JP3173892B2 - Control device for voltage imbalance compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage imbalance using a power converter for improving a voltage imbalance caused by an unbalanced load connected to a power system or an impedance imbalance of a transmission line. The present invention relates to a control device for a balance compensator.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional control device of this kind, in which 31 is a power system, 32 is a transformer,
1 is a voltage imbalance compensator using a self-excited power converter to be controlled, 2 is a load, 3a and 3b are current transformers, 4 is a reference sine wave generation circuit, 5a and 5b are antiphase current detection circuits, 6
a and 6b are inverting amplifiers, 7a and 7b are subtractors, 8a and 8
b is a current regulator, 9 is an output voltage calculation circuit of the compensator 1,
Reference numeral 10 denotes a PWM pulse generation circuit. In this control device, a negative-phase current of the load 2 is detected, and a current for compensating the negative-phase current is injected into the system 31 by the power converter in the compensating device 1, thereby correcting the voltage imbalance.

More specifically, the operation of this control device will be described in detail. First, the currents (load currents) i _La , i _Lb , i _{Lc of the} load 2 are shown.
Is detected by the current transformer 3b, and based on these currents and the reference sine waves sin θ and cos θ (θ = ωt) synchronized with the system voltage generated by the reference sine wave generation circuit 4, the negative-phase current detection circuit 5b detects the load. Calculate the two-axis components (negative-sequence load current) I _L2d and I _L2q of the negative-sequence current in the rotating coordinate system. Next, these polarities are inverted by the inverting amplifiers 6a and 6b to _generate compensation current command values I _C2d ^* and I _C2q ^* .

On the other hand, currents (compensation currents) i _Ca , i _Cb , and i _{Cc of} the compensating device 1 detected by the other current transformer 3a are also similarly calculated by the anti-phase current detection circuit 5a. Compensation current actual values) I _C2d and I _C2q are calculated, and the deviation between these and the compensation current command values I _C2d ^* and I _C2q ^* is calculated by a subtractor 7a.
7b. The current regulators 8a and 8b perform an adjustment operation so that the above-mentioned deviation becomes zero, and control the compensation current.
U. The output voltage calculation circuit 9 calculates the three-phase output voltage of the compensator 1 based on the outputs of the current regulators 8a and 8b. The PWM pulse generation circuit 10 switches the compensator 1 to obtain the output voltage. A gate pulse to be applied to the device is generated.

Here, the negative phase current detection circuits 5a and 5b respectively obtain the two orthogonal axis components of the negative phase current in the rotating coordinate system by the following calculation. First, the three-phase current is divided into a positive-phase component and a negative-phase component and is represented by the following Equation 1. In Equation 1, I ₁ is the amplitude of the positive-phase current, φ ₁ is the phase angle of the positive-phase current, and I 1
₂ is the amplitude of the negative phase current, φ ₂ is the phase angle of the negative phase current, θ = ωt
It is.

[0006]

(Equation 1)

This is subjected to αβ conversion to obtain Expression 2, and Expression 2 is obtained by performing the inverse rotation dq conversion instead of the normal dq conversion.

[0008]

(Equation 2)

[0009]

(Equation 3)

By extracting a direct current component from these components through a low-pass filter, a negative-phase current d-axis component I _2d and a negative-phase current q-axis component I _2q represented by Expressions 4 and 5 are obtained.

[0011]

## EQU4 ## I _2d = I ₂ sin φ ₂

[0012]

## _EQU5 ## I _2q = I ₂ cos φ ₂

By the above operation, the negative phase current detection circuit 5a
Is _calculated from the compensation currents i _Ca , i _Cb , i _{Cc in the} negative phase compensation current I _C2d ,
I _C2q is obtained, and the anti-phase current detection circuit 5b obtains anti-phase load currents I _L2d and I _L2q from the load currents i _La , i _Lb and i _Lc . Note that an actual control device requires an active power control system for controlling the DC voltage of the self-excited power converter, and a reactive power control system is required when performing phase adjustment of the power system 31. However, FIG. 5 omits these illustrations, and shows only the control system of the reverse-phase power.

[0014]

In the above-mentioned conventional control device, the voltage imbalance generated due to the unbalanced load lower than the installation point of the voltage imbalance compensation device 1 can be compensated. There is a problem that a voltage imbalance generated due to an unbalanced load or an imbalance in system impedance which is higher than the setting point 1 cannot be compensated. In addition, the compensation device 1
If there is an unbalanced load in the upper and lower positions of the installation point, compensating for the negative-sequence current of the lower load may adversely promote voltage imbalance. The present invention has been made to solve the above problems, and an object of the present invention is to enable voltage imbalance to be effectively compensated in any system operation state regardless of the installation position of a compensator. An object of the present invention is to provide a control device for a voltage imbalance compensation device.

[0015]

In order to achieve the above object, a first aspect of the present invention detects a voltage imbalance of a power system, and calculates a compensation current command value and a compensation current actual value of a two-axis component orthogonal to a rotating coordinate system. Of the voltage imbalance compensator based on the output of this current regulator, and the power converter in the compensator compensates for the negative phase in the power system. A control device for injecting a current to correct the voltage imbalance detects quadrature two-axis components _EA2d and _EA2q of the opposite-phase voltages from the three-phase voltages of the system voltage,
From these values, E _A2 = √ (E _A2d ² + E _A2q ² ), sinψ ₂ = E _A2d / E _A2 , cos ₂ = E _A2q / E _A2 (E _A2 : _Negative phase voltage absolute value, ψ ₂ : _Negative phase) and reverse-phase voltage detecting circuit for calculating a voltage phase angle), the compensation voltage command value E a deviation between the reverse-phase voltage absolute value E _A2 and the negative-phase voltage deadband value as an input _C2
A voltage regulator for outputting ^* , and the sin 前 記₂ and cosψ ₂
From the compensation voltage command value E _C2 ^* and the system impedance value of the three-phase average value including the resistance component R and the reactance component X, a compensation current command value I _C2d ^* , I
_C2q ^* is _{calculated as follows} ^: I _C2d ^* = E _C2 ^* × (R sin ψ ₂ −X cos ψ ₂ ) / (R ² + X ² ), I _C2q ^* = E _C2 ^* × (X sin ψ ₂ + R cos ψ ₂ ) / (R ² + X ² ) And a current command value calculation circuit obtained by the following.

According to a second aspect, in the first aspect,
The negative-phase voltage detection circuit detects the negative-phase voltage from the three-phase line voltage of the system voltage. Further, a third invention according to the first or second invention, further comprising a circuit for detecting a negative-phase load current and calculating a compensation current, wherein a compensation current command value and a current command value calculation circuit for the negative-phase load current are provided. And a new compensation current command value for the current regulator is obtained by adding the compensation current command value for the negative-phase voltage output from the controller.

[0017]

In the first or second aspect of the invention, instead of detecting and compensating for the negative-phase current of the load, the negative-phase voltage is detected from the three-phase voltage of the system or the three-phase line voltage. Compensation current command value is calculated and PWM based on the output of current regulator
A compensation current is injected into the system by control to compensate for voltage imbalance. Further, in the third invention, the voltage imbalance is compensated for by using both the above-described negative phase voltage compensation and negative phase current compensation of the load. This makes it possible to effectively compensate for all unbalanced loads at the upper and lower positions of the compensating device installation point and voltage unbalance phenomena caused by system impedance imbalance regardless of the system operation state.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an embodiment of the first invention. The same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. Hereinafter, different portions will be mainly described. That is, in the present embodiment, the three-phase voltages e _Aa , e _Ab , and e _Ac of the system are detected by the instrument transformer 11, and are detected together with the reference sine waves sin θ, c
Based on the Osshita, signal Sinpusai ₂ indicating the phase angle of the reverse-phase voltage absolute value E _A2 and the negative phase voltage, and a negative-phase voltage detecting circuit 12 for calculating a cos _2.

Then, the negative phase voltage dead zone value set by the setter 13a is subtracted by the subtractor 7c into the negative phase voltage absolute value E _A2.
Is input to the voltage regulator 14, and the compensation voltage command value E _C2 ^{* of the} output and the sinψ ₂ ,
From the cos 演算₂ and the resistance R and the reactance X of the system impedance value of the three-phase average value set by the setting units 13b and 13c, the current command value calculation circuit 17 calculates the compensation current command values I _C2d ^* and I _C2q ^* . It is configured to calculate.

The negative-phase voltage absolute value E _A2 is input to a comparator 15, and the comparator 15 detects when the negative-phase voltage absolute value E _A2 becomes smaller than a predetermined value smaller than the negative-phase voltage dead zone value. A signal is output, and the output of the signal is stopped when the signal becomes larger than a predetermined value smaller than or equal to the dead zone value. The output signal of the comparator 15 is input to the timer 16. Timer 1
An output signal 6 changes the output signal when the above-mentioned state continues for a predetermined time or more, and performs zero hold and release of the output of the voltage regulator 14 by this signal.

Here, the negative-sequence voltage detection circuit 12 calculates the negative-sequence voltage absolute value E _A2 and the phase angle signal s of the negative-sequence voltage by the following calculation similar to the negative-sequence current detection calculation described in FIG.
inψ _2, determine the cosψ _2. First, the three-phase voltage is divided into a positive-phase component and a negative-phase component, and is represented by Expression 6. Incidentally, E _A1 positive phase voltage amplitude, [psi ₁ is the positive phase voltage phase angle, E _A2 reverse phase voltage amplitude (reverse-phase voltage absolute value) In Equation 6, [psi ₂ is a reverse-phase voltage phase angle. Next, dβ of αβ conversion and reverse rotation
Equation 7 is obtained by performing the conversion.

[0022]

(Equation 6)

[0023]

(Equation 7)

By extracting the DC component from these through the low-pass filter in the same manner as described above, the negative-phase voltage d-axis component E _A2d and the _negative- phase voltage q
The axial component E _A2q is obtained.

[0025]

[Equation 8] E _A2d = E _A2 sinψ ₂

[0026]

[Equation 9] E _A2q = E _A2 cosψ ₂

From the above, E _A2 , sin { ₂ , cos}
₂ can be obtained by the calculation of the following Expressions 10 to 12 by the anti-phase voltage detection circuit 12.

[0028]

[ _Equation 10] E _A2 = √ (E _A2d ² + E _A2q ² )

[0029]

[Equation 11] sinψ ₂ = E _A2d / E _A2

[0030]

[Number 12] cosψ ₂ = E _A2q / E _A2

On the other hand, the current command value calculation circuit 17 calculates the compensation voltage command value E _C2 ^* from the voltage regulator 14 and the above sinψ ₂ , c
Ospusai ₂ and based on the resistance component R, reactance X of the system impedance values, the following equation 13, the compensation current command value I _C2d ^* according to Equation 14, a circuit for calculating the I _C2q ^*.

[0032]

I _C2d ^* = E _C2 ^* × (R sin ψ ₂ −X cos ψ ₂ ) / (R ² + X ² )

[0033]

I _C2q ^* = E _C2 ^* × (X sin ψ ₂ + R cos ₂ ) / (R ² + X ² )

Next, the meaning of these formulas will be described with reference to the system model diagram of FIG. Note that the suffix "" in the code in FIG. 2 indicates that it is a complex vector representation. The phase voltage and current at the installation point of the voltage imbalance compensator 1 are represented by Expressions 15 and 16.

[0035]

(Equation 15)

[0036]

(Equation 16)

The respective voltages and currents are converted into symmetric coordinates by the following equation (17).
Or as shown in Equation 21. Here, if the three-phase AC power supply of the system is an ideal power supply, e ' _S0 = 0, e' _S2 = 0, and if there is no zero-phase current, i ' _S0 = 0, i' _L0 =
0, i ' _C0 = 0.

[0038]

[Equation 17]

[0039]

(Equation 18)

[0040]

[Equation 19]

[0041]

(Equation 20)

[0042]

(Equation 21)

Expressions 17 to 21 are based on Expression 22. In this equation 22, a = − ＋+ j√3 / 2, and a ² = − ／ − j√3 / 2.

[0044]

(Equation 22)

From the above equations, Equation 23 is established.

[0046]

(Equation 23)

Assuming that only the negative-sequence current is injected as the compensating current, the negative-sequence voltage is compensated. If i ′ _C1 = 0, Equation 24 is obtained.

[0048]

E ′ _A2 = − (1/3) × {(Za + aZb + a ² Zc) i ′ _L1 + (Za + Zb + Zc) (i ′ _L2 + i ′ _C2 )}

When the negative-phase voltage before compensation is expressed by Expression 25 and the compensation voltage by the compensating device 1 is expressed by Expression 26, the voltage e ′ _A2 after compensation by Expression 24 is expressed by Expression 27.

[0050]

E ′ _B2 = − (１ ／) × {(Za + aZb + a ² Zc) i ′ _L1 + (Za + Zb + Zc) i ′ _L2 }

[0051]

E ′ _C2 = − (１ ／) × (Za + Zb + Zc) i ′ _C2

[0052]

[Equation 27] e ′ _A2 = e ′ _B2 + e ′ _C2

[0053] Here, placing the compensation voltage e _'C2 as in Equation 28, controlled to be a voltage and reverse after compensating the compensation voltage as shown in the vector diagram of FIG. 3, adjusting the gain K _C By doing so, the reverse phase voltage can be compensated.
Thus, the compensated voltage e ′ _A2 is as shown in Expression 29.

[0054]

[Equation 28] e ′ _C2 = −K _C × e ′ _A2 (K _C ≧ 0)

[0055]

[Equation 29] e ′ _A2 = e ′ _B2 / (1 + K _C )

Note that the compensation current i ' _C2 is as shown in Expression 30, where Za = Ra + jXa, Zb = Rb + jXb, Zc
= Rc + jXc, R = (Ra + Rb + Rc) / 3, X =
If (Xa + Xb + Xc) / 3, Equation 31 is obtained.

[0057]

I ′ _C2 = 3K _C × e ′ _A2 / (Za + Zb + Zc)

[0058]

I ′ _C2 = K _C × e ′ _A2 / (R + jX)

On the other hand, since i ′ _C2 and e ′ _A2 can be expressed by Expressions 32 and 33, respectively, Expression 34 is obtained.

[0060]

[ _Expression 32] i ′ _C2 = I _C2q + jI _C2d

[0061]

[ _Equation 33] e ′ _A2 = E _A2q + jE _A2d

[0062]

(Equation 34)

As described above, in FIG. 1, the negative-phase voltage command value of the output of the voltage regulator 14 for adjusting the absolute value of the negative-phase voltage is represented by E
_C2 ^* = Position and K _C E _A2, negative sequence current command value I _C2d ^* by the current command value calculating circuit 17 according to equation 34, assuming that performs calculation of I _C2q ^*, Equation 35 is obtained.

[0064]

(Equation 35)

In the first embodiment of the present invention, the control is performed by detecting the three-phase voltage of the system voltage. However, it is also possible to detect and control the three-phase line voltage instead of the phase voltage. is there. The second invention is based on this idea, and the control device of the embodiment _converts the three-phase voltages e _Aa , e _Ab , and e _Ac of the system voltage in FIG. 1 into three-phase line voltages e _Aab , e _Abc. , E _Aca
To also configured by replacing the negative-phase voltage absolute value E _A2 of the output of the negative-phase voltage detecting circuit 12 to E _AD2. In this case, reverse-phase voltage detecting circuit 12 is carried out by calculation substantially similar to the following operation described above, the reverse-phase voltage absolute value E _AD2 and the phase angle signal Sinpusai ₂ of the line voltage, the operation of the cos ₂ .

That is, the three-phase voltage is divided into a positive-phase component and a negative-phase component, and is represented by Expression 36. Incidentally, the E _AD1 in Equation 36 the positive phase voltage amplitude, [psi ₁ is the positive phase voltage phase angle, E
_AD2 reverse phase voltage amplitude (reverse-phase voltage absolute value), [psi ₂ is a reverse-phase voltage phase angle. Next, the αβ conversion and the inverse rotation dq conversion are performed to obtain Expression 37.

[0067]

[Equation 36]

[0068]

(37)

By extracting the DC component from these through the low-pass filter in the same manner as described above, Equations 38 and 3 are obtained.
A negative-phase voltage d-axis component E _AD2d and a _negative- phase voltage q-axis component E _AD2q represented by 9 are obtained.

[0070]

[Number 38] E _AD2d = E _AD2 sinψ ₂

[0071]

[Number 39] E _AD2q = E _AD2 cosψ ₂

From the above, E _AD2 , sinψ ₂ , cosψ ₂
Can be calculated by the following equations 40 to 42 by the negative-sequence voltage detection circuit 12.

[0073]

[ _Equation 40] E _AD2 = √ (E _AD2d ² + E _AD2q ² )

[0074]

[Equation 41] sinψ ₂ = E _AD2d / E _AD2

[0075]

[ _Equation 42] _{cosψ 2} = E _AD2q / E _AD2

When the control is performed by detecting the line voltage as in this embodiment, the current command value calculation circuit 17 calculates the compensation current command values I _C2d ^* and I _{C
Calculate C2q} ^* . In these equations, A, B
Are represented by Equations 45 and 46, respectively.

[0077]

[Number 43] _{^{I C2d * = E C2 * ×}} (Asinψ 2 -Bcosψ 2) / (A 2 + B 2)

[0078]

I _C2q ^* = E _C2 ^* × (B sin ψ ₂ + A cos ψ ₂ ) / (A ² + B ² )

[0079]

A = √3R / 2 + X / 2

[0080]

B = √3X / 2−R / 2

Hereinafter, the derivation process of these equations will be described.
First, in FIG. 2, the line voltage and the phase current at the installation point of the compensator 1 are represented by Expressions 47 and 48.

[0082]

[Equation 47]

[0083]

[Equation 48]

The respective voltages and currents are converted into symmetric coordinates by the following equation (49).
Or as shown in Equation 53. Here, assuming that the three-phase AC power supply of the system is an ideal power supply, e ′ _SD0 = 0, e ′ _SD2 = 0,
Assuming that there is no zero-phase current, i ′ _S0 = 0, i ′ _L0 =
0, i ' _C0 = 0.

[0085]

[Equation 49]

[0086]

[Equation 50]

[0087]

(Equation 51)

[0088]

(Equation 52)

[0089]

(Equation 53)

Expressions 49 to 53 are based on Expression 54. In this equation 54, a = − ／ + j√3 / 2 and a ² = − ／ − j√3 / 2.

[0091]

(Equation 54)

From the above equations, Equation 55 is established.

[0093]

[Equation 55]

Assuming that only the negative-sequence current is injected as the compensation current, the negative-sequence voltage is compensated. If i ′ _C1 = 0, Equation 56 is obtained.

[0095]

Equation 56] _{e 'AD2 = - {(1} -a) / 3} × {(Za + aZb + a 2 Zc) i' L1 + (Z a + Zb + Zc) (i 'L2 + i' C2)}

When the negative-phase voltage before compensation is expressed by Expression 57 and the compensation voltage by the compensator 1 is expressed by Expression 58, the voltage e ′ _AD2 after compensation by Expression 56 is expressed by Expression 59.

[0097]

Equation 57] _{e 'BD2 = - {(1} -a) / 3} × {(Za + aZb + a 2 Zc) i' L1 + (Z a + Zb + Zc) i 'L2}

[0098]

E ′ _CD2 = − {(1-a) / 3}) × (Za + Zb + Zc) i ′ _C2

[0099]

[ _Equation 59] e ′ _AD2 = e ′ _BD2 + e ′ _CD2

[0100] Here, placing the compensation voltage e _'CD2 as Formula 60, controlled to be a voltage and reverse after compensating the compensation voltage as shown in the vector diagram of FIG. 3, adjusting the gain K _C By doing so, the reverse phase voltage can be compensated. Thus, the compensated voltage e ′ _AD2 is as shown in Expression 61.

[0101]

E ′ _CD2 = −K _C × e ′ _AD2 (K _C ≧ 0)

[0102]

E ′ _AD2 = e ′ _BD2 / (1 + K _C )

Note that the compensation current i ′ _C2 is as shown in Expression 62, where Za = Ra + jXa, Zb = Rb + jXb, Zc
= Rc + jXc, R = (Ra + Rb + Rc) / 3, X =
If (Xa + Xb + Xc) / 3, Equation 63 is obtained.

[0104]

I ′ _C2 = 3K _C × e ′ _AD2 / {(1−a) × (Za + Zb + Zc)}

[0105]

I ′ _C2 = K _C × e ′ _AD2 / {(1−a) × (R + jX)}

On the other hand, since i ′ _C2 , e ′ _AD2 , 1−a can be expressed by Equations 64 to 66, A ′
= √3R / 2 + X / 2, B = √3X / 2−R / 2, Equation 67 is obtained.

[0107]

I ′ _C2 = I _C2q + jI _C2d

[0108]

[ _Equation 65] e ′ _AD2 = E _AD2q + jE _AD2d

[0109]

1−a = 1 − (− ／ + j√3 / 2) = √3 (√3 / 2−j / 2)

[0110]

[Equation 67]

As described above, in FIG. 1, the negative-phase voltage command value of the output of the voltage regulator 14 for adjusting the absolute value of the negative-phase voltage is represented by E
_C2 ^* = Position and K _C E _AD2 / √3, the compensation current command value I _C2d ^* by the current command value calculating circuit 17 according to equation 67, I _C2q ^*
Equation 68 is obtained if the above operation is performed.

[0112]

[Equation 68]

Next, FIG. 4 shows an embodiment of the third invention. In this embodiment, a negative phase voltage detecting circuit 12, a voltage regulator 14, a current command value calculating circuit 17 and the like for detecting a negative phase voltage of a system voltage similar to that of FIG. 1 and calculating a compensation current command value are provided. Also, as in the prior art (see FIG. 5), a negative-phase current detection circuit 5b for detecting a negative-phase load current and calculating a compensation current, and inverting amplifiers 6a and 6b are also provided.
The compensation current command values calculated by these two circuits are added by the adders 18a and 18b, and a value obtained by the addition is used as a new compensation current command value for the current regulators 8a and 8b.

A limiter 19 is provided on the output side of the inverting amplifiers 6a and 6b to determine the capacity distribution between the negative-sequence load current compensation and the negative-sequence voltage compensation. It is designed to be applied. The limiter 19 for determining the capacity distribution between the negative-phase load current compensation and the negative-phase voltage compensation is provided not on the negative-phase load current compensation circuit but on the current command value side of the negative-phase voltage compensation circuit, as shown in FIG. Alternatively, it may be provided on the current command value side of both the negative phase load current compensating circuit and the negative phase voltage compensating circuit.

[0115]

As described above, in the first or second invention, a compensation current command value is calculated by detecting a reverse phase voltage from a three-phase voltage or a three-phase line voltage of a system. Third
In the invention of the present application, the compensation current command value is calculated by using both the opposite-phase voltage compensation and the opposite-phase current compensation of the load, and the compensation current is injected into the system by the compensator based on the output of the current regulator to cause the voltage imbalance. Is to compensate. This makes it possible to effectively compensate for all unbalanced loads at the upper and lower positions of the compensator installation point and all voltage unbalance phenomena caused by system impedance imbalance regardless of the system operation state.

Further, when both the negative-sequence voltage compensation and the negative-sequence current compensation of the load are used at the same time, the compensating capacity of the two is distributed by the limiter as necessary, thereby causing the unbalanced load of the higher system and the imbalance of the system impedance. It is possible to effectively compensate for the voltage imbalance that occurs and the voltage imbalance caused by the lower system unbalanced load according to the system operation state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the first invention.

FIG. 2 is a system model diagram to which each embodiment is applied.

FIG. 3 is a vector diagram for explaining a principle of compensating an unbalanced voltage in each embodiment.

FIG. 4 is a block diagram showing a configuration of an example of the third invention.

FIG. 5 is a block diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage imbalance compensator 2 Load 3a, 3b Current transformer 4 Reference sine wave generation circuit 5a, 5b Negative phase current detection circuit 6a, 6b Inverting amplifier 7a, 7b, 7c Subtractor 8a, 8b Current regulator 9 Output voltage calculation Circuit 10 PWM pulse generation circuit 11 Instrument transformer 12 Negative phase voltage detection circuit 13a, 13b, 13c Setting device 14 Voltage regulator 15 Comparator 16 Timer 17 Current command value calculation circuit 18a, 18b Adder 19 Limiter 31 Power system 32 Transformer vessel

Continuation of the front page (72) Inventor Toshihiro Nakamura 20-1, Kita-Sanzan, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Prefecture Chubu Electric Power Co., Inc. Technology Development Division Electric Power Technology Research Laboratory (72) Inventor Shigeo Konishi Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Kenji Baba 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, Japan Fuji Electric Co., Ltd. (72) Inventor Takehiko Kojima Kawasaki, Kanagawa Prefecture Fuji Electric Co., Ltd. (1-1) Tanabe Nitta, Ichikawasaki-ku (56) References JP-A-1-97138 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 3 / 26 G05F 1/44

Claims (5)

(57) [Claims] The present invention detects a voltage imbalance in a power system and operates a current controller to reduce a deviation between a compensation current command value and a compensation current actual value of two orthogonal components of a rotating coordinate system to zero. A controller for calculating the output voltage of the voltage imbalance compensator based on the output of the controller and injecting a negative-sequence compensation current into a power system by a power converter in the compensator to correct the voltage imbalance. From the three-phase voltage of the system voltage, orthogonal two-axis components E _A2d and E _A2q of the opposite phase voltage are detected, and from these values, E _A2 = √ (E _A2d ² + E _A2q ² ), sinψ ₂ = E _A2d / E _A2 , _{cosψ 2} = E _A2q / E _A2 (E _A2 : _Negative phase voltage absolute value, ψ ₂ : _Negative phase voltage phase angle) and a negative phase voltage absolute value E _A2 a voltage regulator for outputting a compensation voltage command value E _C2 ^* a deviation between the phase voltage deadband value as an input The sinψ _2, and cos _2, the compensation voltage command value E _C2
^*, And compensation current command values I _C2d ^* and I _C2q ^* for the current regulator from the system impedance value of the three-phase average value including the resistance component R and the reactance component X, I _C2d ^* = E _C2 ^* × ( _{Rsinψ 2 -Xcosψ 2) / (R} 2 + X 2), I C2q * = E C2 * × (Xsinψ 2 + Rcosψ 2) / (R 2 + X 2) becomes the current command value calculating circuit for obtaining by calculation, further comprising a A control device for a voltage imbalance compensation device, comprising: 2. A current controller which detects a voltage imbalance of a power system and operates a current regulator so as to make a deviation between a compensation current command value and an actual compensation current value of two orthogonal components of a rotating coordinate system zero. A controller for calculating the output voltage of the voltage imbalance compensator based on the output of the controller and injecting a negative-sequence compensation current into a power system by a power converter in the compensator to correct the voltage imbalance. From the three-phase line voltage of the system voltage, quadrature two-axis components E _AD2d and E _AD2q of the opposite phase voltages are detected, and from these values, E _AD2 = √ (E _AD2d ² + E _AD2q ² ), sinψ ₂ = E _AD2d / E _AD2 , _{cosψ 2} = E _AD2q / E _AD2 (E _AD2 : _Negative -phase voltage absolute value, ψ ₂ : _Negative -phase voltage phase angle) and the negative-phase voltage absolute value E _AD2 to output the compensation voltage command value E _C2 ^* as inputs a deviation between reverse phase voltage deadband value and A voltage regulator, the Sinpusai _2, and cos _2, the compensation voltage command value E _C2
^*, And compensation current command values I _C2d ^* and I _C2q ^* for the current regulator from the system impedance value of the three-phase average value including the resistance component R and the reactance component X, I _C2d ^* = E _C2 ^* × ( _{Asinψ 2 -Bcosψ 2) / (A} 2 + B 2), I C2q * = E C2 * × (Bsinψ 2 + Acosψ 2) / (A 2 + B 2) ( where, A = √3R / 2 + X / 2, B = √3X / 2-
R / 2) a control circuit for a voltage imbalance compensation device, comprising: a current command value calculation circuit obtained by calculation. 3. A signal is output upon detecting that the negative phase voltage absolute value E _A2 or E _AD2 has become smaller than a predetermined value smaller than the negative phase voltage dead zone value, and a signal is output, and is smaller than or equal to the negative phase voltage dead zone value. 3. The voltage imbalance compensation according to claim 1, further comprising a comparator for stopping the output of the signal when the voltage exceeds a predetermined value, and performing zero hold and release of the output of the voltage regulator based on the output signal of the comparator. Equipment control device. 4. The control device for a voltage imbalance compensator according to claim 1, 2 or 3, wherein a three-phase current of a load connected to a power system and two orthogonal components I _L2d and I _{L2q of a} negative-phase current _thereof. Current detection circuit for detecting the phase difference, and a compensation current command value for a negative phase load current obtained by inverting the values of these orthogonal two-axis components I _L2d and I _L2q and a negative phase output from the current command value calculation circuit. Means for adding a compensation current command value with respect to the voltage, respectively, and using the addition result as a new compensation current command value for the current regulator. 5. A method according to claim 1, wherein at least one of a compensation current command value for the negative-sequence load current and a compensation current command value for the negative-sequence voltage is limited by a limiter, and capacity distribution for the negative-sequence load current compensation and the negative-sequence voltage compensation is performed. 5. The control device of the voltage imbalance compensation device according to 4.