JP5600016B2 - Automatic synchronous parallel device - Google Patents

Description

  The present invention relates to an automatic synchronous parallel device that adjusts the voltage amplitude, frequency, and phase of a single-phase voltage type AC / DC converter that performs autonomous parallel operation.

  A technique for suppressing an inrush current when an inverter is paralleled to a power system is known (see, for example, Patent Document 1). Patent Document 1 discloses a technique in which a filter capacitor of an inverter is charged with a current whose phase is advanced by 90 degrees from the voltage of the power system, and the inverter is paralleled to the power system after the voltage of the filter capacitor becomes the same as that of the power system. be written.

  On the other hand, a single-phase voltage type AC / DC converter that performs autonomous parallel operation in parallel with a single-phase voltage source such as a power system or a generator is also known (see, for example, Patent Document 2). In Patent Document 2, a single-phase AC voltage having a predetermined phase difference from the phase of an external single-phase AC voltage source is generated, and the amplitude, frequency, and phase of the generated single-phase AC voltage are adjusted to obtain an external single-phase voltage. A single-phase voltage type AC / DC converter that is linked to an AC voltage source is described.

JP 09-028040 A JP 2009-219263 A

  A single-phase voltage type AC / DC converter that performs autonomous parallel operation is controlled to be a voltage source when viewed from a single-phase voltage source side such as a power system or a generator. When a single-phase voltage-type AC / DC converter that performs autonomous parallel operation is paralleled with this external single-phase AC voltage source, the single-phase voltage-type AC / DC converter is connected to the constantly changing frequency and voltage amplitude of the single-phase voltage source to suppress inrush current. It is necessary to follow the output of the converter. However, since the technique of Patent Document 1 controls the inverter to be a current source, it cannot be applied to a single-phase voltage type AC / DC converter controlled to be a voltage source. In this way, the technology of automatically synchronizing and paralleling the output of a single-phase voltage type AC / DC converter that performs autonomous parallel operation follows the frequency and voltage amplitude of a constantly changing single-phase voltage source and suppresses inrush current. There was a problem that it did not exist.

  In order to solve the above problems, the present invention automatically adjusts the magnitude, frequency, and phase of a voltage when a single-phase voltage type AC / DC converter that performs autonomous parallel operation is paralleled to an external single-phase AC voltage source. It aims at providing the automatic synchronous parallel apparatus which can suppress an inrush current by this.

  In order to achieve the above object, an automatic synchronous parallel device according to the present invention includes a value relating to a frequency difference between an external single-phase AC voltage source and a single-phase voltage type AC / DC converter, and an effective voltage value of the external single-phase AC voltage source. A single-phase voltage type AC / DC converter so that the effective voltage value approaches the effective voltage value of the external single-phase AC voltage source, and the frequency deviates from the frequency of the external single-phase AC voltage source by an arbitrary value. I decided to control it.

  Specifically, the automatic synchronous parallel device according to the present invention performs autonomous parallel operation based on a uniaxial voltage command value for adjusting the amplitude of the output single-phase AC voltage waveform and a biaxial voltage command value for adjusting the frequency. A value relating to a frequency difference between the external single-phase AC voltage source to be paralleled by the single-phase voltage AC / DC converter and the single-phase voltage AC / DC converter, and a value relating to a voltage effective value of the external single-phase AC voltage source are detected. And the uniaxial voltage command value that brings the effective single-phase AC voltage value of the single-phase voltage type AC / DC converter close to the effective voltage value of the external single-phase AC voltage source detected by the synchronous verification circuit. Then, using the voltage amplitude command value generation circuit that is input to the single-phase voltage type AC / DC converter and the value relating to the frequency difference detected by the synchronization verification circuit, the single-phase AC voltage of the single-phase voltage type AC / DC converter is obtained. Frequency to the outside Comprising a frequency command value generating circuit for inputting phase AC voltage source to generate the two-axis voltage command value to the frequency shifted any frequency value from frequency to the single-phase voltage-AC-DC conversion device.

  The voltage command value generation circuit generates a uniaxial voltage based on the value related to the frequency difference between the external single-phase AC voltage source and the single-phase voltage AC / DC converter detected by the synchronization verification circuit and the effective voltage value of the external single-phase AC voltage source. A command value is generated, and a frequency command value generation circuit generates a biaxial voltage command value. With these command values, the output of the single-phase voltage type AC / DC converter can be matched with the voltage waveform of the external single-phase AC voltage source.

  Therefore, the automatic synchronous parallel device according to the present invention automatically adjusts the magnitude, frequency, and phase of the voltage when the single-phase voltage type AC / DC converter that performs autonomous parallel operation is paralleled to the external single-phase AC voltage source. Thus, inrush current can be suppressed.

  The voltage amplitude command value generation circuit of the automatic synchronous parallel device according to the present invention outputs the single-phase voltage type AC / DC converter from a value relating to a voltage effective value of the external single-phase AC voltage source detected by the synchronous verification circuit. Automatic parallel control of the voltage system subtractor that subtracts the value related to the voltage effective value of the single-phase AC voltage waveform, the voltage system integrator that integrates the value subtracted by the voltage system subtractor, and the external single-phase AC voltage source is started. A voltage system adder that generates the uniaxial voltage command value by adding a single-phase AC voltage initial value of the previous single-phase voltage type AC / DC converter and a value integrated by the voltage system integrator; It is characterized by.

  The frequency command value generation circuit of the automatic synchronous parallel device according to the present invention includes a value obtained by multiplying a value related to a voltage effective value of the external single-phase AC voltage source detected by the synchronization test circuit by the arbitrary frequency value. Automatic parallel control of a frequency system calculator for adding a value related to the frequency difference detected by the test circuit, a frequency system integrator for integrating the value calculated by the frequency system calculator, and the external single-phase AC voltage source is started. A frequency system adder that adds the initial frequency of the single-phase AC voltage of the single-phase voltage type AC / DC converter before and a value integrated by the frequency system integrator to generate the biaxial voltage command value; It is characterized by that.

  The value related to the effective voltage value of the automatic synchronous parallel device according to the present invention is preferably a square value of the effective voltage value.

  In the synchronous verification circuit of the automatic synchronous parallel device according to the present invention, the voltage effective value and frequency of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter are respectively the voltage effective value and frequency of the external single-phase AC voltage source. The single-phase voltage type AC / DC converter and the external single-phase AC voltage source are arranged in parallel when they are within a predetermined prescribed range centering on.

  Overshooting can be avoided by limiting the range of conditions for paralleling the single-phase voltage type AC / DC converter to the external single-phase AC voltage source.

  The present invention automatically controls the inrush current by automatically adjusting the voltage magnitude, frequency, and phase when a single-phase voltage type AC / DC converter that performs autonomous parallel operation is paralleled to an external single-phase AC voltage source. A synchronous parallel device can be provided.

It is a block diagram explaining the automatic synchronous parallel apparatus which concerns on this invention. It is a block diagram explaining an example of a synchronous verification circuit. It is a figure explaining the logic for paralleling the single phase voltage type | mold AC / DC converter which the automatic synchronous parallel apparatus which concerns on this invention performs to an external single phase alternating voltage source. It is a figure explaining the logic for separating the single phase voltage type | mold AC / DC converter which the automatic synchronous parallel apparatus which concerns on this invention performs from an external single phase alternating voltage source. When the automatic synchronous parallel device according to the present invention parallels the single-phase voltage type AC / DC converter to the external single-phase AC voltage source, the uniaxial voltage command value, the biaxial voltage command value, and the single-phase voltage type AC / DC converter It is the result of simulating a single-phase voltage waveform. It is the result of having measured the single phase voltage waveform of the single phase voltage type AC / DC converter, the voltage waveform of the external single phase AC voltage source, and the output current of the single phase voltage type AC / DC converter before and after parallel.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  FIG. 1 is a block diagram illustrating the automatic synchronous parallel device 17 of the present embodiment. FIG. 1 shows a single-phase voltage type AC / DC converter 11 that performs autonomous parallel operation, an external single-phase AC voltage source 12 in parallel with this, and a single-phase voltage type AC / DC converter 11 and an external single-phase AC voltage source 12 in parallel. In addition, an interconnection switch 15 for disconnecting is also described. The external single-phase AC voltage source 12 is, for example, a power system or a generator.

ここで、Ｖ_ｉ及びω_ｉはそれぞれ単相電圧型交直変換装置１１の電圧実効値及び検定元角周波数である。この実効値Ｖ_ｉ及び位相角ωｔ＝θ_ｉは、１軸電圧指令値Ｖ_１ ^＊（ｔ）及び２軸電圧指令値Ｖ_２ ^＊（ｔ）からなる上位指令ベクトル１２０で次のように決定される。

ここで、Ｅ_ｃｏは規準電圧、Ｋ_ｍｕ１は１軸電圧ゲイン、Ｋ_ｍｕ２は２軸電圧ゲイン、Ｋ_ｆはフェーズロックドループ（ＰＬＬ）ゲインである。 The single-phase voltage type AC / DC converter 11 is a single-phase voltage type AC / DC converter described in Patent Document 2 that performs autonomous parallel operation. The output terminal voltage V ₁ (t) of the single-phase voltage type AC / DC converter 11 performing no-load single operation can be expressed by the following equation.

Here, V _i and ω _i are a voltage effective value and a verification source angular frequency of the single-phase voltage type AC / DC converter 11, respectively. The effective value V _i and the phase angle ωt = θ _i are determined by the upper command vector 120 composed of the uniaxial voltage command value V ₁ ^* (t) and the biaxial voltage command value V ₂ ^* (t) as follows. The

_{Here, E co} is reference _{voltage, K mu1} one axis voltage _{gain, K mu2} biaxial voltage gain, the _{K f} is a phase-locked loop (PLL) gain.

Here, θ _i advances when the biaxial voltage command value V ₂ ^* of the inverter increases, and delays when it decreases. V _i is 1-axis voltage command value _V ^{1 *} is increased the larger the smaller the smaller. That is, V ₁ (t) can be independently changed in amplitude, frequency, and phase by V ₁ ^* and V ₂ ^* .

In order to parallelize the single-phase voltage type AC / DC converter 11 to the external single-phase AC voltage source 12, the following procedure is performed using the automatic synchronous parallel device 17.
[1] The automatic synchronous parallel device 17 controls the uniaxial voltage command value V ₁ ^* (t) and outputs the effective value V _i (t) of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11 to the outside. The voltage is adjusted to the effective voltage value Vs of the single-phase AC voltage source 12.
[2] The automatic synchronous parallel device 17 controls the biaxial voltage command value V ₂ ^* (t) to set the single-phase AC voltage angular frequency dθi (t) / dt of the single-phase voltage type AC / DC converter 11 to an external single unit. It is set to a value ω _s + Δω ₀ shifted by Δω ₀ from the angular frequency ω _s of the phase AC voltage source 12. Δω ₀ ≠ ₀ rad / s. When Δω ₀ = ₀ rad / s, the automatic synchronous parallel device 17 cannot match the phase of the single-phase voltage type AC / DC converter 11 with the external single-phase AC voltage source 12. Δω ₀ is positive when the external single-phase AC voltage source 12 is an inverter, and negative when the external single-phase AC voltage source 12 is a rectifier. For example, Δω ₀ = 0.3 rad / s (0.0478 Hz).
[3] The single-phase AC voltage effective value V _i (t) of the single-phase voltage type AC / DC converter 11 is within a predetermined specified range ΔV _s centered on the voltage effective value V _s of the external single-phase AC voltage source 12 (V _s + ΔV _s ) and ω _s (t) −θ _i (t) is in the range of ± Δθ _i , and the state continues for a predetermined time T _detect , the automatic synchronous parallel device 17 is switched to the switch 15 Is commanded. The values of ΔV _s , Δθ _i , and T _detect will be described later.

In order to parallelize the single-phase voltage type AC / DC converter 11 to the external single-phase AC voltage source 12 as described above, the automatic synchronous parallel device 17 is configured as follows. The automatic synchronous parallel device 17 includes a synchronization verification circuit 130, a voltage amplitude command value generation circuit 180, and a frequency command value generation circuit 190. The synchronization verification circuit 130 is a single-phase voltage that performs autonomous parallel operation based on the uniaxial voltage command value V ₁ ^* that adjusts the amplitude of the output single-phase AC voltage waveform and the biaxial voltage command value V ₂ ^* that adjusts the frequency. The value [(ω _s −ω) V _s or (ω _s −ω) V _s ² ] regarding the frequency difference between the external single-phase AC voltage source 12 and the single-phase voltage type AC / DC converter 11 in parallel with the AC / DC converter 11. And a value [V _s or V _s ² ] related to the effective voltage value of the external single-phase AC voltage source 12 is detected. The voltage amplitude command value generation circuit 180 brings the single-phase AC voltage effective value V _i of the single-phase voltage type AC / DC converter 11 close to the voltage effective value V _s of the external single-phase AC voltage source 12 detected by the synchronization verification circuit 130 1 A shaft voltage command value V ₁ ^* is generated and input to the single-phase voltage type AC / DC converter 11. The frequency command value generation circuit 190 converts the single-phase AC voltage frequency of the single-phase voltage type AC / DC converter 11 from the frequency of the external single-phase AC voltage source 12 to an arbitrary frequency using a value related to the frequency difference detected by the synchronization verification circuit 130. A biaxial voltage command value V ₂ ^* having a frequency shifted by the value Δω ₀ is generated and input to the single-phase voltage type AC / DC converter 11.

The synchronization verification circuit 130 includes a value [(ω _s −ω) V _s or (ω _s −ω) V _s ² ] regarding a frequency difference between the external single-phase AC voltage source 12 and the single-phase voltage type AC / DC converter 11, and What is necessary is just to be able to detect the value [V _s or V _s ² ] related to the voltage effective value of the external single-phase AC voltage source 12. FIG. 2 is a block diagram for explaining an example of the synchronization verification circuit 130.

FIG. 2 is a diagram for explaining the synchronization verification circuit 130. The synchronization verification circuit 130 includes a reference angular frequency ω _co , a sampler 133 that detects the voltage waveform to be tested of the external single-phase AC voltage source 12, and the voltage waveform to be tested detected by the sampler 133 (m−1 / 2). π / ω _co (where m is a natural number) a delay circuit 134 that creates a delayed voltage waveform delayed in time, the test target external voltage waveform detected by the sampler 133, the delayed voltage waveform created by the delay circuit 134, and Further, the frequency difference cosine signal and the frequency having the angular frequency as the difference between the verification target angular frequency ω _s of the verification target external voltage waveform and the verification source angular frequency ω from the verification source angular frequency ω of the single-phase voltage type AC / DC converter 11. And an arithmetic unit 135 for calculating a difference sine signal.

In this embodiment, the synchronization verification circuit 130 has the reference angular frequency ω _co , but may be received from the single-phase voltage type AC / DC converter 11 that is the verification source.

ここで、Ｖ_ｓは実効値［Ｖ］、ω_ｓは角周波数［ｒａｄ／ｓ］、φはインバータから見た外部交流電源のｔ＝０での位相角［ｒａｄ］である。
サンプラー１３３は、この検定対象外部電圧波形Ｖ_２（ｔ）をサンプリングする。ここで、検定対象電圧波形Ｖ_２（ｔ）をサンプリングしたサンプル波形をＶ_２（ｎＴｓ）と表す。Ｔｓはサンプル周期であり、ｎはサンプル番号である。 Further, the verification target voltage waveform V ₂ (t) of the external single-phase AC voltage source 12 to be verified can be expressed by the following equation.

Here, V _s is an effective value [V], ω _s is an angular frequency [rad / s], and φ is a phase angle [rad] at t = 0 of the external AC power source viewed from the inverter.
The sampler 133 samples the verification target external voltage waveform V ₂ (t). Here, a sample waveform obtained by sampling the verification target voltage waveform V ₂ (t) is represented as V ₂ (nTs). Ts is a sample period, and n is a sample number.

The delay circuit 134 receives the reference angular frequency ω _co and the delay voltage waveform V ₂ ^# (nTs) delayed from the sample waveform V ₂ (nTs) by a period of (m−1 / 2) π / ω _co (m is a natural number). ).

The delay amount of the delay voltage waveform V ₂ ^# (nTs) can be expressed as (m−1 / 2) π / ω _co . In the present embodiment, a case where m = 1 (a case where a quarter cycle is delayed) will be described. In this case, the delay voltage waveform V ₂ ^# (nTs) is expressed by the following equation.

The calculator 135 receives the verification source angular frequency ω from the single-phase voltage type AC / DC converter 11. The calculation unit 135 receives the sample waveform V ₂ (nTs) and the delayed voltage waveform V ₂ ^# (nTs), and calculates the difference between the verification source angular frequency ω and the verification target angular frequency ω _s of the external single-phase AC voltage source 12. A frequency difference cosine signal V ₃ (nTs) and a frequency difference sine signal V ₄ (nTs) are calculated as angular frequencies.

Specifically, the arithmetic unit 135 performs rotational coordinate conversion on the sample waveform V ₂ (nTs) and the delayed voltage waveform V ₂ ^# (nTs) as shown in Equation 5 to perform the frequency difference cosine signal V ₃ (nTs) and the frequency difference. The sine signal V ₄ (nTs) is calculated.

When the calculation unit 135 calculates, the frequency difference cosine signal V ₃ (nTs) and the frequency difference sine signal V ₄ (nTs) include a high frequency component having a frequency of (ω _s + ω). Therefore, the calculation unit 135 further includes low-pass filters (152A, 152B) that remove high-frequency components. The frequency difference cosine signal and the frequency difference sine signal from which high-frequency components have been removed by the low-pass filters (152A, 152B) are denoted as V _U3 (nTs) and V _U4 (nTs), respectively.

The synchronization verification circuit 130 further includes a detection unit 136. The detection unit 136 uses the frequency difference cosine signal V _U3 (nTs) and the frequency difference sine signal V _U4 (nTs) output from the calculation unit 135 to determine the effective voltage value of the verification target external voltage waveform V ₂ (t), frequency difference being tested external voltage waveform V ₂ and test object angular frequency omega _s of the _(t) test original angular frequency omega, and assay the target external voltage waveform V _{2 (t)} and test the original voltage waveform V _{1 (t)} Can be detected.

Specifically, the detection unit 136 detects the voltage effective value, the frequency difference, and the phase difference by the circuit 161 that calculates the equation 7, the circuit 162 that calculates the equation 8, and the circuit 163 that calculates the equation 9, respectively.

Next, the procedure [1] for paralleling the single-phase voltage type AC / DC converter 11 to the external single-phase AC voltage source 12 will be described. Step [1] is performed by the voltage amplitude command value generation circuit 180. The voltage amplitude command value generation circuit 180 outputs the single-phase voltage type AC / DC converter 11 that outputs the value [V _s or V _s ² ] related to the voltage effective value of the external single-phase AC voltage source 12 detected by the synchronization verification circuit 130. The voltage system subtractor 181 that subtracts the value [V _i or V _i ² ] related to the phase AC voltage effective value, the voltage system integrator 182 that integrates the value subtracted by the voltage system subtractor 181, and the external single-phase AC voltage source 12 The initial voltage value V ₁ ^* (0) of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11 immediately before the start of the automatic parallel control with the sum of the value integrated by the voltage integrator 182 is added to the uniaxial voltage And a voltage system adder 183 that generates a command value V ₁ ^* (t).

そこで、上式を利用して単相電圧型交直変換装置１１の１軸電圧指令値Ｖ_１ ^＊（ｔ）に次のような閉ループを施す。

ここで、初期値Ｖ_１ ^＊（０）は閉ループ制御を開始する直前のＶ_１ ^＊（ｔ）の値、Ｋ_ａｍｐ（＞０）は積分ゲインである。 As shown in the following equation, V _U3 ² (t) + V _U4 ² (t) is substantially equal to V _s ² .

Therefore, the following closed loop is applied to the uniaxial voltage command value V ₁ ^* (t) of the single-phase voltage type AC / DC converter 11 using the above equation.

Here, the initial value V ₁ ^* (0) is the value of V ₁ ^* (t) immediately before the start of the closed loop control, and K _amp (> 0) is the integral gain.

数２を用いて数１２をＶ_ｉ（ｔ）の方程式に変形する。

Ｖ_１ ^＊（０）は、自動並列制御開始直前の単相電圧型交直変換装置１１の電圧の実効値である。 Equations 10 to 11 can be approximated as follows.

Using Equation 2, Equation 12 is transformed into an equation of V _i (t).

V ₁ ^* (0) is an effective value of the voltage of the single-phase voltage type AC / DC converter 11 immediately before the start of automatic parallel control.

数１５を変形して下式を得る。

さらに積分定数Ｃを用いると、

となり、

となる。これを変形して次式を得る。

数１９から

となるので、この閉ループ制御によって時間の経過とともに単相電圧型交直変換装置１１の出力の電圧実効値はＶ_ｓに近づくことになる。 Differentiating both sides of Equation 14 yields the following differential equation for V _i .

Equation 15 is transformed to obtain the following formula.

Furthermore, if the integration constant C is used,

And

It becomes. This is transformed to obtain the following formula.

From number 19

Thus, with this closed loop control, the effective voltage value of the output of the single-phase voltage type AC / DC converter 11 approaches V _s as time passes.

Next, the procedure [2] for paralleling the single-phase voltage type AC / DC converter 11 to the external single-phase AC voltage source 12 will be described. Step [2] is performed by the frequency command value generation circuit 190. The frequency command value generation circuit 190 synchronizes a value obtained by multiplying a value [V _s or V _s ² ] related to the voltage effective value of the external single-phase AC voltage source 12 detected by the synchronization verification circuit 130 by an arbitrary frequency value Δω _0. A frequency system computing unit 191 for adding a value [(ω _s −ω) V _s or (ω _s −ω) V _s ² ] related to the frequency difference detected by the circuit 130, and integrating the value computed by the frequency system computing unit 191 The initial frequency V ₂ ^* (0) of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11 immediately before the start of automatic parallel control between the frequency-system integrator 192 and the external single-phase AC voltage source 12 and the frequency-system integration A frequency system adder 193 that generates a biaxial voltage command value V ₂ ^* (t) by adding the values integrated by the unit 192.

そこで、上式を利用して単相電圧型交直変換装置１１の２軸電圧指令値Ｖ_２ ^＊（ｔ）に次のような閉ループを施す。

ここで、初期値Ｖ_２ ^＊（０）は閉ループ制御を開始する直前のＶ_２ ^＊（ｔ）の値、Ｋ_ｆｒｅｑ（＞０）は積分ゲインである。Δω_０に乗じられるＶ_ｓ ^２の値は数１０を用いる。Ｖ_ｓ ^２の代替としてＥ_ｃｏ ^２を用いてもよい。 Here, it can be approximated as the following equation.

Therefore, the following closed loop is applied to the biaxial voltage command value V ₂ ^* (t) of the single-phase voltage type AC / DC converter 11 using the above equation.

Here, the initial value V ₂ ^* (0) is a value of V ₂ ^* (t) immediately before the start of the closed loop control, and K _freq (> 0) is an integral gain. Formula 10 is used as the value of V _s ² multiplied by Δω ₀ . E _co ² may be used as an alternative to V _s ² .

ここで、単相電圧型交直変換装置１１の出力の角周波数をω_ｉ（ｔ）とすると、

となる。数２から

となる。数２５を数２３に代入してω_ｉに関する微分方程式からω_ｉ（ｔ）を求めると次のようになる。

ここで、ω_ｉ（０）は閉ループ開始直前のω_ｉ（ｔ）の値である。

であるから、この閉ループ制御によって時間の経過とともに単相電圧型交直変換装置１１の出力の角周波数はω_ｓ＋Δω_０に近づくことになる。 Differentiating both sides of Equation 22 gives the following equation.

Here, when the angular frequency of the output of the single-phase voltage type AC / DC converter 11 is ω _i (t),

It becomes. From number 2

It becomes. Number 25 and seek the ω _{i (t)} from the differential equation for by substituting ω _i to the number 23 is as follows.

Here, ω _i (0) is the value of ω _i (t) immediately before the start of the closed loop.

Therefore, with this closed loop control, the angular frequency of the output of the single-phase voltage type AC / DC converter 11 approaches ω _s + Δω ₀ over time.

Further, the procedure [3] for paralleling the single-phase voltage type AC / DC converter 11 to the external single-phase AC voltage source 12 will be described. In the synchronous verification circuit 130, the voltage effective value V _i and the frequency ω _i of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11 are the voltage effective value V _s and the frequency ω _s of the external single-phase AC voltage source 12, respectively. When it is within a predetermined prescribed range as the center, the interconnection switch 15 is closed and the single-phase voltage type AC / DC converter 11 and the external single-phase AC voltage source 12 are arranged in parallel.

FIG. 3 is a diagram illustrating logic for paralleling the single-phase voltage type AC / DC converter 11 performed by the automatic synchronous parallel device 17 to the external single-phase AC voltage source 12. It is assumed that a parallel command (step S01) is issued when the interconnection switch 15 is in the open state (step S02). The automatic synchronous parallel device 17 starts the V ₁ ^* closed loop and the V ₂ ^* closed loop (steps S03 and S04). The automatic synchronous parallel device 17 confirms the following four conditions. | V _s −V _i (t) | ≦ ΔV _s (step S05). Here, ΔV _s represents an allowable amplitude difference, for example, about 5% of V _s . | Ω _s + Δω−ω _i (t) | ≦ Δω (step S06). Here, [Delta] [omega represents the tolerance of the angular frequency, for example, to be 1% of omega _s. V _U3 (t) calculated by the synchronization verification circuit 130 is greater than 0 (step S07). V _U4 (t) calculated by the synchronization verification circuit 130 is | V _U4 (t) | ≦ V _s · sin Δθ _i | (step S08). Here, Δθ _i represents an allowable phase difference, for example, about 5 degrees. After confirming that the above four conditions continue for the time T _detect (step S09), the automatic synchronous parallel device 17 _issues a command to close the interconnection switch 15 (step S10). The interconnection switch 15 is closed in response to the command (step S11). Thereafter, the automatic synchronous parallel device 17 ends the V ₁ ^* closed loop and the V ₂ ^* closed loop (steps S12 and S13).

Note that step S07 is equivalent to cos (ω _s t−θ _i (t))> 0. This is a condition for eliminating the possibility of being paralleled with a phase shifted by 180 ° under the condition of step S08.

  FIG. 4 is a diagram illustrating logic for disconnecting the single-phase voltage type AC / DC converter 11 performed by the automatic synchronous parallel device 17 from the external single-phase AC voltage source 12. Assume that a disconnection command (step S21) is issued when the interconnection switch 15 is closed (step S22). The automatic synchronous parallel device 17 issues a command to open the interconnection switch 15 (step S23). The interconnection switch 15 is opened in response to the command.

Example 1
FIG. 5 shows a one-axis voltage command value, a two-axis voltage command value, and a single-phase voltage type AC / DC when the automatic synchronous parallel device 17 parallels the single-phase voltage type AC / DC converter 11 with the external single-phase AC voltage source 12. It is the result of having simulated the single phase voltage waveform of the converter 11. FIG.

  The single-phase voltage type | mold AC / DC converter 11 shall be drive | operated by 200V and 50Hz before parallel. It is assumed that the external single-phase AC voltage source 12 is operated at 220 V and 54 Hz. At time 80 ms, the interconnection command (step S01) shown in FIG. Thereafter, the voltage waveform command value gradually increases from 200V and is constant at 240V (corresponding to the output voltage 220V). Along with this, the single-phase AC voltage amplitude value of the single-phase voltage type AC / DC converter 11 approaches the amplitude value of the AC voltage waveform of the external single-phase AC voltage source 12. The biaxial voltage command value also gradually increases from 0V and is constant at 41.3V. This voltage corresponds to the frequency 54.05 Hz of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11.

  As shown in FIG. 5, the magnitude and frequency of the output voltage of the single-phase voltage type AC / DC converter 11 gradually approach the voltage and frequency of the external single-phase AC voltage source 12, and these coincide with each other after approximately 150 ms. That is, the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter 11 is synchronized with the voltage waveform of the external single-phase AC voltage source 12 in about 150 ms.

(Example 2)
An experiment was conducted in which the automatic synchronous parallel device 17 paralleled the single-phase voltage type AC / DC converter 11 with the external single-phase AC voltage source 12. The single-phase voltage type AC / DC converter 11 is operated at 200 V and 50 Hz before parallel. The external single-phase AC voltage source 12 is operated at 240 V and 60 Hz. FIG. 6 shows that in this experiment, the single-phase voltage waveform of the single-phase voltage type AC / DC converter 11, the voltage waveform of the external single-phase AC voltage source 12, and the output current of the single-phase voltage type AC / DC converter 11 were measured before and after parallel. It is a result. FIG. 6A shows a waveform before paralleling, and FIG. 6B shows a waveform immediately before and immediately after paralleling.

  As shown in FIG. 6A, the single-phase voltage waveform of the single-phase voltage type AC / DC converter 11 and the voltage waveform of the external single-phase AC voltage source 12 are shifted before parallel. After the parallel command synchronizes the single-phase voltage waveform of the single-phase voltage type AC / DC converter 11 and the voltage waveform of the external single-phase AC voltage source 12 in parallel, before the parallel, the single-phase voltage type AC / DC converter 11 The single-phase voltage waveform and the voltage waveform of the external single-phase AC voltage source 12 match. In addition, although distortion has arisen in the output current of the single phase voltage type | mold AC / DC converter 11 after a parallel, this is overexcitation by having applied 240V to the 200V transformer installed in the input side of the external single phase alternating voltage source 12. For.

  Thus, the automatic synchronous parallel device 17 can parallel the single-phase voltage type AC / DC converter controlled to be a voltage source in parallel with the external single-phase AC voltage source.

11: Single-phase voltage type AC / DC converter 12: External single-phase AC voltage source 15: Linkage switch 17: Automatic synchronous parallel device 120: High-order command vector 130: Synchronization test circuit 133: Sampler 134: Delay circuit 135: Calculation Unit 136: detection unit 151: rotating coordinate conversion circuits 152A, 152B: low-pass filter 153: frequency difference cosine signal output terminal 154: frequency difference sine signal output terminals 161, 162, 163: circuit 180: voltage amplitude command value generation circuit 181: Voltage system subtractor 182: Voltage system integrator 183: Voltage system adder 190: Frequency command value generation circuit 191: Frequency system calculator 192: Frequency system integrator 193: Frequency system adder

Claims (5)

External single phase that is targeted for parallel operation by a single-phase voltage type AC / DC converter that performs autonomous parallel operation based on a single-axis voltage command value that adjusts the amplitude of the output single-phase AC voltage waveform and a two-axis voltage command value that adjusts the frequency A synchronous verification circuit that detects a value related to a frequency difference between the AC voltage source and the single-phase voltage type AC / DC converter, and a value related to a voltage effective value of the single-phase AC voltage source;
The single-phase voltage command value is generated to approximate the effective value of the single-phase AC voltage of the single-phase voltage type AC / DC converter to the effective value of the voltage of the external single-phase AC voltage source detected by the synchronous verification circuit, and the single-phase voltage is generated. Voltage amplitude command value generation circuit to be input to the type AC / DC converter,
Using the value related to the frequency difference detected by the synchronization verification circuit, the single-phase AC voltage frequency of the single-phase voltage type AC / DC converter is a frequency shifted by an arbitrary frequency value from the frequency of the external single-phase AC voltage source. A frequency command value generation circuit for generating a biaxial voltage command value and inputting it to the single-phase voltage type AC / DC converter;
An automatic synchronous parallel device. The voltage amplitude command value generation circuit includes:
A voltage system subtractor that subtracts a value related to a voltage effective value of a single-phase AC voltage waveform output by the single-phase voltage type AC / DC converter from a value related to a voltage effective value of the external single-phase AC voltage source detected by the synchronization verification circuit; ,
A voltage system integrator for integrating the value subtracted by the voltage system subtractor;
The single-axis voltage command is obtained by adding the initial value of the single-phase AC voltage of the single-phase voltage type AC / DC converter before the start of automatic parallel control with the external single-phase AC voltage source and the value integrated by the voltage system integrator. A voltage adder that generates a value;
The automatic synchronous parallel device according to claim 1, comprising: The frequency command value generation circuit includes:
Frequency system computing unit for adding a value related to the frequency difference detected by the synchronization verification circuit to a value obtained by multiplying the value related to the voltage effective value of the external single-phase AC voltage source detected by the synchronization verification circuit by the arbitrary frequency value When,
A frequency system integrator that integrates a value calculated by the frequency system calculator;
The biaxial voltage is obtained by adding the initial frequency of the single-phase AC voltage of the single-phase voltage type AC / DC converter before the start of automatic parallel control with the external single-phase AC voltage source and the value integrated by the frequency integrator. A frequency adder for generating a command value;
The automatic synchronous parallel device according to claim 1 or 2, characterized by comprising:   4. The automatic synchronous parallel device according to claim 2, wherein the value related to the voltage effective value is a square value of the voltage effective value. The synchronization verification circuit includes:
When the voltage effective value and frequency of the single-phase AC voltage waveform of the single-phase voltage type AC / DC converter are within a predetermined specified range centered on the voltage effective value and frequency of the single-phase AC voltage source, respectively, 5. The automatic synchronous parallel device according to claim 1, wherein a phase voltage type AC / DC converter and the external single-phase AC voltage source are paralleled. 6.

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