the output of the circuit breaker state monitoring device 24 becomes “1”, a closing command is given from the circuit breaker control circuit 48 to the circuit breaker 49 via the reset circuit 54. . As a result, the harmonic filter 50 is input to the primary neutral point of the transformer 17. The voltage generated at the neutral point of the Y-connected circuit is a zero-phase voltage. When the harmonic filter 50 is input to the neutral point, the zero-phase harmonic component is absorbed by the harmonic filter 50, and the harmonic filter 50 is attenuated by the damping effect of the resistance in 50 and the zero-phase harmonic is eliminated. When a certain period of time has passed in this state, the delay circuit 53 operates, the reset command 54 resets the closing command signal to become an opening command signal, and the circuit breaker 49 is opened.
[0199]
As a result, the neutral point circuit returns to the normal state, and the harmonic filter 50 is disconnected. Since the harmonics generated in the zero-phase circuit are due to the circulating current and are not active, once attenuated, they will not be amplified again.
[0200]
FIG. 24 shows a simulation waveform when the harmonic filter 50 is inserted and then opened again after a predetermined time. By inserting the harmonic filter 50, the distortion of the bus voltage of the AC system bus 1 is eliminated, and even if the harmonic filter 50 is opened thereafter, the phenomenon that the distortion recurs does not appear. Further, there is no influence on the operation of the self-excited AC / DC converter 3 by turning on / off the harmonic filter 50.
[0201]
According to the tenth embodiment, when the self-excited AC / DC converter 3 applied to a DC power transmission system or a DC power supply system suddenly becomes disconnected from the AC power supply, Harmonic distortion generated in the AC bus 1 without affecting the operation of the self-excited AC / DC converter 3 by controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the sex point circuit only for a certain period of time. Can be suppressed at high speed. Further, since the time for connecting the harmonic filter 50 to the circuit is minimized, the stress applied to the harmonic filter 50 can be reduced, and the harmonic filter 50 having a small rating can be obtained.
[0202]
Next, an eleventh embodiment of the present invention will be described. FIG. 25 is a configuration diagram of a circuit breaker circuit control device according to the eleventh embodiment. This eleventh embodiment is applied to the case of neutral grounding directly, and is different from the ninth embodiment shown in FIG. 22 in that delay circuits 53 and 55 and reset circuits 54 and 56 are provided. It is added.
[0203]
The output of the circuit breaker control circuit 48 is given as a closing command to the circuit breaker 49 via the reset circuit 54. Further, in the delay circuit 51, when a closing command is given from the circuit breaker control circuit 48, after a predetermined time, it is inverted and an opening command is given to the circuit breaker 52 via the reset circuit 56. The output of the delay circuit 51 is further given as a reset command to the reset circuit 56 via the delay circuit 55. When this is given, the output of the reset circuit 56 is inverted from “open” to “input”. Further, the output of the delay circuit 55 is given as a reset command to the reset circuit 54 via the delay circuit 53, and when this is given, the output of the reset circuit 54 is inverted from "ON" to "OPEN".
[0204]
Next, the operation will be described. The normal operation is the same as in the ninth embodiment. Next, the operation when the circuit breaker 21 suddenly becomes three-phase open in the AC system while the self-excited AC / DC converter 3 is operating will be described. In the circuit connected to the AC system bus 1, harmonic distortion occurs in the circuit connected to the AC system bus 1 when the circuit breaker 21 is opened. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the converter, and continue.
[0205]
Therefore, in the eleventh embodiment shown in FIG. 25, when the output of the circuit breaker state monitoring device 24 becomes “1”, the circuit breaker control circuit 48 sends a closing command to the circuit breaker 49 via the reset circuit 54. Is given. As a result, the harmonic filter 50 is input to the primary neutral point of the transformer 17. At this time, since the circuit breaker 52 connected in parallel with the harmonic filter 50 is turned on, the neutral point is directly grounded, and the neutral point current (zero phase current) is passed to the ground via the circuit breaker 52. Flowing. When a certain period of time elapses from this state, the delay circuit 51 operates, an open command is given to the circuit breaker 52 via the reset circuit 56, the circuit breaker 52 is opened, and the neutral point of the transformer 17 is the harmonic filter 50. It will be in the state grounded only by.
[0206]
As a result, the zero-phase harmonic component is absorbed by the filter, attenuated by the damping effect of the resistance in the filter, and the zero-phase harmonic is eliminated. Further, when a certain time has passed in this state, the delay circuit 55 operates, the reset command 56 resets the release command signal, and the circuit breaker 52 is turned on again. Further, the delay circuit 53 operates, the input command signal is reset by the reset circuit 54, and the circuit breaker 49 is opened. Accordingly, the neutral point circuit returns to the normal state, and the harmonic filter 50 is disconnected. Since the harmonics generated in the zero-phase circuit are due to the circulating current and are not active, once attenuated, they will not be amplified again.
[0207]
According to the eleventh embodiment, when the self-excited AC / DC converter applied to the DC power transmission system or the DC power supply system suddenly becomes disconnected from the AC power supply, Harmonic distortion generated in the AC bus 1 without affecting the operation of the self-excited AC / DC converter 3 by controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the sex point circuit only for a certain period of time. Can be suppressed at high speed. Further, since the time for connecting the harmonic filter 50 to the circuit is minimized, the stress applied to the harmonic filter 50 can be reduced, and the harmonic filter 50 having a small rating can be obtained.
[0208]
Next, a twelfth embodiment of the present invention will be described. FIG. 26 is a configuration diagram of a circuit breaker circuit control device according to the twelfth embodiment. This twelfth embodiment is applied to a case where the neutral point is not grounded. Compared with the eighth embodiment shown in FIG. 19, the circuit breaker state monitoring device 24 is used as a system state monitoring device. Instead, an AC voltage detector 57, a zero-phase voltage detector 58, a harmonic detector 59, a level detector 60, an integrator 61, and a level detector 62 are provided.
[0209]
From the three-phase AC voltage detected by the AC voltage detector 57, the zero-phase voltage detector 58 and the harmonic detector 59 detect the magnitude of the harmonic voltage of the zero-phase component and input it to the level detector 60. When it exceeds a certain value, the output of the level detector 60 becomes “1” and is given to the integrator 61. Further, when the output of the integrator 61 exceeds a certain level, the output of the level detector 62 becomes “1” and is given to the circuit breaker control circuit 48. Other configurations are the same as those of the eighth embodiment shown in FIG.
[0210]
Next, the operation will be described. The normal operation is the same as in the eighth embodiment. Next, the operation in the case where the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source due to the three-phase opening of the circuit breaker 21 during operation will be described. In the circuit connected to the AC system bus 1, a harmonic distortion occurs due to fluctuations caused by being disconnected from the AC power source. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the self-excited AC / DC converter 3 and are continued.
[0211]
Therefore, in the twelfth embodiment, the zero-phase harmonics generated as described above are processed by the AC voltage detector 57, the zero-phase voltage detector 58, and the harmonic detector 59 in the three-phase AC voltage. The voltage is detected and applied to the level detector 60. If the magnitude of the given zero-phase harmonic voltage exceeds a certain level, the level detector 60 outputs “1”. When it is integrated by the integration circuit 61 and its magnitude exceeds a certain level, that is, when the zero-phase harmonic continues, the level detector 62 operates to give the output “1” to the circuit breaker control circuit 48.
[0212]
Thereby, a closing command is given from the circuit breaker control circuit 48 to the circuit breaker 49, and the harmonic filter output 50 is input to the primary side neutral point of the transformer 17. The voltage generated at the neutral point of the Y-connected circuit is a zero-phase voltage. When the harmonic filter 50 is input to the neutral point, the zero-phase harmonic component is absorbed by the harmonic filter 50, and the harmonic filter 50 is attenuated by the damping effect of the resistance in 50 and the zero-phase harmonic is eliminated.
[0213]
According to the twelfth embodiment, when the zero-phase harmonic voltage increases in the AC system to which the self-excited AC / DC converter 3 applied to the DC power transmission system or DC power supply system is connected, the transformer 17 By controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the neutral point circuit on the bus side, the harmonic distortion generated in the AC system bus 1 can be reduced without affecting the operation of the self-excited AC / DC converter 3. It can be suppressed at high speed. Further, since the harmonic filter 50 is not always connected to the circuit, the stress applied to the harmonic filter 50 can be reduced.
[0214]
Next, a thirteenth embodiment of the present invention will be described. FIG. 27 is a configuration diagram of a circuit breaker circuit control device according to the thirteenth embodiment. This thirteenth embodiment is applied to the case of neutral point direct grounding. Compared to the ninth embodiment shown in FIG. 22, the circuit breaker state monitoring device 24 is used as a system state monitoring device. Instead, an alternating current detector 63, a harmonic detector 64, a level detector 60, an integrator 61, and a level detector 62 are provided.
[0215]
The AC current detector 63 and the harmonic detector 64 detect the harmonic component of the current flowing from the primary neutral point of the transformer 2 for the converter to the ground and apply it to the level detector 60, which exceeds a certain value. In this case, the output of the level detector 60 becomes “1” and is given to the integrator 61. Further, when the output of the integrator 61 exceeds a certain level, the output of the level detector 62 becomes “1” and is given to the circuit breaker control circuit 48. Other configurations are the same as those of the ninth embodiment shown in FIG.
[0216]
Next, the operation will be described. The normal operation is the same as in the ninth embodiment. Next, the operation in the case where the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source due to the three-phase opening of the circuit breaker 21 during operation will be described. In the circuit connected to the AC system bus 1, a harmonic distortion occurs due to fluctuations caused by being disconnected from the AC power source. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the self-excited AC / DC converter 3 and are continued. When the neutral point is directly grounded, a zero-phase harmonic current flows from the neutral point to the ground.
[0217]
Therefore, in the thirteenth embodiment, the zero-phase harmonic current is detected by the alternating current detector 63 and the harmonic detector 64 provided at the neutral point of the transformer 2 for the converter, and applied to the level detector 60. . If the magnitude of the given zero-phase harmonic current exceeds a certain level, the level detector 60 outputs “1”. When it is integrated by the integration circuit 61 and its magnitude exceeds a certain level, the level detector 62 operates to give the output “1” to the circuit breaker control circuit 48. Thereby, a closing command is given from the circuit breaker control circuit 48 to the circuit breaker 49, and the harmonic filter output 50 is input to the primary side neutral point of the transformer 17. Further, a signal from the circuit breaker control circuit 48 is given to the circuit breaker 52 as a release command after a predetermined time through the delay circuit 51, and the circuit breaker 52 is opened.
[0218]
As a result, the zero-phase current flows through the harmonic filter 50, the zero-phase harmonic component is absorbed by the filter, attenuates due to the damping effect of the resistance in the filter, and the zero-phase harmonic is eliminated.
[0219]
According to the thirteenth embodiment, when the zero-phase harmonic component increases in the AC system to which the self-excited AC / DC converter 3 applied to the DC power transmission system or DC power supply system is connected, the transformer 17 By controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the neutral-point circuit on the bus side, the harmonic distortion generated in the AC system bus 1 without affecting the operation of the self-excited AC / DC converter 3 Can be suppressed at high speed. Further, since the harmonic filter 50 is not always connected to the circuit, the stress applied to the harmonic filter 50 can be reduced.
[0220]
Next, a fourteenth embodiment of the present invention will be described. FIG. 28 is a configuration diagram of a circuit breaker circuit control device according to the fourteenth embodiment. The fourteenth embodiment is applied to a case where the neutral point is not grounded. In contrast to the tenth embodiment shown in FIG. 23, instead of the delay circuit 53, an AC voltage detector 57, A zero-phase voltage detector 58, a harmonic detector 59, a level detector 65, an integrator 61 ′, and a level detector 62 ′ are provided.
[0221]
From the three-phase AC voltage detected by the AC voltage detector 57, the zero-phase voltage detector 58 and the harmonic detector 59 detect the magnitude of the harmonic voltage of the zero-phase component and input it to the level detector 65. When it is below a certain value Vn, the output of the level detector 65 becomes “1” and is given to the integrator 61 ′. Further, when the output of the integrator 61 ′ exceeds a certain level, that is, when the state where the zero-phase harmonics are small continues, the output of the level detector 62 ′ becomes “1” and the reset command signal is sent to the reset circuit 54. As given. Thereby, when the reset circuit 54 is “1”, that is, in the on state, it is reset and an open command is given to the circuit breaker 49. Other configurations are the same as those of the tenth embodiment shown in FIG.
[0222]
Next, the operation will be described. The normal operation is the same as in the tenth embodiment. Next, the operation in the case where the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source due to the three-phase opening of the circuit breaker 21 during operation will be described. By being disconnected from the AC power supply, fluctuations occur, and harmonic distortion occurs in the circuit connected to the AC system bus 1. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the converter, and continue.
[0223]
Therefore, in the fourteenth embodiment, by the operation of the circuit breaker state monitoring device 24, a closing command is given from the circuit breaker control circuit 48 to the circuit breaker 49, and the harmonic filter 50 is connected to the primary side of the transformer 17. It is thrown into the neutral point. The voltage generated at the neutral point of the Y-connected circuit is a zero-phase voltage, and when the harmonic filter 50 is input to the neutral point, the zero-phase harmonic component is absorbed by the filter. It attenuates due to the damping effect of the resistor and the zero-phase harmonic is eliminated.
[0224]
On the other hand, the AC voltage detector 57, the zero phase voltage detector 58, and the harmonic detector 59 detect the zero phase harmonic component of the bus voltage of the AC system bus 1, but the zero phase harmonic is operated by the above circuit breaker operation. When the wave component is reduced, the detected value becomes smaller than the set level Vn of the level detector 65, and the level detector 65 operates. When this state continues, the output of the integrator 61 ′ increases, and when the predetermined time is exceeded, the level detector 62 ′ operates to give a reset command to the reset circuit 54, thereby opening the circuit breaker 49, The harmonic filter 50 is disconnected, and the neutral point circuit returns to the original state. Since the harmonics generated in the zero-phase circuit are due to the circulating current, once attenuated, they are not amplified again, and the state of low harmonics can be continued.
[0225]
According to the fourteenth embodiment, when the zero-phase harmonic voltage increases in the AC system to which the self-excited AC / DC converter 3 applied to the DC power transmission system or DC power supply system is connected, By controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the neutral point circuit on the bus side, the harmonic distortion generated in the AC system bus 1 can be reduced without affecting the operation of the self-excited AC / DC converter 3. It can be suppressed at high speed. Further, since it is detected that the harmonics are suppressed and the harmonic filter 50 is opened, it is possible to minimize the time during which the harmonic filter 50 is turned on and to reduce the stress applied to the harmonic filter 50. can do.
[0226]
Next, a fifteenth embodiment of the present invention is described. FIG. 29 is a block diagram of a circuit breaker circuit control device according to the fifteenth embodiment. The fifteenth embodiment is applied to a case where the neutral point is not grounded. In contrast to the fourteenth embodiment shown in FIG. 28, the fifteenth embodiment replaces the circuit breaker state monitoring device 24 as a system state monitoring device. In addition, a closing command signal is sent to the circuit breaker control circuit 48 by signals through the AC voltage detector 57, the zero-phase voltage detector 58, the harmonic detector 59, the level detector 60, the integrator 61, and the level detector 62. It is the structure which gives.
[0227]
That is, a closing instruction to the circuit breaker 49 is given by the same circuit as the circuit of the twelfth embodiment shown in FIG. 26, and the circuit breaker 49 is opened by the same circuit as the circuit of the fourteenth embodiment shown in FIG. It is configured to give a command.
[0228]
Next, the operation will be described. The normal operation is the same as in the fourteenth embodiment. Next, the operation in the case where the self-excited AC / DC converter 3 is suddenly disconnected from the AC power source due to the three-phase opening of the circuit breaker 21 during operation will be described. In the circuit connected to the AC system bus 1, harmonic distortion occurs due to fluctuations caused by disconnecting the power source. Among the generated harmonics, the harmonics of the zero phase component cannot be suppressed by the self-excited AC / DC converter 3 and are continued.
[0229]
The level detector 62 operates by detecting the increase of the zero-phase harmonics, and a closing command is given to the circuit breaker 49 via the circuit breaker circuit control device 48 and the reset circuit 54, and the harmonic filter 50 is transformed into the transformer 17. To the neutral point. When the zero-phase harmonics are reduced by turning on the harmonic filter 50, the level detector 62 'operates and a reset command is given to the reset circuit 54, whereby the circuit breaker 49 is opened and the harmonic filter 50 is opened. Is disconnected, and the neutral circuit returns to the original state. Since the harmonics generated in the zero-phase circuit are due to the circulating current, once attenuated, they are not amplified again, and the state of low harmonics can be continued.
[0230]
According to the fifteenth embodiment, when the zero-phase harmonic component increases in the AC system to which the self-excited AC / DC converter 3 applied to the DC power transmission system or the DC power supply system is connected, the transformer 17 By controlling the circuit breaker 49 so that the harmonic filter 50 is inserted into the neutral point circuit on the bus side, the harmonic distortion generated in the AC system bus 1 can be reduced without affecting the operation of the self-excited AC / DC converter 3. It can be suppressed at high speed. Further, since it is detected that the harmonics are suppressed and the harmonic filter 50 is opened, it is possible to minimize the time during which the harmonic filter 50 is turned on and to reduce the stress applied to the harmonic filter 50. can do.
[0231]
【The invention's effect】
As described above, according to the self-excited AC / DC converter control device according to claims 1 to 4 of the present invention, during normal operation, the active power and the reactive power according to the given set values are output, and the self-excited When the AC / DC converter is suddenly disconnected from the AC power supply, while maintaining the AC voltage constant, automatically supplying active power and reactive power with values suitable for the connected load system and phase adjusting equipment, The operation of the self-excited AC / DC converter can be continued stably.
[0232]
In addition, if the capacity of the connected load system or phase adjusting equipment is large and the output of the self-excited AC / DC converter becomes overcurrent, the AC voltage can be reduced to prevent overcurrent and prevent self-excited AC / DC switching. The operation of the converter can be continued to minimize power outages in the load system.
[0233]
According to the self-excited AC / DC converter control device according to claims 5 to 6, during normal operation, the active power and reactive power according to the given set values are output, and the self-excited AC / DC converter is suddenly disconnected from the AC power source. If this happens, the converter will continue to operate stably while automatically supplying active and reactive power with values appropriate for the connected load system and phase-adjusting equipment while keeping the AC voltage constant. be able to.
[0234]
Furthermore, when the capacity of the connected load system and phase adjusting equipment is large and the output of the self-excited AC / DC converter becomes overcurrent, the AC voltage is reduced by a reduction width corresponding to the magnitude and duration of the overcurrent. By operating in such a manner, it is possible to prevent an overcurrent with a minimum necessary AC voltage drop and continue the operation of the converter, thereby minimizing the power failure of the load system.
[0235]
According to the circuit breaker circuit control device according to any one of claims 7 to 10, zero-phase harmonics are generated due to a cause such as disconnecting the AC system to which the self-excited AC / DC converter is connected from the AC power source. If the circuit breaker is operated so that a harmonic filter is temporarily inserted at the neutral point of the circuit when a large distortion occurs in the circuit, the harmonics are suppressed and the device stress due to the harmonics or the transformer By preventing saturation and the like, and preventing the harmonic filter from being connected to the circuit at all times, the stress of the harmonic filter can be reduced and a harmonic filter having a small capacity rating can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram showing an example of an overcurrent detector in the self-excited AC / DC converter control device according to the first embodiment of the present invention.
FIG. 3 is a main circuit single line connection diagram for explaining the principle of overcurrent suppression of a self-excited AC / DC converter by reducing an AC voltage in the first embodiment of the present invention.
FIG. 4 is a simulation waveform diagram showing an overcurrent suppressing effect by applying the self-excited AC / DC converter control device according to the first embodiment of the present invention.
FIG. 5 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a second embodiment of the present invention.
FIG. 6 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a third embodiment of the present invention.
FIG. 7 is a configuration diagram showing an internal configuration of a PWM control circuit in a self-excited AC / DC converter control device according to a third embodiment of the present invention.
FIG. 8 is a waveform diagram illustrating a relationship between a sine wave signal and a carrier wave signal in PWM control in the self-excited AC / DC converter control device according to the third embodiment of the present invention.
FIG. 9 is a simulation waveform diagram showing an overcurrent suppressing effect by applying the self-excited AC / DC converter control device according to the third embodiment of the present invention.
FIG. 10 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a fourth embodiment of the present invention.
FIG. 11 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a fifth embodiment of the present invention.
FIG. 12 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a sixth embodiment of the present invention.
FIG. 13 is a configuration diagram showing an example of an overcurrent detector in a self-excited AC / DC converter control device according to a sixth embodiment of the present invention.
FIG. 14 is a block diagram showing another example of an overcurrent detector in the self-excited AC / DC converter control device according to the sixth embodiment of the present invention.
FIG. 15 is a configuration diagram showing still another example of an overcurrent detector in the self-excited AC / DC converter control device according to the sixth embodiment of the present invention.
FIG. 16 is a configuration diagram of a main part of a self-excited AC / DC converter control device according to a seventh embodiment of the present invention.
FIG. 17 is a configuration diagram of a PWM control circuit in a self-excited AC / DC converter control device according to a seventh embodiment of the present invention.
FIG. 18 is an internal logic diagram of a logic operation circuit in a PWM control circuit in a self-excited AC / DC converter control device according to a seventh embodiment of the present invention.
FIG. 19 is a configuration diagram of a circuit breaker circuit control device according to an eighth embodiment of the present invention.
FIG. 20 is a main circuit connection diagram of a harmonic filter according to an eighth embodiment of the present invention.
FIG. 21 is a simulation waveform diagram showing a zero-phase harmonic suppression effect by applying the circuit breaker circuit control device according to the eighth embodiment of the present invention.
FIG. 22 is a configuration diagram of a circuit breaker circuit control device according to a ninth embodiment of the present invention.
FIG. 23 is a configuration diagram of a circuit breaker circuit control device according to a tenth embodiment of the present invention.
FIG. 24 is a simulation waveform diagram showing a zero-phase harmonic suppression effect by applying the circuit breaker circuit control device according to the tenth embodiment of the present invention.
FIG. 25 is a configuration diagram of a circuit breaker circuit control device according to an eleventh embodiment of the present invention.
FIG. 26 is a configuration diagram of a circuit breaker circuit control device according to a twelfth embodiment of the present invention.
FIG. 27 is a configuration diagram of a circuit breaker circuit control device according to a thirteenth embodiment of the present invention.
FIG. 28 is a configuration diagram of a circuit breaker circuit control device according to a fourteenth embodiment of the present invention.
FIG. 29 is a configuration diagram of a circuit breaker circuit control device according to a fifteenth embodiment of the present invention.
FIG. 30 is a configuration diagram of a conventional self-excited AC / DC converter control device applied to a general DC power transmission system.
[Explanation of symbols]
1, 1A AC system bus
2, 2A Transformer for converter
3, 3A Self-excited AC / DC converter
5 DC transmission lines
6 DC voltage detector
7 AC current detector
8 AC voltage detector
9 Active power detector
10 Reactive power detector
11 DC voltage / active power control circuit
12 Reactive power control circuit
13 AC current control circuit
14 dq axis conversion circuit
15 PWM control circuit
16 Phase detection circuit
24 Circuit breaker status monitoring device
25, 25 'signal holding circuit
26, 26 'primary delay circuit
27, 27 'adder
28, 28 'switch circuit
29, 29 'current control element
30, 30 'adder
31 AC voltage detector
32, 32 'switch circuit
33, 33 'adder
34 Switch circuit
35 Overcurrent detector
36 Voltage control elements
37, 37 'adder
39 Frequency deviation detector
41 Integrator with reset
48 Circuit breaker control circuit
49 Circuit breaker
50 Harmonic filter
51 Delay circuit
52 Circuit breaker
53 Delay circuit
54 Reset circuit
55 Delay circuit
56 Reset circuit
57 AC voltage detector
58 Zero-phase voltage detector
59 Harmonic detector
60 level detector
61, 61 'integrator
62, 62 'level detector
63 AC current detector
64 harmonic detector
65 level detector
351 arithmetic circuit

Claims (10)

In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter,
A dq-axis conversion circuit that converts the AC output current of the self-excited AC / DC converter into two-axis variables of an active power component d-axis and a reactive power component q-axis on orthogonal coordinate axes;
A DC voltage / active power control circuit that calculates a set value of the d-axis that satisfies a predetermined active power set value while maintaining the DC voltage of the DC power transmission system at the set value;
A reactive power control circuit that calculates a set value of the q-axis that satisfies a predetermined reactive power set value;
An alternating current control circuit that calculates a control rate such that each output current of the d-axis and the q-axis from the dq-axis conversion circuit follows a set value of the d-axis and the q-axis;
A phase detection circuit for detecting an AC voltage phase of a bus of the AC power system;
Based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit, the self-excited AC / DC conversion is performed so as to output active power and reactive power according to the set value while maintaining the DC voltage at the set value. A PWM control circuit for controlling the device;
A system state monitoring device that operates when a generator of an AC system to which the self-excited AC / DC converter is connected is disconnected; and
A signal holding circuit that holds the output of the alternating current control circuit at a value of a prior operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit;
A first-order lag circuit that inputs the d-axis and q-axis output currents from the dq-axis conversion circuit and outputs first-order lag d-axis and q-axis output currents;
The control rate correction signal is calculated and output to the PWM control circuit based on the deviation between the d-axis and q-axis output currents and the first-order lag d-axis and q-axis output currents by the operation of the system state monitoring device. Current control element to
When the AC voltage of the AC system rises above its voltage setting value, the PWM control circuit provides a correction signal for correcting the control rate so that the absolute value increases when the absolute value decreases so as to decrease. A voltage control element to output to
An overcurrent detector that reduces the voltage setting value of the voltage control element to a small value when the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for a predetermined time;
A self-excited AC / DC converter control device comprising: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter,
A dq-axis conversion circuit that converts the AC output current of the self-excited AC / DC converter into two-axis variables of an active power component d-axis and a reactive power component q-axis on orthogonal coordinate axes;
A DC voltage / active power control circuit that calculates a set value of the d-axis that satisfies a predetermined active power set value while maintaining the DC voltage of the DC power transmission system at the set value;
A reactive power control circuit that calculates a set value of the q-axis that satisfies a predetermined reactive power set value;
An alternating current control circuit that calculates a control rate such that each of the d-axis and q-axis output currents from the dq-axis conversion circuit follows the setting of the d-axis and the q-axis;
A phase detection circuit for detecting an AC voltage phase of the AC power system;
Based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit, the self-excited AC / DC conversion is performed so as to output active power and reactive power according to the set value while maintaining the DC voltage at the set value. A PWM control circuit for controlling the device;
A system state monitoring device that operates when a generator of an AC system to which the self-excited AC / DC converter is connected is disconnected; and
A signal holding circuit that holds the output of the alternating current control circuit at a value of a prior operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit;
A first-order lag circuit that inputs the d-axis and q-axis output currents from the dq-axis conversion circuit and outputs first-order lag d-axis and q-axis output currents;
The control rate correction signal is calculated and output to the PWM control circuit based on the deviation between the d-axis and q-axis output currents and the first-order lag d-axis and q-axis output currents by the operation of the system state monitoring device. Current control element to
When the AC voltage of the AC system bus rises above its voltage setting value, the PWM signal is used to correct the control rate so that the absolute value increases when the absolute value decreases. A voltage control element to output to the circuit;
When the AC output current of the self-excited AC / DC converter exceeds a predetermined value for a predetermined time or longer, the limit value for the peak value of the sine wave signal used in the pulse width control in the PWM control circuit is set to a smaller value than usual. An overcurrent detector,
A self-excited AC / DC converter control device comprising: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. In the self-excited AC / DC converter control device used to control each self-excited AC / DC converter,
A dq-axis conversion circuit that converts the AC output current of the self-excited AC / DC converter into two-axis variables of an active power component d-axis and a reactive power component q-axis on orthogonal coordinate axes;
A DC voltage / active power control circuit that calculates a set value of the d-axis that satisfies a predetermined active power set value while maintaining the DC voltage of the DC power transmission system at the set value;
A reactive power control circuit that calculates a set value of the q-axis that satisfies a predetermined reactive power set value;
An alternating current control circuit that calculates a control rate such that each output current of the d-axis and the q-axis from the dq-axis conversion circuit follows a set value of the d-axis and the q-axis;
A phase detection circuit for detecting an AC voltage phase of an AC bus of the power supply system;
Based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit, the self-excited AC / DC conversion is performed so as to output active power and reactive power according to the set value while maintaining the DC voltage at the set value. A PWM control circuit for controlling the device;
A system state monitoring device that operates when a generator of an AC system to which the self-excited AC / DC converter is connected is disconnected; and
A signal holding circuit that holds the output of the alternating current control circuit at a value of a prior operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit;
A first-order lag circuit that inputs the d-axis and q-axis output currents from the dq-axis conversion circuit and outputs first-order lag d-axis and q-axis output currents;
The control rate correction signal is calculated and output to the PWM control circuit based on the deviation between the d-axis and q-axis output currents and the first-order lag d-axis and q-axis output currents by the operation of the system state monitoring device. Current control element to
When the AC voltage of the AC system bus rises above its voltage setting value, the PWM signal is used to correct the control rate so that the absolute value increases when the absolute value decreases. A voltage control element to output to the circuit;
When the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for a predetermined time or more, the voltage setting value of the voltage control element is decreased and the sine used for pulse width control in the PWM control circuit. An overcurrent detector that makes the limit value for the peak value of the wave signal smaller than normal,
A self-excited AC / DC converter control device comprising: In order to provide power interchange between a plurality of AC power systems, there is a DC power transmission system in which self-excited AC / DC converters that perform power conversion are installed in the AC power systems, and DC terminals of the self-excited AC / DC converters are connected. used in self-commutated AC-DC converter control device for controlling the own-commutated AC-DC converter,
A dq-axis conversion circuit that converts the AC output current of the self-excited AC / DC converter into two-axis variables of an active power component d-axis and a reactive power component q-axis on orthogonal coordinate axes;
A DC voltage / active power control circuit that calculates a set value of the d-axis that satisfies a predetermined active power set value while maintaining the DC voltage of the DC power transmission system at the set value;
A reactive power control circuit that calculates a set value of the q-axis that satisfies a predetermined reactive power set value;
An alternating current control circuit that calculates a control rate such that each output current of the d-axis and the q-axis from the dq-axis conversion circuit follows a set value of the d-axis and the q-axis;
A phase detection circuit for detecting an AC voltage phase of an AC bus of the power supply system;
Based on the AC voltage phase from the phase detection circuit and the control rate from the AC current control circuit, the self-excited AC / DC conversion is performed so as to output active power and reactive power according to the set value while maintaining the DC voltage at the set value. A PWM control circuit for controlling the device;
A system state monitoring device that operates when a generator of an AC system to which the self-excited AC / DC converter is connected is disconnected; and
A signal holding circuit that holds the output of the alternating current control circuit at a value of a prior operation state by the operation of the system state monitoring device and outputs the value to the PWM control circuit;
A first-order lag circuit that inputs the d-axis and q-axis output currents from the dq-axis conversion circuit and outputs first-order lag d-axis and q-axis output currents;
The control rate correction signal is calculated and output to the PWM control circuit based on the deviation between the d-axis and q-axis output currents and the first-order lag d-axis and q-axis output currents by the operation of the system state monitoring device. Current control element to
When the AC voltage of the AC system bus rises above its voltage setting value, the PWM signal is used to correct the control rate so that the absolute value increases when the absolute value decreases. A voltage control element to output to the circuit;
When the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for more than a predetermined time and the reactive power component advances and is reactive power, the voltage setting value of the AC voltage is switched to a small value when the reactive power is delayed Is an overcurrent detector that makes the limit value for the peak value of the sine wave signal used in the pulse width control in the PWM control circuit smaller than usual,
A self-excited AC / DC converter control device comprising: In the self-excited AC / DC converter control device according to claim 1, claim 3, or claim 4,
The overcurrent detector is configured to reduce the voltage setting value when the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for a certain time or more and the voltage setting value of the AC voltage is set to a small value. A self-excited AC / DC converter control device characterized in that the width is set to a value corresponding to the magnitude and duration of the AC output current. In the self-excited AC / DC converter control device according to claim 2, claim 3, or claim 4,
In the overcurrent detector, the AC output current of the self-excited AC / DC converter continuously exceeds a predetermined value for a predetermined time or more, and a limit value for a peak value of a sine wave signal used for pulse width control in the PWM control circuit is set . When the value is smaller than normal, the reduction range of the limit value with respect to the peak value of the sine wave signal is set to a value according to the magnitude and duration of the overcurrent of the AC output current. Self-excited AC / DC converter controller.    Between the neutral point of the transformer connected to the same alternating current system bus or the nearby alternating current system bus to which the self-excited AC / DC converter according to any one of claims 1 to 6 is connected, and the ground In addition, when the circuit breaker and the harmonic filter are installed in series, the circuit breaker is normally opened, and the AC generator to which the self-excited AC / DC converter is connected is disconnected. A circuit breaker circuit control device comprising a circuit breaker control circuit for introducing a circuit breaker, wherein the harmonic filter suppresses harmonics. The circuit breaker circuit control device according to claim 7,
2. A circuit breaker circuit control device according to claim 1, wherein when a predetermined time has elapsed after the circuit breaker control circuit gives an input command to the circuit breaker, a circuit breaker opening command is issued.   Between the neutral point of the transformer connected to the same alternating current system bus or the nearby alternating current system bus to which the self-excited AC / DC converter according to any one of claims 1 to 6 is connected, and the ground The circuit breaker and the harmonic filter are installed in series, and the circuit breaker is normally opened, and the harmonic component of the zero-phase voltage of the AC bus connected to the self-excited AC / DC converter has a constant value. A circuit breaker circuit control device comprising a circuit breaker control circuit for turning on the circuit breaker when exceeding, and suppressing harmonics with the harmonic filter. In the circuit breaker circuit control device according to claim 7 or 9,
When the magnitude of the harmonics of the zero phase voltage of the AC system bus of the self-excited AC / DC converter is not less than a predetermined value for a certain time or more with the circuit breaker turned on, the circuit breaker should be opened. A circuit breaker circuit control device characterized in that the circuit breaker circuit is provided.

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