JP4443792B2

JP4443792B2 - Independent operation detection system for private power generation facilities

Info

Publication number: JP4443792B2
Application number: JP2001135096A
Authority: JP
Inventors: 有典前仲
Original assignee: CTC Corp
Current assignee: CTC Corp
Priority date: 2001-05-02
Filing date: 2001-05-02
Publication date: 2010-03-31
Anticipated expiration: 2021-05-02
Also published as: JP2002330544A

Description

【０００１】
【発明の属する技術分野】
本発明は電力需要家に設備された自家用発電設備の単独運転検出装置に関するものである。
【０００２】
【従来の技術】
近年、電力を大量に消費する需要家においては、所内の電力消費を節約し、また非常停電等の発生時に所内に電力を供給するために自家用発電機を設置し、電力会社から一定の電力の供給を受けながら、自家用発電機で発生した安価な電力を所内の自家用負荷に供給する自家用発電設備が盛んに設置されつつある。
この自家用発電設備と、電力会社の電力供給側系統は、「系統連系技術用件ガイドライン」に添って安全を維持するための必要な対策が設けられ、自家用発電設備内故障や電力供給側故障等の発生時には各種の保護装置により負荷側の機器類の損失を防止し、早急な故障回復に務めている。
【０００３】
しかし、近年、電力供給側において、新エネルギー等分散型電源から余剰電力を積極的に購入するように法規が改正され、自家用発電設備においても一定の条件のもとで電力供給側への連系に応じて余剰電力の販売が可能となり、逆潮流防止装置を装備する必要がなくなりつつある。
しかしながら、自家用発電機の余剰電力を電力供給側に供給できるように逆潮流が許容された設備において、電力供給側が不健全状態にあるか否か、即ち電力会社の発電所側の遮断器が開路されているか、或いは配電線が断線しているか否かを自家用発電設備側で検出することができず、配電線の故障等により電力供給側の各遮断器が開路した状態で自家用発電設備側の連系遮断器が閉路して自家用発電設備が単独運転すると、電力供給側の故障した配電線に自家用発電機の電圧が印加されて配電線の保守点検、復旧作業等が危険となるという問題があった。
【０００４】
そこで、電力供給側が不健全状態で自家用発電設備側の連系遮断器を正確に開路して各種事故の発生を防止できるようにするために、電力供給側に連系された自家用発電設備側から電力供給側が不健全状態で自家用発電設備が単独運転していることを容易に検出できる装置が要望されている。
【０００５】
【発明が解決しようとする課題】
本発明は上記問題点に鑑みなされたもので、電力供給側に連系された自家用発電設備側から電力供給側が不健全状態で自家用発電設備が単独運転していることを容易に検出でき、しかも発熱を最小限に抑え、小型化できてコストダウンが図れる自家用発電設備の単独運転検出装置を得ることを目的とする。
【０００６】
【課題を解決するための手段】
本発明の請求項１に係る自家用発電設備の単独運転検出装置は、系統電力会社側の配電線と自家用発電機との間に設けられた分岐線に直列に設けられた第１及び第２の電流検出器と、分岐線における第１及び第２の電流検出器の間の線路に正逆並列接続された一対の半導体素子を介して接続された検出用負荷コンデンサと、一対の半導体素子と検出用負荷コンデンサの接続点にスイッチを介して接続された電荷放電用抵抗と、配電線側の第１の電流検出器に流れる電流のピーク値を検出する第１の電流ピーク値検出器と、自家用発電機側の第２の電流検出器に流れる電流のピーク値を検出する第２の電流ピーク値検出器と、分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをＯＮするよう制御するスイッチ制御回路と、検出用負荷コンデンサに電流が流れている時における第１電流ピーク値検出器が検出した少なくとも１サイクルの電流のピーク値又は電流のピーク値に基づく平均値或いは実効値が所定の値と略同じか、或いは第２電流ピーク値検出器が検出した少なくとも１サイクルの電流のピーク値又は電流のピーク値に基づく平均値或いは実効値が所定の値より大きいときは自家用発電設備が単独運転の場合と判定する単独運転判定部とを備えて構成されている。
【０００７】
本発明の請求項２に係る自家用発電設備の単独運転検出装置は、系統電力会社側の配電線と自家用発電機との間に設けられた分岐線に直列に設けられた第１及び第２の電流検出器と、分岐線における第１及び第２の電流検出器の間の線路に正逆並列接続された一対の半導体素子を介して接続された検出用負荷コンデンサと、一対の半導体素子と検出用負荷コンデンサの接続点にスイッチを介して接続された電荷放電用抵抗と、配電線側の第１の電流検出器に流れる電流の積分値を検出する第１の電流積分値検出器と、自家用発電機側の第２の電流検出器に流れる電流の積分値を検出する第２の電流積分値検出器と、分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをオンするよう制御するスイッチ制御回路と、検出用負荷コンデンサに電流が流れている時における第１電流積分値検出器が検出した少なくとも１サイクルの電流の積分値が所定の値と略同じか、或いは第２電流積分値検出器が検出した少なくとも１サイクルの電流の積分値が所定の値より大きいときは自家用発電設備が単独運転の場合と判定する単独運転判定部とを備えて構成されている。
【００１０】
【発明の実施の形態】
実施の形態１
図１は本発明の実施形態１の自家用発電設備の単独運転検出装置の構成を示す単線結線図、図２は同単独運転検出装置の原理的な構成を示す単線結線図、図３は同単独運転検出装置の分岐線から検出用インピーダンス負荷に流れる電流の模式化した波形図、図４は同自家用発電設備の単独運転検出装置の検出用負荷コンデンサに生じる残留電荷を説明するための波形図である。
図において、１は電力を供給する系統電力会社、２は系統電力会社１から配電線３を介して電力が供給される自家用発電設備、４は系統電力会社１と配電線３との間に設けられた遮断器である。配電線３には複数の一般負荷５が接続されている。これらの一般負荷５は内部に遮断器や断路器等が接続されて地絡事故等が発生したときに各負荷を配電線３より分離して危険を防止する。
６は自家用発電設備２に設けられ、配電線３の分岐点Ｐより分岐された分岐線、７は分岐線６の分岐点Ｐ側に接続された自家用連系遮断器、８は分岐線６の端末側に接続された自家用発電機、９は自家用発電機８に分岐線６を介して接続された自家用負荷である。
【００１１】
１０、１１は分岐線６に直列に設けられた第１及び第２電流検出器（ＣＴ１、ＣＴ２）である。１２は配電線側（以下、「系統側」という）の第１電流検出器１０に流れる電流のピーク値を検出する第１電流ピーク値検出器、１３は自家用発電機８側（以下、「発電機側」という）の第２電流検出器１１に流れる電流のピーク値を検出する第２電流ピーク値検出器、１４は系統側の第１電流検出器１０に流れる電流の積分値を検出する第１電流積分値検出器、１５は発電機側の第２電流検出器１１に流れる電流の積分値を検出する第２電流積分値検出器、１６は第１及び第２電流ピーク値検出器１２、１３と第１及び第２電流積分値検出器１４、１５に接続され、これらの検出値から自家用発電設備２の単独運転を検出する単独運転判定部である。
【００１２】
２０、２１は分岐線６における第１及び第２電流検出器１０、１１の間の線路ａに正逆並列接続された一対の半導体素子であるＩＧＢＴ、２２は一端が一対のＩＧＢＴ２０、２１に接続され、他端が接地された検出用負荷コンデンサ、２３は一端が検出用負荷コンデンサ２２に接続され、他端が接地された電荷放電用抵抗、２４は一端が検出用負荷コンデンサ２２に接続され、他端が電荷放電用抵抗２３に接続されたスイッチである。
２５は分岐線６に流れる電流のゼロクロス点を検出するゼロクロス点検出回路、２６はゼロクロス点検出回路２８が検出したゼロクロス点に基づいて一対のＩＧＢＴ２０、２１をオン・オフさせると共にスイッチ２４をオン・オフさせるスイッチ駆動回路である。
【００１３】
まず、本発明の実施の形態１の自家用発電設備の単独運転検出装置により自家用発電設備２の単独運転を検出できる原理の大略を図２に基づいて説明する。なお、図２において、図１と実質的に同一の構成は同一符号を付して説明を省略する。
例えば、自家用発電設備２内の自家用負荷９が必要とする電力を自家用発電機８を駆動しながら供給する。そして、自家用負荷９の電力が自家用発電機８の出力以上に必要となったら、不足する電力が系統電力会社１から自家用連系遮断器７を経由して自家用負荷９へ供給される。
又、自家用負荷９の負荷容量が減少して自家用発電機８の出力に余剰電力が発生したら、この余剰電力は自動的に自家用連系遮断器７より電力供給側である系統電力会社１側へ逆潮させて余剰電力を系統電力会社１へ販売するものである。
【００１４】
ところで、自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と系統電力会社１側と連系中に不健全な状態となり自家用発電設備２が単独運転している場合では、図２に示すように系統電力会社１側の配電線３と自家用発電機８との間に設けられた分岐線６に検出用負荷コンデンサ２２を瞬間的に投入すると、その分岐線６の系統側と発電機側とに流れる電流のピーク値がそれぞれ違うことにより、それに基づき連系されて正常な場合か単独運転の場合かを判定するようにしたものである。
ここで、系統電力会社１側と連系中に不健全な状態となり自家用発電設備２が単独運転している場合とは系統電力会社１側に故障が発生して連系遮断器４が開路されているか、或いは配電線３が断線している場合をいう。
【００１５】
自家用発電設備が系統電力会社側と連系されて健全な正常な場合に、分岐線６に流れている電流のゼロクロス点でスイッチＳをオンして検出用負荷コンデンサ２２を瞬間的に投入した時に、分岐線６の系統側と発電機側とに流れる電流を第１及び第２電流検出器１０、１１で検出すると、その電流波形は図３の（ａ）の破線で示すように、発電機側の第２電流検出器１１（ＣＴ２）が検出する電流のピーク値は少ししか変化しないが、系統側の第１電流検出器１０（ＣＴ１）が検出する電流のピーク値は大きく変化することが分かる。
これは自家用発電機８の発電電流が発電機側から系統側に流れている場合に検出用負荷コンデンサ２２を瞬間的に投入した時に、発電機側からの電流ｉｇの他に系統側からの電流ｉｋが検出用負荷コンデンサ２２に流れる込み、しかもｉｋはｉｇに比べて非常に大きいために第１電流検出器１０（ＣＴ１）が検出する電流が減少することによるためと考えられるからである。
【００１６】
次に、自家用発電設備が系統電力会社側と連系中に不健全な状態となって自家用発電設備が単独運転している場合に、分岐線６に流れている電流のゼロクロス点でスイッチ１２をオンして検出用負荷コンデンサ２２を瞬間的に投入した時に、分岐線６の系統側と発電機側とに流れる電流を第１及び第２の電流検出器１０と１１とで検出すると、その電流波形は図３の（ｂ）の破線で示すように、系統側の第１の電流検出器１０（ＣＴ１）が検出する電流のピーク値は少ししか変化しないが、発電機側の第２の電流検出器１１（ＣＴ２）が検出する電流のピーク値は大きく変化することが分かっている。
【００１７】
これは自家用発電機８の発電電流が発電機側から系統側に流れている場合に検出用負荷コンデンサ２２を瞬間的に投入した時に、今まで系統側からの電流ｉｋは流れずゼロでそのままであるが、発電機側からの電流ｉｇは検出用負荷コンデンサ２２が投入された分だけ余計に流れ込むために第２電流検出器１１（ＣＴ２）が検出する電流が増大することによるためと考えられるからである。
従って、第１電流検出器１０又は第２電流検出器１１で検出した電流のピーク値の変化を見ることにより、自家用発電設備が系統電力会社側と連系されて健全な正常な場合と系統電力会社側と連系中に不健全な状態で自家用発電設備が単独運転している場合とを判定することができる。
【００１８】
次に、本発明の実施の形態１の自家用発電設備の単独運転検出装置の動作について説明する。
まず、一対のＩＧＢＴ２０、２１がオフしている状態のままでは、分岐線６に流れている電流の一部が検出用負荷コンデンサ２２に流れることはないから、検出用負荷コンデンサ２２がないのと同じ状態となり、分岐線６に流れる電流を第１及び第２の電流検出器１０と１１で検出しても、その検出値は同じとなる。これは系統連系中の正常時や単独運転の異常時でも同じである。
【００１９】
次に、分岐線６に流れている電流の１サイクルの間に正の半サイクルが始まるゼロクロス点から正の半サイクルが終わるまでの間はＩＧＢＴ２０をオンし、ＩＧＢＴ２１をオフし、次の負の半サイクルが始まるゼロクロス点から負の半サイクルが終わるまでの間はＩＧＢＴ２０をオフし、ＩＧＢＴ２１をオンする。
そうすると、正の半サイクルの間は検出用負荷コンデンサ２２に正の電流が流れ、次の負の半サイクルの間は検出用負荷コンデンサ２２に負の電流が流れる。
このように、検出用負荷コンデンサ２２に正と負の電流が流れる時における分岐線６に流れる電流の変化を第１電流検出器１０又は第２電流検出器１１で検出して単独運転を検知する。
【００２０】
しかし、検出用負荷コンデンサ２２に正と負の電流を流した場合、正の半サイクルの電流と負の半サイクルの電流が全く等しいときには検出用負荷コンデンサ２２に残留電荷が残ることはないが、正確には正の半サイクルの電流と負の半サイクルの電流が全く等しいということはなく、いずれかの電流分が多いのが通例であるため、検出用負荷コンデンサ２２に残留電荷が残ることになる。
従って、数サイクルにわたって検出用負荷コンデンサ２２に正と負の電流を流していくと、次第に検出用負荷コンデンサ２２に残留電荷が溜まっていき、検出用負荷コンデンサ２２に電流が流れなくなる事態が生じる。
そこで、数サイクルにわたって検出用負荷コンデンサ２２に正と負の電流を流した後に、検出用負荷コンデンサ２２に溜まった残留電荷を除去する必要が生じる。
このため、例えば１秒間のうち、初めの数サイクルは検出用負荷コンデンサ２２に正と負の電流を流し、次の数サイクルは検出用負荷コンデンサ２２に溜まった残留電荷を除去し、これらを１秒間に３〜５回の設定回数り返し、設定した回数を連続して検知した場合に単独運転と判定して異常信号を出す。
【００２１】
以上の動作を図１に基づいて詳細に説明する。
スイッチ駆動回路２６はゼロクロス点検出回路２５からのゼロクロス点検出信号を受けている。
そこで、スイッチ駆動回路２６は例えば１秒間のうち、分岐線６に流れている電流の１サイクルの間に正の半サイクルが始まるゼロクロス点から正の半サイクルが終わるまでの間はＩＧＢＴ２０をオンし、ＩＧＢＴ２１をオフし、次の負の半サイクルが始まるゼロクロス点から負の半サイクルが終わるまでの間はＩＧＢＴ２０をオフし、ＩＧＢＴ２１をオンする。
そうすると、正の半サイクルの間は検出用負荷コンデンサ２２に正の電流が流れ、次の負の半サイクルの間は検出用負荷コンデンサ２２に負の電流が流れる。
そして、この時点における第１及び第２の電流検出器１０、１１が検出した電流から第１及び第２の電流ピーク値検出器１２、１３が検出した電流ピーク値と第１及び第２の電流積分値相検出器１４、１５が検出した電流の積分値は単独運転判定部１６に入力されている。
【００２２】
単独運転判定部１６では、１サイクルの間に検出用負荷コンデンサ２２に電流が流れている時における第１の電流ピーク値検出器１２が検出した電流の正又は負の半サイクルのピーク値と検出用負荷コンデンサ２２に電流が流れていない時における第１の電流ピーク値検出器１２が検出した電流の正又は負の半サイクルのピーク値とを比較し、検出用負荷コンデンサ２２に電流が流れている時における第１の電流ピーク値検出器１２が検出した電流の正又は負の半サイクルのピーク値が検出用負荷コンデンサ２２に電流が流れていない時における第１の電流ピーク値検出器１２が検出した電流の正又は負の半サイクルのピーク値より減少している状態で、両ピーク値の差Ａ１が所定の値Ａ１ref より大きいときは自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と判定することができ、両ピーク値の差Ａ１が所定の値Ａ１ref より小さいときは自家用発電設備２が系統電力会社１側と連系中に不健全な異常な状態となって単独運転をしている場合と判定することができる。
【００２３】
また、１サイクルの間に検出用負荷コンデンサ２２に電流が流れている時における第２の電流ピーク値検出器１３が検出した電流の正又は負の半サイクルのピーク値と検出用負荷コンデンサ２２に電流が流れていない時における第２の電流ピーク値検出器１３が検出した電流の正又は負の半サイクルのピーク値とを比較し、検出用負荷コンデンサ２２に電流が流れている時における第２の電流ピーク値検出器１３が検出した電流の正又は負の半サイクルのピーク値が検出用負荷コンデンサ２２に電流が流れていない時における第２の電流ピーク値検出器１３が検出した電流の正又は負の半サイクルのピーク値より増大している状態で、両ピーク値の差Ａ２が所定の値Ａ２ref より大きいときは自家用発電設備２が系統電力会社１側と連系中に不健全な異常な状態となって単独運転をしている場合と判定することができ、両ピーク値の差Ａ２が所定の値Ａ２ref より小さいときは自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と判定することができる。
なお、検出用負荷コンデンサ２２に電流が流れていない時における第１の電流ピーク値検出器１２と第２の電流ピーク値検出器１３が検出した電流の正又は負の半サイクルのピーク値を単独運転判定部１６に所定の基準値として記憶させておいてもよい。
【００２４】
また、単独運転判定部１６では、１サイクルの間に検出用負荷コンデンサ２２に電流が流れている時における第１の電流積分値検出器１４が検出した電流の正又は負の半サイクルの電流の積分値と検出用負荷コンデンサ２２に電流が流れていない時における第１の電流積分値検出器１４が検出した電流の正又は負の半サイクルの積分値とを比較し、検出用負荷コンデンサ２２に電流が流れている時における第１の電流積分値検出器１４が検出した電流の正又は負の半サイクルの積分値が検出用負荷コンデンサ２２に電流が流れていない時における第１の電流積分値検出器１４が検出した電流の正又は負の半サイクルの積分値より減少している状態で、両積分値の差Ａ３が所定の値Ａ３ref より大きいときは自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と判定することができ、両積分値の差Ａ３が所定の値Ａ３ref より小さいときは自家用発電設備２が系統電力会社１側と連系中に不健全な異常な状態となって単独運転をしている場合と判定することができる。
【００２５】
また、１サイクルの間に検出用負荷コンデンサ２２に電流が流れている時における第２の電流積分値検出器１５が検出した電流の正又は負の半サイクルの積分値と検出用負荷コンデンサ２２に電流が流れていない時における第２の電流積分値検出器１５が検出した電流の正又は負の半サイクルの積分値とを比較し、検出用負荷コンデンサ２２に電流が流れている時における第２の電流積分値検出器１５が検出した電流の正又は負の半サイクルの積分値が検出用負荷コンデンサ２２に電流が流れていない時における第２の電流積分値検出器１５が検出した電流の正又は負の半サイクルの積分値より増大している状態で、両積分値の差Ａ４が所定の値Ａ４ref より大きいときは自家用発電設備２が系統電力会社１側と連系中に不健全な異常な状態となって単独運転をしている場合と判定することができ、両積分値の差Ａ４が所定の値Ａ４ref より小さいときは自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と判定することができる。
なお、検出用負荷コンデンサ２２に電流が流れていない時における第１の電流積分値検出器１１４と第２の電流積分値検出器１５が検出した電流の正又は負の半サイクルの積分値を単独運転判定部１６に予め所定の基準値として記憶させておいてもよい。
【００２６】
そして、この実施の形態１の単独運転判定部１６は、第１電流ピーク値検出器１２が検出した電流のピーク値による判定又は第２電流ピーク値検出器１３が検出した電流のピーク値による判定だけでなく、第１及び第２の電流ピーク値検出器１２が検出した電流のピーク値による判定が同じときに、或いは第１電流積分値検出器１４が検出した電流の積分値による判定又は第２電流積分値検出器１５が検出した電流の積分値による判定だけでなく、第１及び第２の電流積分値検出器１５が検出した電流の積分値による判定が同じときに、更にまた第１及び第２の電流ピーク値検出器１２、１３が検出した電流のピーク値による判定と第１及び第２電流積分値検出器１４、１５が検出した電流の積分値による判定とが同じときに、それぞれ自家用発電設備２が系統電力会社１側と連系されて健全な正常な場合と、自家用発電設備２が系統電力会社１側と連系中に不健全な異常な状態で自家用発電設備２が単独運転している場合とに分けて判定する。
【００２７】
それは、このような２つ又は３つの観点から判断した方がより正確に判定できるからである。
従って、このように自家用発電設備２が系統電力会社１側と連系中に不健全な状態で自家用発電設備２が単独運転していると判定した場合は、直ちに自家用発電設備２を系統電力会社１側から分離させ、自家用発電設備２側の機器類の損傷、或いは系統電力会社１側の配電線３の保守点検時の事故等の各種の事故の発生を防止することができる。
【００２８】
これによって、自家用発電機８は連続運転しながら設備内の自家用負荷９に電力を供給でき、故障により系統側遮断器４やその他の各遮断器が開路されて無負荷状態の電線路３に自家用発電機８等により電力が送電されることなく、安全に故障点検、復旧作業ができる。
また、配電線３の故障復旧後に直ちに系統電力会社１側の系統側遮断器４を閉路しても、自家用連系遮断器７が開路されていれば自家用発電設備２側の機器類が損傷することなく、自家用発電機８は電圧、周波数、位相等を同期検定器等で系統電力会社１側と正確に同期させた後で自家用連系遮断器７を閉路し、連系させながら自家用発電設備２を系統電力会社１側と系統連系させて通常状態に復帰
【００２９】
また、上述の如く、理論的には検出用負荷コンデンサ２２に正と負の電流を流した場合、正の半サイクルの電流と負の半サイクルの電流が全く等しいときには検出用負荷コンデンサ２２に残留電荷が残ることはないが、正確には正の半サイクルの電流と負の半サイクルの電流が全く等しいということはなく、いずれかの電流分が多いのが通例であるため、検出用負荷コンデンサ２２に残留電荷が残ることになる。
【００３０】
そこで、例えば１秒間のうち、初めは検出用負荷コンデンサ２２に電流を流すために、スイッチ駆動回路２６は分岐線６に流れている電流の１サイクルの間に正の半サイクルが始まるゼロクロス点から正の半サイクルが終わるまでの間はＩＧＢＴ２０をオンし、ＩＧＢＴ２１をオフし、次の負の半サイクルが始まるゼロクロス点から負の半サイクルが終わるまでの間はＩＧＢＴ２０をオフし、ＩＧＢＴ２１をオンすることを数サイクル繰り返す。このときはスイッチ駆動回路２６はスイッチ２４をオフしたままである。
【００３１】
しかる後に、今度はスイッチ駆動回路２６は数サイクルの間はＩＧＢＴ２０とＩＧＢＴ２１を共にオフし、スイッチ２４をオンさせる。
そうすると、検出用負荷コンデンサ２２に溜まった残留電荷は電荷放電用抵抗２３で放電されることにより、検出用負荷コンデンサ２２に溜まった残留電荷は除去されることとなる。そこで、これらを１秒間に３〜５回の設定回数り返し、設定した回数を連続して検知した場合に単独運転と判定して異常信号を出す。
なお、検出用負荷コンデンサ２２にはゼロクロス点を基準に電流が流されるので、サージ電流やアークが生じず、検出用負荷コンデンサ２２が破壊されることはない。
また、検出用負荷コンデンサ２２が消費する電力は検出用負荷抵抗に比べて大幅に少なくて済み、発熱も少ないために検出用負荷コンデンサ２２は検出用負荷抵抗に比べて小さいもので済み、装置全体の小型化を図ることもできる。
【００３２】
なお、上記実施の形態１では、単独運転判定部１６が第１電流ピーク値検出器１２が検出した電流のピーク値により判定又は第２電流ピーク値検出器１３が検出した電流のピーク値により判定するようにしているが、かかる電流のピーク値に基づいて平均値又は実効値を演算して求め、平均値又は実効値により判定することができることはいうまでもない。
【００３３】
また、単独運転判定部１６が第１の電流積分値検出器１４、１５が検出した電流の積分値により判定又は第２の電流積分値検出器１５が検出した電流の積分値により判定するようにしたのは、第１電流ピーク値検出器１２が検出した電流のピーク値により判定又は第２電流ピーク値検出器１３が検出した電流のピーク値により判定するのに比べて、電流の積分値であるため、誤動作が少ないことによるものである。
【００３４】
【発明の効果】
本発明の請求項１によれば、系統電力会社側の配電線と自家用発電機との間に設けられた分岐線に直列に設けられた第１及び第２の電流検出器と、分岐線における第１及び第２の電流検出器の間の線路に正逆並列接続された一対の半導体素子を介して接続された検出用負荷コンデンサと、一対の半導体素子と検出用負荷コンデンサの接続点にスイッチを介して接続された電荷放電用抵抗と、配電線側の第１の電流検出器に流れる電流のピーク値を検出する第１の電流ピーク値検出器と、自家用発電機側の第２の電流検出器に流れる電流のピーク値を検出する第２の電流ピーク値検出器と、分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをＯＮするよう制御するスイッチ制御回路とを備え、単独運転判定部が検出用負荷コンデンサに電流が流れている時における第１電流ピーク値検出器が検出した少なくとも１サイクルの電流のピーク値又は電流のピーク値に基づく平均値或いは実効値が所定の値と略同じか、或いは第２電流ピーク値検出器が検出した少なくとも１サイクルの電流のピーク値又は電流のピーク値に基づく平均値或いは実効値が所定の値より大きいときは自家用発電設備が単独運転の場合と判定することができるので、自家用発電設備が単独運転していると判定した場合は直ちに自家用発電設備を系統電力会社側から分離させ、自家用発電設備側の機器類の損傷、或いは系統電力会社側の配電線の保守点検時の事故等の各種の事故の発生を防止できるという効果を有する。
また、スイッチを閉成から開成しても検出用負荷コンデンサに電荷がない状態で開成されるためにアークが生じず、検出用負荷コンデンサが破壊されることはなく、検出用負荷コンデンサが消費する電力は検出用負荷抵抗に比べて大幅に少なくて済み、発熱も少ないために検出用負荷コンデンサは小さいもので済み、装置全体の小型化を図ることもできるという効果がある。
【００３５】
また、スイッチ制御回路は分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをオンするよう制御するので、検出用負荷コンデンサにはゼロクロス点を基準に電流が流されることとなり、サージ電流やアークが生じず、検出用負荷コンデンサが破壊されることはなく、検出用負荷コンデンサに溜まった残留電荷は残留電荷放電用抵抗によって放電されるため、残留電荷の悪影響を受けることはなくなり、検出用負荷コンデンサが消費する電力は検出用負荷抵抗に比べて大幅に少なくて済み、発熱も少ないために検出用負荷コンデンサは小さいもので済み、装置全体の小型化を図ることもできるという効果がある。
【００３６】
本発明の請求項２によれば、系統電力会社側の配電線と自家用発電機との間に設けられた分岐線に直列に設けられた第１及び第２の電流検出器と、分岐線における第１及び第２の電流検出器の間の線路に正逆並列接続された一対の半導体素子を介して接続された検出用負荷コンデンサと、一対の半導体素子と検出用負荷コンデンサの接続点にスイッチを介して接続された電荷放電用抵抗と、配電線側の第１の電流検出器に流れる電流の積分値を検出する第１の電流積分値検出器と、自家用発電機側の第２の電流検出器に流れる電流の積分値を検出する第２の電流積分値検出器と、分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをオンするよう制御するスイッチ制御回路とを備え、単独運転判定部が検出用負荷コンデンサに電流が流れている時における第１電流積分値検出器が検出した少なくとも１サイクルの電流の積分値が所定の値と略同じか、或いは第２電流積分値検出器が検出した少なくとも１サイクルの電流の積分値が所定の値より大きいときは自家用発電設備が単独運転の場合と判定することができるので、自家用発電設備が単独運転していると判定した場合は直ちに自家用発電設備を系統電力会社側から分離させ、自家用発電設備側の機器類の損傷、或いは系統電力会社側の配電線の保守点検時の事故等の各種の事故の発生を防止できるという効果を有する。
【００３７】
また、スイッチ制御回路は分岐線に流れる電流の１秒間のサイクルのうち、数サイクルの間は一対の半導体素子をゼロクロス点毎に交互にオン・オフさせ、その後の数サイクルの間は一対の半導体素子をオフすると共にスイッチをオンするよう制御するので、検出用負荷コンデンサにはゼロクロス点を基準に電流が流されることとなり、サージ電流やアークが生じず、検出用負荷コンデンサが破壊されることはなく、検出用負荷コンデンサに溜まった残留電荷は残留電荷放電用抵抗によって放電されるため、残留電荷の悪影響を受けることはなくなり、検出用負荷コンデンサが消費する電力は検出用負荷抵抗に比べて大幅に少なくて済み、発熱も少ないために検出用負荷コンデンサは小さいもので済み、装置全体の小型化を図ることもできるという効果がある。
【図面の簡単な説明】
【図１】本発明の実施形態１の自家用発電設備の単独運転検出装置の構成を示す単線結線図である。
【図２】同単独運転検出装置の原理的構成を示す単線結線図である。
【図３】同単独運転検出装置の分岐線から検出用負荷コンデンサに流れる電流の模式化した波形図である。
【図４】同自家用発電設備の単独運転検出装置の検出用負荷コンデンサに生じる残留電荷を説明するための波形図である。
【符号の説明】
１系統電力会社
２自家用発電設備
３配電線
６分岐線
８自家用発電機
９自家用負荷
１０第１電流検出器（ＣＴ１）
１１第２電流検出器（ＣＴ２）
１２第１電流ピーク値検出器
１３第２電流ピーク値検出器
１４第１電流積分値検出器
１５第２電流積分値検出器
１６単独運転判定部
２０ＩＧＢＴ（半導体素子）
２１ＩＧＢＴ（半導体素子）
２２検出用負荷コンデンサ
２３電荷放電用抵抗
２５ゼロクロス点検出回路
２６スイッチ駆動回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an independent operation detection device for a private power generation facility installed in a power consumer.
[0002]
[Prior art]
In recent years, consumers who consume a large amount of power have installed a private generator to save power consumption in the facility and supply power to the facility when an emergency power failure occurs. While receiving supply, private power generation facilities that supply inexpensive electric power generated by private power generators to private loads in the office are being actively installed.
This private power generation facility and the power supply system of the power company are provided with necessary measures to maintain safety in accordance with the “Guidelines for grid interconnection technology”. In the event of an occurrence, etc., various protective devices prevent loss of equipment on the load side, and work to recover quickly.
[0003]
However, in recent years, laws and regulations have been revised on the power supply side to actively purchase surplus power from distributed power sources such as new energy, and private power generation facilities are also connected to the power supply side under certain conditions. As a result, surplus power can be sold, and it is no longer necessary to equip a reverse power flow prevention device.
However, in a facility where reverse power flow is allowed so that surplus power of the private generator can be supplied to the power supply side, whether or not the power supply side is in an unhealthy state, that is, the breaker on the power station side of the power company is opened. It is impossible to detect whether the distribution line is disconnected or whether the distribution line is disconnected, and the private generation facility side with each circuit breaker opened due to a breakdown of the distribution line, etc. If the interconnection circuit breaker is closed and the private power generation facility is operated alone, the voltage of the private generator is applied to the broken distribution line on the power supply side, which makes maintenance and restoration work on the distribution line dangerous. there were.
[0004]
Therefore, in order to prevent the occurrence of various accidents by accurately opening the interconnection breaker on the private power generation facility side when the power supply side is in an unhealthy state, from the private power generation facility side connected to the power supply side There is a demand for an apparatus that can easily detect that the power generation side is in an unhealthy state and the private power generation facility is operating alone.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and can easily detect that the power generation side is in an unhealthy state and the private power generation facility is operating independently from the power generation side connected to the power supply side. An object of the present invention is to provide an independent operation detection device for a private power generation facility that can minimize heat generation, reduce the size, and reduce costs.
[0006]
[Means for Solving the Problems]
According to claim 1 of the present invention, an independent operation detection device for a private power generation facility includes a first and a second provided in series on a branch line provided between a distribution line on a grid power company side and a private generator. A current detector, a detection load capacitor connected via a pair of semiconductor elements connected in forward and reverse parallel to a line between the first and second current detectors in the branch line, and a pair of semiconductor elements and detection A charge discharging resistor connected to the connection point of the load capacitor via a switch; A first current peak value detector that detects the peak value of the current flowing through the first current detector on the distribution line side and a first peak value of the current that flows through the second current detector on the private generator side. Two current peak value detectors; Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at each zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. Switch control circuit that controls to turn on, and when current is flowing through the load capacitor for detection The peak value of the current of at least one cycle detected by the first current peak value detector, or an average value or effective value based on the peak value of the current is substantially the same as a predetermined value, or detected by the second current peak value detector The average value or the effective value based on the peak value of the current of at least one cycle or the peak value of the current is When it is larger than the predetermined value, it is configured to include a single operation determination unit that determines that the private power generation facility is in a single operation.
[0007]
According to claim 2 of the present invention, an independent operation detection device for a private power generation facility includes a first and a second provided in series on a branch line provided between a distribution line on a grid power company side and a private generator. A current detector, a detection load capacitor connected via a pair of semiconductor elements connected in forward and reverse parallel to a line between the first and second current detectors in the branch line, and a pair of semiconductor elements and detection A charge discharging resistor connected to the connection point of the load capacitor via a switch; A first current integrated value detector that detects an integrated value of the current flowing through the first current detector on the distribution line side, and a first current detector that detects an integrated value of the current flowing through the second current detector on the private generator side. Two current integral detectors; Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at each zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. Switch control circuit that controls to turn on, and when current is flowing through the load capacitor for detection The integrated value of the current of at least one cycle detected by the first current integrated value detector is substantially the same as the predetermined value, or the integrated value of the current of at least one cycle detected by the second current integrated value detector is When it is larger than the predetermined value, it is configured to include a single operation determination unit that determines that the private power generation facility is in a single operation.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
FIG. 1 is a single-line connection diagram showing the configuration of an isolated operation detection device for private power generation equipment according to Embodiment 1 of the present invention, FIG. 2 is a single-line connection diagram showing the basic configuration of the isolated operation detection device, and FIG. FIG. 4 is a waveform diagram for explaining the residual charge generated in the detection load capacitor of the independent operation detection device of the private power generation facility. FIG. 4 is a waveform diagram schematically showing the current flowing from the branch line of the operation detection device to the detection impedance load. is there.
In the figure, 1 is a grid power company that supplies power, 2 is a private power generation facility to which power is supplied from the grid power company 1 via a distribution line 3, and 4 is provided between the grid power company 1 and the distribution line 3 Circuit breaker. A plurality of general loads 5 are connected to the distribution line 3. These general loads 5 are connected to a circuit breaker, a disconnector, or the like, and when a ground fault or the like occurs, each load is separated from the distribution line 3 to prevent danger.
Reference numeral 6 denotes a private power generation facility 2, a branch line branched from a branch point P of the distribution line 3, 7 a private interconnection breaker connected to the branch point P side of the branch line 6, and 8 a branch line 6. A private generator 9 connected to the terminal side is a private load connected to the private generator 8 via the branch line 6.
[0011]
Reference numerals 10 and 11 denote first and second current detectors (CT1, CT2) provided in series with the branch line 6. Reference numeral 12 denotes a first current peak value detector that detects a peak value of a current flowing through the first current detector 10 on the distribution line side (hereinafter referred to as “system side”), and reference numeral 13 denotes a private generator 8 side (hereinafter referred to as “power generation”). The second current peak value detector 14 detects the peak value of the current flowing through the second current detector 11 (referred to as “machine side”), and 14 detects the integrated value of the current flowing through the first current detector 10 on the system side. 1 current integrated value detector, 15 a second current integrated value detector for detecting an integrated value of the current flowing through the second current detector 11 on the generator side, 16 a first and second current peak value detector 12, 13 and the first and second current integrated value detectors 14 and 15, and is an isolated operation determination unit that detects the isolated operation of the private power generation facility 2 from these detected values.
[0012]
Reference numerals 20 and 21 denote IGBTs which are a pair of semiconductor elements connected in the forward and reverse parallel to the line a between the first and second current detectors 10 and 11 in the branch line 6, and 22 denotes one end connected to the pair of IGBTs 20 and 21. The other end of the detection load capacitor is connected to the detection load capacitor 23, one end is connected to the detection load capacitor 22, the other end is connected to the grounded discharge resistor 24, and the other end is connected to the detection load capacitor 22. The other end is a switch connected to the charge discharging resistor 23.
Reference numeral 25 denotes a zero-cross point detection circuit that detects a zero-cross point of the current flowing through the branch line 6, and reference numeral 26 denotes a pair of IGBTs 20 and 21 that are turned on / off based on the zero-cross point detected by the zero-cross point detection circuit 28. This is a switch drive circuit to be turned off.
[0013]
First, an outline of the principle by which the independent operation of the private power generation facility 2 can be detected by the single operation detection device for the private power generation facility according to Embodiment 1 of the present invention will be described with reference to FIG. 2 that are substantially the same as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.
For example, the electric power required by the private load 9 in the private power generation facility 2 is supplied while driving the private generator 8. And if the electric power of the private load 9 becomes more than the output of the private generator 8, the insufficient electric power is supplied from the grid power company 1 to the private load 9 via the personal interconnection breaker 7.
Further, when the load capacity of the private load 9 decreases and surplus power is generated at the output of the private generator 8, the surplus power is automatically supplied from the private interconnection breaker 7 to the grid power company 1 side which is the power supply side. The surplus power is sold to the grid power company 1 by reverse tide.
[0014]
By the way, when the private power generation facility 2 is connected to the grid power company 1 side and is healthy and normal, and when the private power generation facility 2 is operating alone, the private power generation facility 2 is operating alone. As shown in FIG. 2, when a detection load capacitor 22 is instantaneously inserted into the branch line 6 provided between the distribution line 3 on the system power company 1 side and the private generator 8, the system of the branch line 6 Since the peak values of the currents flowing between the power supply side and the generator side are different from each other, it is determined whether the connection is normal based on the peak value or the case of independent operation.
Here, when the power generation facility 2 for private use is in an unhealthy state during interconnection with the grid power company 1 side, a fault occurs on the grid power company 1 side, and the grid breaker 4 is opened. Or the distribution line 3 is disconnected.
[0015]
When the private power generation facility is connected to the grid power company and is healthy and normal, when the switch S is turned on at the zero crossing point of the current flowing through the branch line 6 and the detection load capacitor 22 is instantaneously turned on. When the first and second current detectors 10 and 11 detect the current flowing in the system side and the generator side of the branch line 6, the current waveform is as shown by the broken line in FIG. The peak value of the current detected by the second current detector 11 (CT2) on the side changes only slightly, but the peak value of the current detected by the first current detector 10 (CT1) on the system side may change greatly. I understand.
This is because the current from the system side in addition to the current ig from the generator side when the detection load capacitor 22 is momentarily turned on when the generated current of the private generator 8 flows from the generator side to the system side. This is because ik flows into the detection load capacitor 22 and ik is much larger than ig, which is considered to be due to a decrease in the current detected by the first current detector 10 (CT1).
[0016]
Next, when the private power generation facility is in an unhealthy state during the interconnection with the grid power company and the private power generation facility is operating alone, the switch 12 is turned on at the zero crossing point of the current flowing through the branch line 6. When the first and second current detectors 10 and 11 detect the current flowing through the system side and the generator side of the branch line 6 when the detection load capacitor 22 is turned on instantaneously, the current is detected. As shown by the broken line in FIG. 3B, the waveform shows only a small change in the peak value of the current detected by the first current detector 10 (CT1) on the grid side, but the second current on the generator side. It has been found that the peak value of the current detected by the detector 11 (CT2) varies greatly.
[0017]
This is because the current ik from the system side does not flow until the detection load capacitor 22 is momentarily turned on when the generated current of the private generator 8 is flowing from the generator side to the system side. However, the current ig from the generator side is considered to be due to an increase in the current detected by the second current detector 11 (CT2) because it flows more than the detection load capacitor 22 is inserted. It is.
Therefore, by looking at the change in the peak value of the current detected by the first current detector 10 or the second current detector 11, the normal power generation system connected to the grid power company side and the normal power It is possible to determine whether the private power generation facility is operating alone in an unhealthy state during the connection with the company.
[0018]
Next, operation | movement of the independent operation | movement detection apparatus of the private generation equipment of Embodiment 1 of this invention is demonstrated.
First, in the state where the pair of IGBTs 20 and 21 are turned off, a part of the current flowing in the branch line 6 does not flow to the detection load capacitor 22, and therefore there is no detection load capacitor 22. Even if the current flowing in the branch line 6 is detected by the first and second current detectors 10 and 11, the detected values are the same. This is the same even during normal operation during grid connection or during abnormal operation.
[0019]
Next, the IGBT 20 is turned on and the IGBT 21 is turned off until the positive half cycle ends from the zero crossing point where the positive half cycle starts during one cycle of the current flowing through the branch line 6. The IGBT 20 is turned off and the IGBT 21 is turned on until the negative half cycle ends from the zero cross point at which the half cycle starts.
Then, a positive current flows through the detection load capacitor 22 during the positive half cycle, and a negative current flows through the detection load capacitor 22 during the next negative half cycle.
As described above, the first current detector 10 or the second current detector 11 detects the change in the current flowing through the branch line 6 when the positive and negative currents flow through the detection load capacitor 22 to detect the isolated operation. .
[0020]
However, when positive and negative currents are passed through the detection load capacitor 22, when the positive half-cycle current and the negative half-cycle current are exactly equal, no residual charge remains in the detection load capacitor 22. To be exact, the current in the positive half cycle and the current in the negative half cycle are not exactly equal, and since there is usually a large amount of any current, a residual charge remains in the detection load capacitor 22. Become.
Accordingly, when positive and negative currents are allowed to flow through the detection load capacitor 22 over several cycles, a residual charge gradually accumulates in the detection load capacitor 22, causing a situation in which no current flows through the detection load capacitor 22.
Therefore, after passing positive and negative currents through the detection load capacitor 22 for several cycles, it is necessary to remove the residual charge accumulated in the detection load capacitor 22.
For this reason, for example, in the first few seconds, positive and negative currents are supplied to the detection load capacitor 22 in the first few cycles, and in the next few cycles, residual charges accumulated in the detection load capacitor 22 are removed, When the set number of times is repeated 3 to 5 times per second, and the set number of times is detected continuously, it is determined that the operation is independent and an abnormal signal is output.
[0021]
The above operation will be described in detail with reference to FIG.
The switch drive circuit 26 receives the zero cross point detection signal from the zero cross point detection circuit 25.
Therefore, the switch drive circuit 26 turns on the IGBT 20 from the zero cross point where the positive half cycle starts during one cycle of the current flowing through the branch line 6 in one second until the positive half cycle ends. The IGBT 21 is turned off, and the IGBT 20 is turned off and the IGBT 21 is turned on until the negative half cycle ends from the zero cross point at which the next negative half cycle starts.
Then, a positive current flows through the detection load capacitor 22 during the positive half cycle, and a negative current flows through the detection load capacitor 22 during the next negative half cycle.
Then, the current peak value detected by the first and second current peak value detectors 12 and 13 from the current detected by the first and second current detectors 10 and 11 at this time, and the first and second currents. The integral value of the current detected by the integral value phase detectors 14 and 15 is input to the isolated operation determination unit 16.
[0022]
The isolated operation determination unit 16 detects the peak value of the positive or negative half cycle of the current detected by the first current peak value detector 12 when the current flows through the detection load capacitor 22 during one cycle. Compare the positive or negative half-cycle peak value of the current detected by the first current peak value detector 12 when no current is flowing through the load capacitor 22 and the current flows through the detection load capacitor 22 The first current peak value detector 12 when the positive or negative half-cycle peak value of the current detected by the first current peak value detector 12 is not flowing through the detection load capacitor 22 is When the difference between the peak values A1 is larger than a predetermined value A1ref in a state where the detected current is less than the positive or negative half cycle peak value, the private power generation facility 2 It can be determined that it is connected to the company 1 side and is healthy and normal. When the difference A1 between the two peak values is smaller than the predetermined value A1ref, the private power generation facility 2 is connected to the grid power company 1 side. It can be determined that the vehicle is in an unhealthy abnormal state and is operating alone.
[0023]
Further, the positive or negative half-cycle peak value of the current detected by the second current peak value detector 13 when the current flows through the detection load capacitor 22 during one cycle and the detection load capacitor 22 The second current peak value detector 13 when the current is not flowing is compared with the peak value of the positive or negative half cycle of the current detected by the second current peak detector 13, and the second when the current is flowing through the detection load capacitor 22. The positive or negative half-cycle peak value of the current detected by the current peak value detector 13 is positive when the current peak value detected by the second current peak value detector 13 is not flowing through the detection load capacitor 22. Or, when the difference A2 between the two peak values is larger than the predetermined value A2ref when the peak value of the negative half cycle is increased, the private power generation facility 2 is not connected to the grid power company 1 side. It can be determined that the vehicle is in a sound abnormal state and is operating independently. When the difference A2 between the peak values is smaller than the predetermined value A2ref, the private power generation facility 2 is connected to the grid power company 1 side. And can be determined to be healthy and normal.
Note that the positive or negative half-cycle peak value of the current detected by the first current peak value detector 12 and the second current peak value detector 13 when no current flows through the detection load capacitor 22 is used alone. The operation determination unit 16 may store the predetermined reference value.
[0024]
In addition, in the isolated operation determination unit 16, the current of positive or negative half cycle of the current detected by the first current integrated value detector 14 when the current flows through the detection load capacitor 22 during one cycle. The integral value is compared with the integral value of the positive or negative half cycle of the current detected by the first current integral value detector 14 when no current is flowing through the detection load capacitor 22. The first current integral value when the positive or negative half cycle integral value of the current detected by the first current integral detector 14 when the current is flowing is not flowing through the detection load capacitor 22. When the difference A3 between both integral values is larger than a predetermined value A3ref in a state where the current detected by the detector 14 is less than the integral value of the positive or negative half cycle, the private power generation facility 2 is connected to the grid power company 1 side. When the difference A3 between the two integrated values is smaller than the predetermined value A3ref, the private power generation facility 2 is unhealthy during the grid connection with the grid power company 1 side. It can be determined that the vehicle is in an abnormal state and is operating alone.
[0025]
Further, the positive or negative half-cycle integral value of the current detected by the second current integral value detector 15 when the current flows through the detection load capacitor 22 during one cycle and the detection load capacitor 22 The second current integrated value detector 15 when the current is not flowing is compared with the integrated value of the positive or negative half cycle of the current detected by the second current integrated value detector 15, and the second when the current is flowing through the detection load capacitor 22. The positive or negative half cycle integrated value of the current detected by the current integrated value detector 15 is positive when the current detected by the second current integrated value detector 15 is not flowing through the detection load capacitor 22. Or, when the difference A4 between the two integral values is larger than the predetermined value A4ref in a state where the integral value of the negative half cycle is larger than the predetermined value A4ref, an unhealthy abnormality occurs when the private power generation facility 2 is connected to the grid power company 1 side. State and Therefore, when the difference A4 between the two integrated values is smaller than the predetermined value A4ref, the private power generation facility 2 is connected to the grid power company 1 side and is healthy and normal. It can be determined as a case.
The integral value of the positive or negative half cycle of the current detected by the first current integral value detector 114 and the second current integral value detector 15 when no current flows through the detection load capacitor 22 is used alone. The driving determination unit 16 may store the predetermined reference value in advance.
[0026]
Then, the isolated operation determination unit 16 according to the first embodiment performs determination based on the current peak value detected by the first current peak value detector 12 or determination based on the current peak value detected by the second current peak value detector 13. In addition, when the determination based on the peak value of the current detected by the first and second current peak value detectors 12 is the same, or the determination based on the integrated value of the current detected by the first current integrated value detector 14 or the first When the determination based on the integrated value of the current detected by the first and second current integrated value detectors 15 is the same as well as the determination based on the integrated value of the current detected by the two current integrated value detector 15, the first further When the determination based on the peak value of the current detected by the second current peak value detectors 12 and 13 and the determination based on the integrated value of the current detected by the first and second current integrated value detectors 14 and 15 are the same, Each home When the power generation facility 2 is connected to the grid power company 1 and is healthy and normal, and the power generation facility 2 is connected to the grid power company 1 and is unhealthy and abnormal, the private power generation facility 2 is operated independently. Judgment is divided into cases where
[0027]
This is because the determination can be made more accurately by judging from these two or three viewpoints.
Therefore, when it is determined that the private power generation facility 2 is operating alone in an unhealthy state while the private power generation facility 2 is connected to the grid power company 1 side, the private power generation facility 2 is immediately connected to the grid power company. It is possible to prevent the occurrence of various accidents such as damage to equipment on the private power generation equipment 2 side or accidents during maintenance and inspection of the distribution line 3 on the grid power company 1 side.
[0028]
As a result, the private generator 8 can supply electric power to the private load 9 in the facility while continuously operating, and the system-side circuit breaker 4 and other breakers are opened due to a failure, and the private generator 8 is privately connected to the unloaded electric line 3. Failure inspection and restoration can be performed safely without power being transmitted by the generator 8 or the like.
Moreover, even if the system side circuit breaker 4 on the system power company 1 side is closed immediately after the failure of the distribution line 3 is repaired, the equipment on the side of the private power generation facility 2 is damaged if the private interconnection circuit breaker 7 is opened. Without any problem, the self-generator 8 has the voltage, frequency, phase, etc. accurately synchronized with the grid power company 1 side using a synchronous tester, etc., and then closes the self-interconnection breaker 7 and connects it to the private power generation facility. 2 is connected to the grid power company 1 side to restore normal state
[0029]
As described above, theoretically, when positive and negative currents are passed through the detection load capacitor 22, if the positive half-cycle current and the negative half-cycle current are completely equal, the detection load capacitor 22 remains in the detection load capacitor 22. There is no charge remaining, but the positive half-cycle current and the negative half-cycle current are not exactly the same, and it is usual that there is a large amount of either current, so the detection load capacitor Thus, a residual charge remains in 22.
[0030]
Therefore, for example, in order to pass a current through the detection load capacitor 22 at first in one second, the switch drive circuit 26 starts from the zero cross point at which the positive half cycle starts during one cycle of the current flowing through the branch line 6. The IGBT 20 is turned on until the positive half cycle ends, the IGBT 21 is turned off, and the IGBT 20 is turned off and the IGBT 21 is turned on until the negative half cycle ends from the zero cross point at which the next negative half cycle starts. Repeat several cycles. At this time, the switch drive circuit 26 keeps the switch 24 off.
[0031]
Thereafter, the switch drive circuit 26 turns off both the IGBT 20 and the IGBT 21 and turns on the switch 24 for several cycles.
As a result, the residual charge accumulated in the detection load capacitor 22 is discharged by the charge discharging resistor 23, so that the residual charge accumulated in the detection load capacitor 22 is removed. Therefore, these are repeated 3 to 5 times per second, and when the set number of times is detected continuously, it is determined that the vehicle is operating independently and an abnormal signal is output.
Since a current flows through the detection load capacitor 22 with reference to the zero cross point, no surge current or arc is generated, and the detection load capacitor 22 is not destroyed.
In addition, the power consumed by the detection load capacitor 22 is much less than that of the detection load resistor, and since the heat generation is small, the detection load capacitor 22 is smaller than the detection load resistor, and the entire apparatus It is also possible to reduce the size.
[0032]
In the first embodiment, the islanding determination unit 16 determines the current peak value detected by the first current peak value detector 12 or the current peak value detected by the second current peak value detector 13. However, it goes without saying that the average value or the effective value can be calculated based on the peak value of the current and can be determined based on the average value or the effective value.
[0033]
In addition, the isolated operation determination unit 16 is determined based on the integrated value of the current detected by the first current integrated value detectors 14 and 15 or is determined based on the integrated value of the current detected by the second current integrated value detector 15. Compared to the determination based on the peak value of the current detected by the first current peak value detector 12 or the determination based on the peak value of the current detected by the second current peak value detector 13, the integrated value of the current is obtained. This is because there are few malfunctions.
[0034]
【The invention's effect】
According to claim 1 of the present invention, the first and second current detectors provided in series with the branch line provided between the distribution line on the grid power company side and the private generator, and the branch line A load capacitor for detection connected via a pair of semiconductor elements connected in a forward and reverse parallel to the line between the first and second current detectors, and a switch at a connection point between the pair of semiconductor elements and the load capacitor for detection A charge discharging resistor connected via A first current peak value detector that detects the peak value of the current flowing through the first current detector on the distribution line side and a first peak value of the current that flows through the second current detector on the private generator side. Two current peak value detectors; Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at each zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. And a switch control circuit that controls to turn on the single operation determination unit when the current is flowing through the detection load capacitor The peak value of the current of at least one cycle detected by the first current peak value detector, or an average value or effective value based on the peak value of the current is substantially the same as a predetermined value, or detected by the second current peak value detector The average value or the effective value based on the peak value of the current of at least one cycle or the peak value of the current is When it is greater than the predetermined value, it can be determined that the private power generation facility is operating alone, so if it is determined that the private power generation facility is operating independently, the private power generation facility is immediately separated from the grid power company side, It has the effect of preventing the occurrence of various accidents such as damage to equipment on the private power generation facility side or accidents during maintenance inspection of distribution lines on the grid power company side.
In addition, even if the switch is opened from the closed state, the detection load capacitor is opened with no electric charge, so that no arc is generated, the detection load capacitor is not destroyed, and the detection load capacitor is consumed. The electric power is much smaller than the detection load resistance, and since the heat generation is small, the detection load capacitor is small, and the entire apparatus can be reduced in size.
[0035]
In addition, the switch control circuit alternately turns on and off the pair of semiconductor elements at every zero cross point for several cycles out of the one second cycle of the current flowing through the branch line, and the pair of semiconductors for the subsequent several cycles. Since the device is controlled to be turned off and the switch is turned on, a current flows through the detection load capacitor with reference to the zero cross point, and no surge current or arc is generated, and the detection load capacitor is not destroyed. Since the residual charge accumulated in the detection load capacitor is discharged by the residual charge discharge resistor, the residual charge is not adversely affected, and the power consumed by the detection load capacitor is much larger than that of the detection load resistor. The load capacitor for detection can be small because it requires less heat and generates less heat, and the entire device can be downsized. There is an effect that.
[0036]
According to claim 2 of the present invention, the first and second current detectors provided in series with the branch line provided between the distribution line on the grid power company side and the private generator, and the branch line A load capacitor for detection connected via a pair of semiconductor elements connected in a forward and reverse parallel to the line between the first and second current detectors, and a switch at a connection point between the pair of semiconductor elements and the load capacitor for detection A charge discharging resistor connected via A first current integrated value detector that detects an integrated value of the current flowing through the first current detector on the distribution line side, and a first current detector that detects an integrated value of the current flowing through the second current detector on the private generator side. Two current integral detectors; Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at each zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. A switch control circuit that controls to turn on, and the islanding determination unit when the current flows through the detection load capacitor The integrated value of the current of at least one cycle detected by the first current integrated value detector is substantially the same as the predetermined value, or the integrated value of the current of at least one cycle detected by the second current integrated value detector is When it is greater than the predetermined value, it can be determined that the private power generation facility is operating alone, so if it is determined that the private power generation facility is operating independently, the private power generation facility is immediately separated from the grid power company side, It has the effect of preventing the occurrence of various accidents such as damage to equipment on the private power generation facility side or accidents during maintenance inspection of distribution lines on the grid power company side.
[0037]
In addition, the switch control circuit alternately turns on and off the pair of semiconductor elements at every zero cross point for several cycles out of the one second cycle of the current flowing through the branch line, and the pair of semiconductors for the subsequent several cycles. Since the device is controlled to be turned off and the switch is turned on, a current flows through the detection load capacitor with reference to the zero cross point, and no surge current or arc is generated, and the detection load capacitor is not destroyed. Since the residual charge accumulated in the detection load capacitor is discharged by the residual charge discharge resistor, the residual charge is not adversely affected, and the power consumed by the detection load capacitor is much larger than that of the detection load resistor. The load capacitor for detection can be small because it requires less heat and generates less heat, and the entire device can be downsized. There is an effect that.
[Brief description of the drawings]
FIG. 1 is a single line connection diagram illustrating a configuration of an isolated operation detection device for a private power generation facility according to a first embodiment of the present invention.
FIG. 2 is a single-line diagram showing the basic configuration of the isolated operation detection device.
FIG. 3 is a waveform diagram schematically illustrating a current flowing from a branch line of the islanding detection device to a load capacitor for detection.
FIG. 4 is a waveform diagram for explaining residual charges generated in a detection load capacitor of the isolated operation detection device for the private power generation facility.
[Explanation of symbols]
1 Power company
2 Private power generation facilities
3 Distribution lines
6 branch line
8 Private generator
9 Private load
10 First current detector (CT1)
11 Second current detector (CT2)
12 First current peak value detector
13 Second current peak value detector
14 First current integral detector
15 Second current integrated value detector
16 Independent operation determination unit
20 IGBT (semiconductor element)
21 IGBT (semiconductor element)
22 Load capacitor for detection
23 Charge discharge resistance
25 Zero cross point detection circuit
26 Switch drive circuit

Claims

It is a private power generation facility having a private load that is supplied with power from the grid power company that supplies power via a distribution line and that is mainly supplied with power from a private generator,
First and second current detectors provided in series with a branch line provided between a distribution line on the grid power company side and a private generator;
A load capacitor for detection connected via a pair of semiconductor elements connected in forward and reverse parallel to a line between the first and second current detectors in the branch line;
A charge discharge resistor connected via a switch to a connection point between the pair of semiconductor elements and the load capacitor for detection;
A first current peak value detector for detecting a peak value of a current flowing through the first current detector on the distribution line side;
A second current peak value detector for detecting a peak value of a current flowing through the second current detector on the private generator side;
Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at every zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. A switch control circuit for controlling to turn on,
Whether at least one cycle of the current peak value detected by the first current peak value detector when current is flowing through the detection load capacitor, or an average value or effective value based on the current peak value is substantially the same as a predetermined value Or, when the peak value of the current of at least one cycle detected by the second current peak value detector or the average value or effective value based on the peak value of the current is larger than a predetermined value, it is determined that the private power generation facility is in a single operation. An independent operation detection device for a private power generation facility, characterized by comprising an isolated operation determination unit.

It is a private power generation facility having a private load that is supplied with power from the grid power company that supplies power via a distribution line and that is mainly supplied with power from a private generator,
First and second current detectors provided in series with a branch line provided between a distribution line on the grid power company side and a private generator;
A load capacitor for detection connected via a pair of semiconductor elements connected in forward and reverse parallel to a line between the first and second current detectors in the branch line;
A charge discharge resistor connected via a switch to a connection point between the pair of semiconductor elements and the load capacitor for detection;
A first current integrated value detector for detecting an integrated value of a current flowing through the first current detector on the distribution line side;
A second current integrated value detector for detecting an integrated value of a current flowing through the second current detector on the private generator side;
Among several cycles of the current flowing through the branch line, the pair of semiconductor elements are alternately turned on and off at each zero cross point for several cycles, and the pair of semiconductor elements are turned off and switched for several cycles thereafter. A switch control circuit for controlling to turn on,
The integrated value of the current of at least one cycle detected by the first current integrated value detector when the current is flowing through the detection load capacitor is substantially the same as the predetermined value or detected by the second current integrated value detector. An independent operation detection device for private power generation facilities, comprising: an independent operation determination unit that determines that the private power generation facility is in a single operation when the integral value of the current of at least one cycle is greater than a predetermined value.