JPH11155236A - Method and system for compensating reactive power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a voltage compensating work shared in harmony between a reactive power compensating device installed at the load side of the system, in which a tap changing type voltage regulator is provided at the power supply side and the voltage regulator, without transmitting or receiving control signals between the two devices. SOLUTION: This method is composed of a reactive power compensating device 3, which is connected to a system, controlling means 6, 7, 8, which controls the reactive current or reactive power of the reactive power compensating device, in such a way as to reduce the deviation of the detected value from a command value of the system voltage, and a correcting means 21, which corrects the command value of the system voltage in such a way as to gradually reduce the deviation of the detected value from a set value of the reactive current. For the change in the system voltage, an installation point voltage is immediately made to agree with the command value with the reactive power compensating device 3 at an initial stage. Thereafter, the installation point voltage is gradually made to depart from the initial command value to have the output of the reactive power compensating device 3 reduced. The voltage fluctuations caused by this operation makes a voltage regulator 12 actuate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive power compensation method and system for compensating for voltage fluctuations in a power system.

[0002]

2. Description of the Related Art A reactive power compensation system is a system for detecting a voltage of a power system and controlling the reactive power injected from the reactive power compensator into the power system so that the voltage matches a command value. Here, the principle of voltage compensation by reactive power compensation will be described with reference to FIG. In FIG. 2, 1 is an AC power supply, 2 is a distribution line impedance, R is a resistance,
X represents a reactor, and 3 represents a reactive power compensator. Vs indicates an AC power supply voltage, Vr indicates a system voltage at an installation point to which the reactive power compensator 3 is connected (hereinafter, referred to as an installation point voltage), and Iq indicates a reactive current flowing from the system to the reactive power compensator 3. In addition, Iq assumes that the delay is positive. In FIG. 2, if the resistance R is sufficiently smaller than the reactor X, the equation (1) holds.

Vr = Vs−XIq (1) Here, the setting point voltage Vr accompanying the minute change ΔIq of Iq
Is a change amount of ΔVr, Expression (2) is satisfied, and Expression (3) is satisfied from Expressions (1) and (2).

Vr + △ Vr = Vs−X (Iq + △ Iq) (2) ΔVr = −X △ Iq (3) Therefore, when ΔIq> 0, that is, the output of the reactive current changes to the delay side △ Vr <0,
The installation point voltage Vr decreases. Conversely, when △ Iq <0,
When the output of the reactive current changes to the leading side, ΔVr>
0, and the installation point voltage Vr increases. Thus, by adjusting the reactive current Iq of the reactive power compensator 3, the installation point voltage Vr can be controlled. In the above, the principle of the voltage compensation by the reactive current Iq has been described. However, if Q = Vr · Iq, the voltage compensation by the reactive power Q can be similarly described.

A reactive power compensating system that suppresses voltage fluctuations in the power system by controlling the reactive power of the power system by applying such a principle has been disclosed in, for example, Japanese Patent Application Laid-Open No.
What is described in -317523 is known.
According to this, the reactive power compensator is connected to a position near the load side of the distribution line, and the voltage of the distribution line at the connection point is detected,
The reactive current command value is determined according to the deviation so that the detected value matches the command value, the reactive current of the reactive power compensator is controlled based on the command value, and the voltage fluctuation of the distribution line is determined. It is trying to suppress. Further, according to the publication, in addition to the reactive power compensating device, a voltage regulator of a winding tap switching type is provided on the power supply side of the distribution line, and this and the reactive power compensating device cooperate to provide It has been proposed to suppress voltage fluctuations.

That is, the voltage compensation by the reactive power compensator has a high response, but in order to suppress a large voltage fluctuation, the capacity of the device becomes too large and is not economical. Further, it is not economical that the voltage compensation by the reactive power compensator continues for a long time. Therefore, the reactive power of the reactive power compensator is detected, and when the integrated value of the reactive power exceeds the set value, the tap of the voltage regulator is switched,
The voltage of the distribution line is compensated by a voltage regulator close to the power supply side, thereby reducing the sharing of the reactive voltage compensator and making it possible to reduce the device capacity and output.

[0007]

However, according to the above-mentioned prior art, in order to coordinate the system voltage compensation between the reactive power compensator and the voltage regulator, the output reactive power of the reactive power compensator must be reduced. It is necessary to transmit a control signal such as a detected value or its integral value, or a winding tap switching command from the reactive power compensator to the voltage regulator.

The characteristics of the voltage compensation by the voltage regulator and the characteristics of the voltage compensation by the reactive power compensator are shown in FIGS.
There is a difference as shown in FIG. That is, as shown in FIG. 3, according to the voltage regulator, the voltage on the load side from the installation point is compensated, but the voltage on the power supply side from the installation point cannot be compensated. On the other hand, as shown in FIG. 4, according to the reactive power compensator, as the distance from the power source increases, that is, as the length of the distribution line from the power source to the installation point increases, the compensation width of the voltage fluctuation increases. Therefore, the compensation effect is higher when the voltage regulator is installed on the power supply side of the distribution line, and the compensation effect is higher when the reactive power compensator is connected to a position closer to the load side of the distribution line. As a result, when the voltage regulator and the reactive power compensator are respectively installed at locations where optimal compensation effects can be obtained, the distance between them may be, for example, about several km or more.

[0009] As described above, when an attempt is made to make arrangements at an optimum position by making use of the features of the respective devices, the distance between the reactive power compensator and the voltage regulator becomes longer, and the voltage adjustment from the reactive power compensator to the voltage regulator. In order to send a control signal to the device, signal transmission by wire communication or wireless communication is required, which causes the following problems.

1) When a transmission error occurs in a control signal due to the influence of noise or the like, a voltage fluctuation is increased by causing a malfunction of the device, or when a wired communication is performed, a voltage adjustment is performed when a signal line is cut. The reliability of the voltage compensation operation is lacking, for example, the device stops operating. 2) Since a communication device and a communication path are required, the equipment configuration becomes complicated and the equipment cost increases.

In addition, if there is an existing voltage regulator, the voltage regulator is modified so as to receive a signal from the reactive power compensator, or a new voltage regulator capable of receiving a signal from the reactive power compensator is used. Need to be replaced
There is also a problem that the equipment cost increases.

The problem to be solved by the present invention has been made in view of the above circumstances, and a reactive power compensator installed on a load side of a system in which a tap-switching type voltage regulator is installed on a power supply side. It is an object of the present invention to provide a reactive power compensation method and system capable of cooperatively performing voltage compensation sharing between control signals without transmitting and receiving control signals between the control device and the voltage regulator.

[0013]

As a means for solving the above-mentioned problems, the present invention relates to an output of a reactive current or a reactive power of a reactive power compensator connected to a system in order to adjust a detected value of a system voltage to a command value. Is controlled, the command value of the system voltage is corrected so that the detected value of the reactive current or the physical quantity corresponding to the detected value gradually approaches the set value.

Here, as the physical quantity corresponding to the detected value of the reactive current, a physical quantity having a strong correlation with the reactive current, such as a detected value of the output reactive power or its command value, a command value of the output reactive current, etc. can be applied. .

The term "gradually increasing" the detected value of the reactive current to gradually approach the set value is for cooperating with the operating characteristics of the tap switching device of the voltage regulator. That is, the tap switching device of the voltage regulator monitors the secondary voltage (load-side system voltage) of the voltage regulator, the secondary voltage fluctuates beyond a certain dead band width, and the fluctuation is set to a set time limit. , The taps are switched in a direction to compensate for the fluctuation. Therefore, in consideration of the dead zone width and the operation time limit related to the tap switching, the degree and time of “gradually” the detection value of the reactive current gradually approaches the set value are determined.

That is, according to the above solution, when the system voltage greatly fluctuates due to a load change, the reactive power compensator promptly controls the output of the reactive current so that the system voltage at the connection point matches the command value. Works. In this state, the reactive power compensator continuously outputs the reactive current necessary to suppress the voltage fluctuation. However, according to the present invention, when the detected value of the reactive power is larger (or smaller) than the set value, the command value of the system voltage is corrected to be higher (or lower) accordingly, and the detected value of the reactive power is corrected. Is corrected to match the set value. Accordingly, if the set value of the reactive power is set to a preferable reactive current output value (for example, 0) of the reactive power compensator in the steady state, the command value of the system voltage is gradually corrected accordingly, and the connection point System voltage gradually deviates from the initial command value, and the voltage fluctuation at that point increases. Then, due to the voltage fluctuation, the tap switching device of the voltage regulator installed near the power supply side operates, and the voltage regulator caused by the decrease in the output of the reactive power compensator is compensated by the voltage regulator. As a result, the voltage compensation operation by the reactive power compensator is constantly suppressed to a short time,
The compensation amount can be suppressed to a value corresponding to the capacity, and the excess can be shared by the voltage regulator. In the above operation process, since the reactive power compensator and the voltage regulator are independently controlled, there is no need to transmit and receive control signals between the reactive power compensator and the voltage regulator.

Also, the reactive power compensation system of the present invention comprises:
A reactive power compensating device connected to a grid, and control means for controlling a reactive current or reactive power of the reactive power compensating device so as to reduce a deviation between a detected value of a system voltage and a command value; Can be realized by providing a correction means for correcting the command value of the system voltage so as to reduce the deviation between the set value and the detected value of the reactive current or the physical quantity corresponding to the detected value.

In this case, the correction means corrects the command value of the system voltage so as to gradually reduce the deviation based on the detected value of the reactive current or the deviation between the physical value corresponding to the detected value and the set value. Is preferred. Specifically, integrating means for integrating the detected value of the reactive current or the deviation between the set value and the physical value corresponding to the detected value, and adding means for adding the output of the integrating circuit to the command value of the system voltage. It can be provided and configured. Alternatively, comparing means for outputting a constant value when a detected value of a reactive current or a deviation between a physical quantity corresponding to the detected value and a set value exceeds a preset threshold value, and integrating the output of the comparing means. And integrating means for adding the output of the integrating means to the command value of the system voltage. Preferably, a limiter circuit for limiting the magnitude of the command value of the system voltage after the correction is provided, and the integration operation of the integration means is stopped when the limiter circuit operates.

Further, there is provided abnormality determination means for outputting an abnormality signal when the corrected command value of the system voltage exceeds a predetermined determination reference value, and based on the abnormality signal, a detection value of the reactive current or the abnormality detection signal is output. It is preferable to change the set value relating to the physical quantity corresponding to the detected value to a large value. In other words, if the voltage regulator does not operate due to some kind of failure, the corrected command value will continue to increase, and based on this, it is possible to determine the abnormality of the voltage regulator, so that the reactive power compensation device Can be greatly changed, and the voltage compensation operation by this can be sufficiently exhibited according to the device capacity.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the reactive power compensation system of the present invention. In the figure, a reactive power compensator 3 is connected to a position close to a load side of the distribution line 4 connected to the AC power supply 1 and away from the power supply side, and a voltage regulator 12 is connected to a position close to the power supply side of the distribution line 4. Have been. In the drawing, reference numeral 2 denotes the impedance of the distribution line 4 as in FIG. 2 and includes a resistance R and a reactance X. The voltage regulator 12 detects a system voltage at the load side end of the voltage regulator 12 by a winding tap switching device (not shown), and the detected voltage exceeds an upper / lower limit set value having a dead zone and a predetermined time period. , The tap is switched in the step-up or step-down direction. As the reactive power compensator 3, an inverter formed using a semiconductor switch element is applied.

Here, the configuration of the control device of the reactive power compensator 3 will be described. The system voltage (installation point voltage) at the position where the reactive power compensator 3 is connected is detected by the voltage detection circuit 17 via the voltage sensor 16. The detected value V of the installation point voltage is input to the subtractor 6, where a deviation ΔV from a later-described installation point voltage command value V * is obtained. The command value V * is input to the subtractor 6 via a limiter circuit 24 described later. The deviation ΔV output from the subtractor 6 is input to the voltage control circuit 7, where the reactive current command value iqref for reducing the deviation ΔV is calculated and output to the current control circuit 8. The current control circuit 8 performs PWM so that the reactive current corresponding to the reactive current command value iqref input from the voltage control circuit 7 is output from the reactive power compensator 3.
A control signal is output to the control circuit 9. At this time, the current control circuit 8 performs feedback control based on the detected value i of the output current detected by the current sensor 10 provided at the output terminal of the reactive power compensator 3. PWM control circuit 9
Generates a gate pulse signal of the inverter in accordance with the control signal output from the current control circuit 8 and outputs the signal to the reactive power compensator 3. Thus, the reactive power compensator 3
Sets the voltage control circuit so that the voltage deviation ΔV between the detected value V of the installation point voltage and its command value V * is set to 0, that is, the detected value V of the installation point voltage is made to coincide with the command value V *. 7 and a current control circuit 8 to control the reactive power output.

Next, a configuration according to a characteristic portion of the present invention will be described. In the present embodiment, a reactive current detection circuit 18, a reactive current steady-state command value setting circuit 19, and a voltage command correction circuit 21 are provided, and the reactive current of the reactive power compensator 3 is detected.
The feature is that the command value V * of the installation point voltage is increased or decreased by correction so that the detected value of the reactive current approaches the steady-state command value iq * of the reactive current.

That is, in the reactive current steady command value setting circuit 19, the reactive current steady command value iq * is set as the value of the reactive current to be constantly compensated by the reactive power compensator 3. That is, the command value of the reactive current in a steady state after a sufficient time has elapsed since a certain voltage fluctuation occurred,
iq * is normally set to “0”. Reactive current detection circuit 1
8 fetches the detected value of the output current i of the reactive power compensator 3 from the current sensor 10 and the detected value V of the installation point voltage of the reactive power compensator 3 from the voltage sensor 16 and calculates the reactive current included in the output current i. The detection value iq is obtained. Then, the difference e between the detected value iq of the reactive current and the steady-state command value iq * is calculated by the subtractor 20 and output to the voltage command correction circuit 21.

The voltage command correction circuit 21 receives the deviation e and calculates a voltage command V * such that the deviation e gradually approaches zero. That is, the deviation e between iq and iq * gradually becomes zero.
Means that iq asymptotically approaches iq * over time, and coincides when it reaches a steady state. For example, when iq * = 0, the voltage command V * is calculated so that iq gradually approaches 0. This is iq
When the output is advancing, iq is decreased so as to lower the voltage command V *.
Is a delayed output, the calculation may be performed so as to increase the voltage command V *. That is, the voltage command correction value calculation circuit 22 calculates a correction value ΔV * for correcting the voltage command reference value V ₀ * so that the deviation e gradually approaches 0, and the adder 23 calculates the voltage command reference value. It is added to V ₀ * to generate a voltage command value V *. The command value V * of the voltage is input to the above-described subtractor 6 via the limiter circuit 24.
The limiter circuit 24 limits the command value V * to a predetermined value. Details of the configuration and operation of the voltage command correction circuit 21 will be described later.

As described above, the reactive current detection circuit 18,
The reactive current steady-state command value setting circuit 19 and the voltage command correction circuit 21 are feedback control circuits for the reactive current steady-state output of the reactive power compensator 3. By setting the control time of the reactive current steady-state output control in cooperation with the operation time of the voltage regulator 12, the output of the reactive power compensator 3 is large and long without transmitting a signal to the voltage regulator 12. When continuing, the voltage regulator 12 can be assigned voltage compensation. This operation will be described with reference to FIG.

FIG. 5 shows how voltage is compensated by the reactive power compensating device 3 and the voltage adjusting device 12 in the embodiment of FIG. 1 with time on the horizontal axis. 2A shows the load P of the distribution line 4, FIG. 2B shows the voltage command value V * of the reactive power compensator 3, FIG. 3C shows the detected value V of the installation point voltage of the reactive power compensator 3, and FIG. ) Is the reactive current iq of the reactive power compensator 3, (e) is the secondary voltage Vt of the voltage regulator 12,
(F) shows how the tap ratio ΔT of the voltage regulator 3 changes over time. In the time scale on the horizontal axis, one scale corresponds to about 30 seconds to 2 minutes.

Here, the operation of the voltage regulator 12 will be supplemented. The operation of the voltage regulator 12 is determined by the dead band width and the operation time limit. The voltage regulator 12 detects the secondary voltage of the tap, and when the time when the secondary voltage of the tap exceeds the dead band width exceeds the operation time limit, the tap is switched so that the voltage enters the dead band width. Controlled. The operation time limit is usually set to about 30 seconds to 2 minutes.

In FIG. 5, the period from t0 to t1 is in a steady state. When the load P of the distribution line suddenly decreases at time t1, the detected value V of the installation point voltage of the reactive power compensator increases. In response, the reactive power compensator 3
Immediately outputs a reactive current (about several cycles) to suppress voltage fluctuation (d). As a result, the detected value V of the installation point voltage is maintained at the command value V *. Then, t1 to t2
In the period, the load is in a constant state while being reduced, and the reactive current is continuously output from the reactive power compensator 3. Therefore, the voltage command correction circuit 21 of FIG. 1 operates, and feedback control for correcting the voltage command works so that the detected reactive current gradually approaches zero. this period,
Since the reactive power compensator 3 outputs a delayed reactive current, the voltage command value V * is gradually increased so as to reduce it to zero. As a result, the reactive current of the reactive power compensator 3 decreases, and the detected value V of the installation point voltage becomes the command value V *.
And gradually rises. At time t2, the secondary voltage Vt of the voltage regulator 12 exceeds the dead zone and passes the operation time limit, so that the tap of the voltage regulator is switched.
Lower the secondary voltage Vt. However, the reactive power compensator 3
, The voltage drop operates at a high speed, the reactive power becomes an advanced output, and the detected value V of the installation point voltage is maintained at the command value V * at time t2. Then, during the period from t2 to t3, the control is performed so that the advanced reactive current of the reactive power compensator 3 is set to 0, and the operation is to gradually decrease the command value V *. As a result, the reactive current of the reactive power compensator 3 approaches 0,
The detection value V of the installation point voltage also gradually decreases. At time t3, the tap of the voltage regulator 12 is further switched,
The operation is to lower the secondary voltage Vt. Also at this time, since the reactive power compensator 3 compensates for the voltage drop at high speed, the detected value V of the installation point voltage is maintained at the command value V * at the time t3. Further, the reactive power compensator 3 advances again and outputs reactive power. During the period from t3 to t4, the voltage command value V * is gradually reduced again to reduce the output of the advanced reactive current of the reactive power compensator 3 to zero. As a result,
The detection value V of the installation point voltage also gradually decreases. Then, at time t4, the state is settled to a steady state. After time t4, the reactive current of the reactive power compensator 3 is 0, and the voltage regulator 1
The two taps are switched in a two-tap lowering direction as compared to before the load change. That is, the compensation for the voltage rise due to the load change is performed in the steady state in the reactive power compensator 3.
From the voltage regulator 12. In addition, the reactive power compensator 3 and the voltage regulator 12 are independently controlled, and no control signal is transmitted between them for coordination. That is, in the related art, it was necessary to transmit a control signal from the reactive power compensator 3 to the voltage regulator 12.
In the present embodiment, as shown in FIG. 1, the reactive power compensator 3 and the voltage regulator 12 are independent in control, and the reactive power compensator 3 does not transmit a signal from the When the output of the power compensator 3 is large and continues for a long time, the voltage regulator 12 can share the voltage compensation, and the output of the reactive power compensator 3 can be reduced.

In this embodiment, the detected value V of the installation point voltage of the reactive power compensator 3 shown in FIG.
In the secondary voltage Vt of the voltage regulator 12 shown in (b), at times t2 and t3, although the voltage regulator is operating, a steep voltage fluctuation caused by the tap switching of the voltage regulator 12 occurs. The reactive power compensator 3 compensates at high speed. That is, in the process of sharing the voltage compensation from the reactive power compensator 3 to the voltage regulator 12, the voltage change occurring in the distribution line can be smoothly performed. Therefore, in the present embodiment, it is possible to reduce the effect on devices that are vulnerable to sharp voltage fluctuations, such as electronic devices connected to distribution lines.

Next, the details of the voltage command correction circuit 21 shown in FIG. 1 will be described with reference to FIGS. FIG. 6 is an example of a circuit configuration for realizing the voltage command operation circuit 21. 6, the same reference numerals as those in FIG. 1 indicate the same components. As shown in FIG. 6, the voltage command correction value calculation circuit 22 includes an integration circuit 221, a gain circuit 222, and an integration start / stop command setting circuit 223.

Here, the operation of the voltage command calculation circuit 21 of FIG. 6 will be described. The integration circuit 221 integrates the deviation e between the detected value iq of the reactive current and the steady-state command value iq * of the reactive current, multiplies this by a gain K in the gain circuit 222, and outputs the correction value ΔV of the voltage command from the gain circuit 222. Output as *. The ΔV * is added to the voltage command reference value V0 * by the adder 23, and the added value is output to the limiter circuit 24. The limiter circuit 24 limits the addition value within a preset upper and lower limit value and outputs the addition value as the system voltage command value V * to the subtractor 6 in FIG.

As described above, according to the example shown in FIG. 6, since the integrating circuit 221 is used, ΔV is maintained until the deviation e becomes zero.
* Is updated. An integration time constant of the integration circuit 221;
The magnitude of the gain K of the gain circuit 222 is related to the response time of control for bringing the reactive current to a steady state, and is set based on the operation time limit value related to tap switching of the voltage regulator 12. The sign of the gain of the gain circuit 222 is determined as follows. That is, if the sign of the detected value of the reactive current indicates that the delay is positive, the sign of the gain circuit 222 is set to be negative. At this time, if the reactive power is delayed, the correction value ΔV * of the voltage command becomes positive and the voltage command value V * increases. If the reactive power advances, ΔV * becomes negative and the voltage command value V * decreases. In either case, it works so as to reduce the reactive current. The range of the upper and lower limit values limited by the limiter circuit 24 is set, for example, corresponding to the target management width of the voltage of the distribution line 4. By providing such a limiter circuit 24, it is possible to prevent the voltage command value V * from deviating from the management target width of the distribution line 4. Further, when the input value is applied to the limiter by the limiter circuit 24, a signal is sent to the integration start / stop command setting circuit 223 so that the integration is not saturated,
The integration operation of the integration circuit 221 is stopped. Thereafter, when the input value returns below the limiter, a signal is sent to the integration start / stop command setting circuit 223 to restart the integration operation.

FIG. 7 shows a second example of a circuit configuration for realizing the voltage command operation circuit 21. 7, the same reference numerals as those in FIG. 6 denote the same items. 6 in that a comparison circuit 224 is inserted on the input side of the integration circuit 221. In this comparison circuit 221, the detection value i of the reactive current
A comparison operation is performed on a deviation e between q and the steady-state command value iq * with a preset threshold value. When the deviation e is larger than the threshold value, a constant E is output. Is output. Then, in the integration circuit 221, the comparison circuit 2
24 outputs are integrated. The operation after the integration circuit 221 is the same as in FIG. Voltage command calculation circuit 21 in FIG.
Directly integrates the deviation e, the correction value ΔV * becomes large immediately after a voltage fluctuation with a large deviation e, and the reactive current of the reactive power compensator 3 is greatly reduced immediately after the voltage fluctuation. . On the other hand, the voltage command calculation circuit 21 of FIG. 7 includes a comparison circuit 224, and the comparison circuit 224
Is integrated, the correction value ΔV * changes at a constant change rate of K × E even when the deviation e is large. For this reason, there is a characteristic that the reactive current of the reactive power compensator 3 is not narrowed down immediately after the voltage fluctuation, but is gradually narrowed down at a constant rate.

As described above, according to the embodiment shown in FIG. 1, the operation of the reactive current detecting circuit 18, the reactive current steady-state command value setting circuit 19, and the voltage command correcting circuit 21
When the output of the reactive current of the reactive power compensator 3 continues for a long time, the compensation of the voltage fluctuation is performed to the voltage regulator 12 without transmitting a control signal from the reactive power compensator 3 to the voltage regulator 12. be able to. As a result, the problem of voltage regulator malfunction due to transmission error, communication error, etc. does not occur,
A highly reliable reactive power compensation system for voltage fluctuation compensation can be realized.

FIG. 8 shows a configuration diagram of a reactive power compensation system according to the second embodiment of the present invention. In the figure, components denoted by the same reference numerals as those in FIG. 1 have the same functional configuration, and thus description thereof will be omitted. This embodiment is different from the embodiment of FIG. 1 in that, instead of the reactive current detection value iq,
That is, the reactive current command value iqref output from the voltage control circuit 7 is used. In this case, the same effects can be obtained as compared with the embodiment of FIG. 1, and the reactive current detection circuit 18 is not required, so that the configuration can be simplified.

FIG. 9 shows a configuration diagram of a reactive power compensation system according to the third embodiment of the present invention. In the figure, components denoted by the same reference numerals as those in FIG. 1 have the same functional configuration, and thus description thereof will be omitted. The present embodiment differs from the embodiment of FIG. 1 in that control using reactive power is performed instead of control using reactive current. That is, the reactive power detection circuit 25 detects the reactive power Q from the output current i and the detection voltage V of the system, and calculates the deviation e from the stationary command value Q * set in the stationary command value setting circuit 26 for the reactive power. This is obtained as an input to the voltage command correction circuit 21, and the same effects as in the embodiment of FIG. 1 can be obtained. In addition to this, according to the embodiment of FIG. 9, even when the waveform of the power supply voltage is distorted, the reactive power can be accurately calculated, so that the detection accuracy is improved and the steady output of the reactive power of the reactive power compensator 3 is constant. Can be strictly adjusted to the steady-state command value Q *. As a result, unnecessary output to the reactive power compensator 3 can be suppressed, and loss of the device can be suppressed.

FIG. 10 shows a configuration diagram of a reactive power compensation system according to the fourth embodiment of the present invention. In the figure,
The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, a voltage abnormality determination circuit 27 is provided for the configuration of FIG. 1, and based on the determination result, the steady-state command set value iq of the reactive power steady-state command value setting circuit 28
* The setting can be changed. That is, the voltage abnormality determination circuit 27 uses the sum of the output ΔV * of the voltage command correction value calculation circuit 22 and the voltage command reference value V0 * as an input signal, and uses this input value as a preset abnormality determination threshold value. Compare with If the input value exceeds the range of the threshold value for a certain period of time, it is determined that an abnormality has occurred in the voltage regulator 12 or other voltage control such as the delivery voltage control of the distribution substation, and the abnormality is detected. The signal is output to the reactive power steady command value setting circuit 28. Here, the abnormality detection signal includes
There are two types of overvoltage abnormality detection and low voltage abnormality detection. Then, when the abnormality detection signal is input, the steady instruction value setting circuit 28 switches to the steady instruction value at the time of abnormality. Here, a reactive current value that is delayed when an overvoltage abnormality is detected, and a reactive current value that is advanced when an undervoltage abnormality is detected is set as a normal command value at the time of abnormality. The voltage command correction circuit 21
Reactive current detection value iq detected by reactive current detection circuit 18
So that the steady-state value of
The voltage command value V * is sequentially calculated.

As a result, in the steady state, the reactive power compensator 3 outputs a reactive current that matches the steady command value at the time of the abnormality, and this steady output corresponds to the voltage fluctuation caused by the abnormality of the voltage regulator or the like. Suppress.

As described above, according to the embodiment of FIG.
By the operation of the voltage abnormality determination circuit 27 and the reactive current steady output command setting circuit 28, even when a failure occurs in the voltage regulator 12 and a steady voltage abnormality occurs, the voltage abnormality is detected and the reactive power is detected. Since the compensating device 3 constantly outputs the reactive current to compensate for the abnormal voltage, the voltage fluctuation compensating ability of the system can be maintained even when the voltage regulator fails.

In FIG. 10, the voltage abnormality determination circuit 27
Has been input to the steady-state command value setting circuit 28 for the output invalid flow, but as in the fourth embodiment shown in FIG. 11, the dead zone circuit 2 is provided between the reactive current detection circuit 18 and the subtractor 20.
9 and the output of the voltage abnormality determination circuit 27 is
9, when the abnormality detection signal is input from the voltage abnormality determination circuit 27, the dead zone operation of the dead zone circuit 29 may be executed. According to this, as in the case of the embodiment of FIG.
Outputs a reactive current corresponding to the dead zone width, and the steady output suppresses a voltage abnormality caused by an abnormality of the voltage regulator or the like. Therefore, even when an abnormality occurs in the voltage regulator 12 and a steady voltage abnormality occurs, the abnormal voltage is detected, and the reactive power compensator 3 outputs the reactive current constantly, whereby the abnormal voltage is detected. Since the voltage is compensated, the voltage fluctuation compensation capability of the system can be maintained even when the voltage regulator fails.

The reactive power compensating device 3 of each of the above-described embodiments is constituted by a reactive power compensating device using an inverter composed of a self-turn-off device such as an IGBT, a GTO, a power transistor, or a thyristor. A reactive power compensator using an inverter can be applied.

[0042]

As described above, according to the present invention,
When the output of the reactive power compensator continues for a long time, the voltage compensation can be shared among the voltage regulators independently without transmitting a control signal from the reactive power compensator to the voltage regulator. As a result, a problem of malfunction of the voltage regulator due to a transmission error, a communication error, or the like does not occur, and there is an effect of improving reliability for voltage fluctuation compensation.

In addition, even when an abnormality occurs in the voltage regulator and a steady voltage abnormality occurs, the reactive power compensator determines the abnormality and compensates for the abnormal voltage. This has the effect of maintaining the voltage fluctuation compensation capability of the system.

As a method of controlling the reactive power compensator, the active power and the reactive power on the load side are detected from the installation point of the reactive power compensator, and the output of the reactive power compensator is controlled so as to suppress these fluctuations. There is a way to control it,
In this case, it is not possible to compensate for the voltage fluctuation due to the fluctuation of the load on the power supply side from the installation point of the reactive power compensator. On the other hand, in the reactive power compensator of the present invention, since the voltage of the distribution line is detected, there is an effect that the voltage fluctuation due to the load fluctuation in the distribution line can be suppressed regardless of the power supply side or the load side.

In addition, in the reactive power compensator of the present invention,
Since the voltage of the distribution line is detected, the reactive voltage compensator can compensate for the sharp voltage fluctuation caused by the tap switching operation of the voltage regulator. As a result, the voltage change that occurs in the process of sharing the voltage compensation from the reactive power compensator to the voltage regulator becomes smooth, so that the influence on devices that are vulnerable to sharp voltage fluctuations, such as electronic devices connected to distribution lines, is reduced. There is an effect that can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power system to which a reactive power compensation system according to an embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating the principle of voltage compensation by reactive power control.

FIG. 3 is a diagram illustrating characteristics of voltage compensation by a voltage regulator.

FIG. 4 is a diagram illustrating characteristics of voltage compensation by a reactive power compensator.

FIG. 5 is a diagram showing operation waveforms of each unit for explaining the operation of the embodiment in FIG. 1;

FIG. 6 is a diagram illustrating a specific example of the voltage command correction circuit according to the embodiment in FIG. 1;

FIG. 7 is a diagram showing another specific example of the voltage command correction circuit of the embodiment in FIG. 1;

FIG. 8 is an overall configuration diagram of a power system to which a reactive power compensation system according to a second embodiment of the present invention is applied.

FIG. 9 is an overall configuration diagram of a power system to which a reactive power compensation system according to a third embodiment of the present invention is applied.

FIG. 10 is an overall configuration diagram of a power system to which a reactive power compensation system according to a fourth embodiment of the present invention is applied.

FIG. 11 is an overall configuration diagram of a power system to which a reactive power compensation system according to a fifth embodiment of the present invention is applied.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 AC power supply 3 Reactive power compensator 4 Distribution line 6 Subtractor 7 Voltage control circuit 8 Current control circuit 9 PWM control circuit 10 Current sensor 12 Voltage regulator 16 Voltage sensor 17 Voltage detection circuit 18 Reactive current detection circuit 19, 28 Reactive current , Steady-state command value setting circuit 20 subtractor 21 voltage command correction circuit 22 voltage command correction value calculation circuit 23 adder 24 limiter circuit 25 reactive power detection circuit 26 reactive power steady command value setting circuit 27 voltage abnormality determination circuit 29 dead zone circuit 221 Integration circuit 222 Gain circuit 223 Integration start / stop command setting circuit 224 Comparison circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Minoru Kanai 4-1-1 Kanda Surugadai, Chiyoda-ku, Tokyo Within the Electric Power Business Division, Hitachi, Ltd. (72) Tomoji Nakamura 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture No. Kokubu Plant, Hitachi, Ltd. (72) Inventor Kenji Abiko 3-7-1, Ichibancho, Aoba-ku, Sendai City, Miyagi Prefecture Inside Tohoku Electric Power Co., Inc. (72) Inventor Masanori Konno, Aoba-ku, Sendai City, Miyagi Prefecture Tohoku Electric Power Co., Inc. (72) Inventor Kazuo Takasugi 3-7-1, Ichibancho, Aoba-ku, Sendai City, Miyagi Prefecture Tohoku Electric Power Co., Inc. (72) Inventor Koji Ishibashi Tagajo, Miyagi Prefecture 2-2-1 Miyauchi Tohoku Electric Manufacturing Co., Ltd. (72) Inventor Yasuyuki Hiyama 2-2-1 Miyauchi Tagajo-shi, Miyagi Tohoku Electric Manufacturing Co., Ltd. House

Claims (8)

[Claims] 1. A reactive power compensation method for controlling an output of a reactive current or a reactive power of a reactive power compensator connected to a system in order to adjust a detected value of a system voltage to a command value.
A reactive power compensation method, wherein a command value of a system voltage is corrected so that a detected value of the reactive current or a physical quantity corresponding to the detected value gradually approaches a set value. 2. A reactive power compensator connected to a grid,
Control means for controlling the reactive current or reactive power of the reactive power compensator so as to reduce the deviation between the detected value of the system voltage and the command value. And a correction means for correcting the command value of the system voltage so that the detected value or the physical quantity corresponding to the detected value gradually approaches the set value. 3. The system according to claim 2, wherein the correction unit is configured to change the command value of the system voltage based on a detected value of the reactive current or a deviation between a physical value corresponding to the detected value and the set value so as to gradually reduce the deviation. The reactive power compensation system according to claim 2, wherein the correction is performed. 4. An integrator for integrating a detected value of a reactive current or a deviation between a physical quantity corresponding to the detected value and a set value, and an output of the integrator is added to the command value of a system voltage. The reactive power compensation system according to claim 3, further comprising an adding unit that performs the operation. 5. A comparing means for outputting a constant value when a deviation between a detected value of a reactive current or a physical quantity corresponding to the detected value and a set value exceeds a preset threshold value. 4. The reactive power compensating system according to claim 3, further comprising: integrating means for integrating the output of said comparing means; and adding means for adding the output of said integrating means to the command value of the system voltage. . 6. The correction means has a limiter circuit for limiting the magnitude of the command value of the system voltage after the correction, and stops the integration operation of the integration means when the limiter circuit operates. The reactive power compensation system according to claim 4 or 5, wherein 7. An abnormality judging means for outputting an abnormal signal when the corrected command value of the system voltage exceeds a predetermined judgment reference value. 7. The reactive power compensation system according to claim 2, wherein the set value related to the physical quantity corresponding to the detected value is changed to a large value. 8. An abnormality judging means for outputting an abnormality signal when the corrected command value of the system voltage exceeds a predetermined judgment reference value, a detection value of the reactive current or a physical quantity corresponding to the detection value. A dead zone circuit that outputs the input signal when the input value exceeds a predetermined dead zone,
7. The reactive power compensation system according to claim 2, wherein the dead band circuit is operated by the abnormal signal.