JPH0643947A - Voltage reactive power controller - Google Patents

Abstract

PURPOSE:To prevent malfunction due to a prediction error and also prolong the life of LTC while maintaining the reliability of control operation by predicting a near future voltage and reactive power from the past time-series data of an electric power system and determining a tap command by fuzzy inference. CONSTITUTION:This voltage reactive power controller consists of a voltage reactive power prediction part 15, a voltage integration part 16, a reactive power integration part 17, and a voltage reactive power control part 18. The voltage reactive power prediction part 15 when supplied with the active power of the power system or time series data of a signal corresponding to it, time series data of a system voltage, and time series data of reactive power calculates a voltage predicted value and a reactive power predicted value as near future predicted values of the voltage and reactive power of the power system. The voltage integration part 16 integrates the deviation of the voltage set value of the supplied system voltage from a blind sector to obtain a voltage deviation integral value DELTAV. The reactive power integration part 17 integrates the deviation of the supplied system reactive power from the reactive power set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic voltage reactive power controller.

[0002]

2. Description of the Related Art A voltage reactive power control device gives a drive command to a tap changer (hereinafter referred to as LTC) provided in a transformer and adjusts a tap of the transformer to adjust the tap of the transformer. The output voltage and reactive power are controlled within a desired range. FIG. 6 shows a prior configuration example of a power system using such a reactive power control device.

In FIG. 1, a generator 1 is connected to a power unit via a transformer 2. The transformer 2 has an LTC (not shown). The voltage and power of the power system, which is the secondary side of the transformer 2, are extracted by PT3 and CT4, respectively, and are supplied to the transducer 5. The transducer 5 obtains the reactive voltage Q representing the reactive voltage of the power system based on the voltage and current of the power system, and outputs the reactive voltage Q together with the system voltage V representing the voltage of the power system. The reactive voltage Q and the system voltage V are supplied to the voltage reactive power control unit 6 as a process signal. When the system voltage V and the reactive power Q deviate from the preset range for a certain time or longer, the voltage reactive power control unit 6 outputs a command of tap up or tap down to the LTC of the transformer 2 to output the command of the transformer 2. Secondary voltage V,
The control calculation is performed so that the reactive power Q always exists within a predetermined range.

The voltage reactive power controller 6 will be described with reference to FIG. The system voltage signal V, which is a process signal, is given to the subtractor 51, and a difference signal Δv representing a deviation from the voltage setting value Vr is obtained. This difference signal Δv is set by the dead zone setting unit 7
Is supplied to. Further, the reactive power signal Q is given to the subtractor 52, and the difference signal Δq representing the deviation from the voltage setting value Vr is obtained. This difference signal Δq is supplied to the dead zone setting unit 8. The dead zone of the dead zone setting unit 7 is set between (Vr + V ₀ ) and (Vr −V ₀ ), and when the value of the input signal is within the dead zone, the dead zone output becomes zero, and When the value of the signal is outside the dead zone, a dead zone output having a magnitude proportional to the degree of deviation from the dead zone is generated.
Similarly, the dead zone of the dead band setting unit 8 also, (Qr + Q ₀₎ and (Qr -Q ₀₎ is set between the value of the input signal is present in the dead zone, as the dead zone the output becomes zero,
Further, if the value of the input signal is outside the dead zone, a dead zone output having a magnitude proportional to the degree of deviation from the dead zone is generated. The outputs of the dead zone setting units 7 and 8 are given to integrators 9 and 10 whose operations are controlled by a reset signal supplied from a timer (not shown), respectively.

The timer is provided for preventing continuous LTC driving when the output of the dead zone setting unit is zero or when tap driven by LTC, and outputs a reset signal to output an integrator. The 9 and 10 integration operations are blocked. When a predetermined time or more set in the timer has elapsed since the tap of the LTC was driven last time, the timer counts up and the reset signal is turned off in accordance with the presence of the dead zone output, or in accordance with the absence of the output. Turn on the reset signal. Therefore, after a lapse of a predetermined time from the previous tap switching, when the difference signal Δv of the system voltage and the difference signal Δq of the reactive power exceed the dead band, the reset signal is released and the integrator starts the operation. The integrator has an anti-time characteristic depending on the size of the signal in the dead band, that is, the integration time is shortened for a large level output signal and lengthened for a small level output signal. Then, the signal is integrated and the signal in the positive or negative direction is output. Integrator 9 that accumulates the difference signal Δv that exceeds the dead zone
The integrated value ΔV of the reactive voltage deviation is supplied to the detection comparator 11. The reactive power deviation integral value ΔQ of the integrator 10 which has accumulated the difference signal Δq exceeding the dead zone is detected by the detection comparator 12
Is supplied to. If the dead band output to the integrator becomes zero before the output level of the integrator reaches the operating level of the detection comparator, the reset signal causes the integrator output to become zero, and the control calculation returns to the initial state. Be hummed

The detection comparator 11 compares the reactive voltage deviation integral value ΔV with two set values, and when the integral value ΔV exceeds the first value, generates a tap-up signal "1" for instructing tap-up of the transformer. . When the integrated value ΔV is between the first value and the second value, the signal "0" which does not change the tap is generated. When the integrated value ΔV is less than or equal to the second value, the tap down signal “−1” that commands the tap down of the transformer is generated. Similarly, the detection comparator 12 compares the reactive power deviation integral value ΔQ of the integrator 12 with two set values, and generates signals “1”, “0” and “−1” according to the levels thereof. When the output signal of the detection comparator 12 is "1", the voltage condition circuit 13 is used. When the output signal is "-1", the voltage condition circuit 14 is used, the transformer tap-up signal "1", the tap unchanged signal "0", or The tap down signal "-1" is output.

In the voltage condition circuit 13, if the system voltage V, the voltage set value Vr, and the voltage dead band width V ₀ , for example, V> Vr
When, the signal “−1” is output. Vr-V ₀
When <V <Vr, the signal "0" is output. V <V
When r −V ₀ , the signal “1” is output.

[0008] Voltage condition circuit 14, when V> Vr + V _0, outputs a signal "-1". Vr <V <Vr + V ₀
When, the signal “0” is output. When V <Vr, the signal "1" is output. Switching of the LTC of the transformer 2 is controlled based on these signals.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The maximum number of mechanical operations is defined from the viewpoint of preventive maintenance, and it is important from an economical point of view to suppress unnecessary operations.

An actual LTC operation record driven by a voltage reactive power controller set on a transformer is shown in FIG.

In FIG. 8, since the system voltage has risen due to a change in the load, the voltage reactive power control device issues a tap down command to the LTC (a in the same figure). After a certain time when the system voltage was higher than the set range, the tap down command was again issued to the LTC (FIG. 11B). However, the system voltage has dropped too much below the set range, so a command to raise the tap is issued (c in the same figure). The system voltage V and the reactive power Q change according to the fluctuation of the load of the power system as shown in the measured oscilloscope.

However, the second tap down command shown in FIG. 8 is an unnecessary LTC operation because it is necessary to immediately raise the tap to return it to the original position. It was Large load changes occur multiple times in the morning, around noon, in the evening, etc.
The number of unnecessary operations of C has a great influence on the life of the expensive LTC.

As a means for solving this problem, Japanese Patent Application No. 4-43746 proposes a voltage reactive power control device having a prediction function. The method of the present invention predicts the near future voltage and reactive power of the power system, and predicts the future predicted value even if the present voltage or reactive power is out of the specified range and the output of the integrator satisfies the tap operation condition. If the value is within the value, it is solved by not performing tap switching. However, since it is crisply determined whether or not the predicted value is within the specified value, there is a possibility that an erroneous judgment may be made for the prediction error.

Therefore, an object of the present invention is to provide a voltage reactive power control device capable of suppressing an unnecessary operation of LTC while avoiding a malfunction due to a prediction error.

[0015]

In order to achieve the above object, in the voltage reactive power control device of the present invention, the voltage reactive power for automatically controlling the voltage of the power system and the reactive power by switching the tap of the transformer. In the control device, voltage reactive power predicting means for predicting the near future voltage and reactive power of the power system from the past time series data in the power system to obtain a voltage predicted value and a reactive power predicted value, and the power system A voltage integrator that inputs a voltage and integrates the deviation from the dead band for the voltage setting value to obtain a voltage deviation integrated value, and inputs the reactive power of the above power system to integrate the deviation from the dead band for the reactive power setting value and invalidate it. Reactive power integrating means for obtaining a power deviation integrated value, and fuzzy based on the voltage predicted value, the reactive power predicted value, the voltage deviation integrated value, and the reactive power deviation integrated value Run the inference, characterized in that it comprises a voltage reactive power control means for outputting a tap operation command for instructing the tap changer of the transformer.

[0016]

The voltage reactive power controller of the present invention is based on the near future predicted values of the voltage and reactive power of the power system and the integrated value of the deviation of each of the voltage and reactive power of the power system from the reference value. Furthermore, since fuzzy inference is executed to determine tap switching, it is possible to avoid misjudgment with respect to future prediction errors of system voltage and reactive power as much as possible.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a voltage reactive power control device of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a voltage reactive power control device of the present invention. The voltage reactive power control device includes a voltage reactive power predicting unit 15, a voltage integrating unit 16, a reactive power integrating unit 17, and a voltage reactive power. Control unit 1
It is composed of 8.

When the reactive power predictor 15 is supplied with active power of the power system or time-series data of signals corresponding thereto, time-series data of system voltage and time-series data of reactive power, the voltage of the power system and A voltage predicted value and a reactive power predicted value that are predicted values of the reactive power in the near future are calculated. The voltage integrator 16 integrates the deviation of the supplied system voltage from the dead zone with respect to the voltage setting value to obtain a voltage deviation integral value ΔV. The reactive power integration unit 17 integrates the deviation of the supplied system reactive power from the dead zone with respect to the reactive power setting value to obtain a reactive power deviation integrated value.

The voltage predicted value, the reactive power predicted value, the voltage deviation integrated value, and the reactive power deviation integrated value are supplied to the voltage reactive power controller 18. The voltage reactive power control function 18 executes fuzzy inference based on these inputs and generates a tap operation command for instructing tap switching.

The voltage reactive power prediction unit 15 outputs a near future voltage prediction value and reactive power prediction value based on various time series data of the past power system (active power, voltage, reactive power in FIG. 1). . As a method of predicting system voltage and reactive power, ARMA (Auto-Regressive Moving-Average Model)
An appropriate method such as a method using a prediction model such as a model or a method using a hierarchical neural network can be used.

FIG. 2 shows an example of the configuration of the voltage reactive power predicting unit 15 when the ARMA model is used. The voltage reactive power prediction unit 15 receives the time series data of the active power of the power system or a signal corresponding thereto, the time series data of the voltage of the power system and the time series data of the reactive power from a transducer (not shown), and receives the time series data of the system. The predicted value of voltage and the predicted value of reactive power are output. As shown in FIG. 2, the voltage model identification unit 15a and the reactive power model identification unit 15 are provided.
b, the active power prediction unit 15c, the voltage prediction unit 15d, and the reactive power prediction unit 15e. The voltage model identifying unit 15a receives the active power from the time series data of the active power and the system voltage, and outputs the voltage as the ARMA of the equation (1).
Least-squares estimation of model parameters {a _i , b _j } (eg linear system identification: measurement and control Vol 28-No
4, PP 291/299), and supplies the parameter and the time series data of the active power P and the grid voltage V to the voltage prediction unit 15d.

[0022] Here, V (k) is the k-th sample data of the system voltage, V (k-i) is the k-i-th sample data of the system voltage, and P (k-j) is the k-j-th sample of the active power. Data, n is the AR model order, and m is the MA model order.

Similarly, the reactive power model identification unit 15b is
The parameters {c _i , d _j } of the ARMA model of equation (2) that inputs active power and outputs reactive power from time series data of active power and reactive power are calculated by least-squares estimation,
The parameters and the time series data of the active power P and the reactive power Q are supplied to the reactive power predicting unit 15e.

[0024] Here, Q (k) is the k-th sample data of the reactive power, Q (k-i) is the k-i-th sample data of the reactive power, and P (k-j) is the k-j-th sample of the active power. Data, n is the AR model order, and m is the MA model order.

The active power predicting unit 15c approximates the active power from the time series data of the active power by a function of time t, for example, equation (3), and the active power at future sample points t ′, t ″, ... Is predicted and the predicted values P ′, P ″ ... Are supplied to the voltage prediction unit 15d and the reactive power prediction unit 15e.

P (t) = P ₀ + P ₁ * t + P ₂ * t ² (3) However, P ₀ , P ₁ and P ₂ are parameters and are determined by, for example, the least square method.

The voltage predicting unit 15d includes a voltage model identifying unit 1
5a based on the parameters of the voltage model, the time series data group of active power, the time series data group of system voltage, and the active power prediction value output from the active power prediction unit 15,
The predicted value of the system voltage is calculated by the above equation (1). That is, using the time series data group of the past system voltage and the time series data group of the active power, the sample output V at the future first sampling point t ′ of the next system voltage is calculated by the equation (1).
Find (k). This is a predicted value and will be the first sampled value V ′ of the future system voltage. This is added to the time series data of system voltage. The active power P ′ at the first sampling point t ′ is fetched from the active power predictor 15c and added to the active power time series data group. The second sampled value V of the system voltage at the future sampling point t ″ is calculated by the formula (1) using the time-series data of the system voltage and active power.
'' Also, the predicted value P ″ of the active power at the second sampling point t ″ is taken in from the active power prediction unit 15. Sample values V ″ and P ″ are further added to the time series data (including V ′ and P ′) of the system voltage and active power, and the future third sample point t ″ is calculated according to the equation (1). The third sampled value V '''of the system voltage at the''is obtained. Such calculation is repeated up to the position of the desired sample point t ^{n ′} on the time axis to be predicted, and the system voltage V ^{n ′} at the future sample point t ^{n ′, which} is several samples to several tens of samples ahead, is predicted.
The predicted value of the obtained system voltage after a predetermined time is supplied to the voltage reactive power control unit 18.

The reactive power predicting unit 15e outputs the parameters of the reactive power model output from the reactive power model identifying unit 15b, the time series data group of active power, the time series data group of reactive power, and the output of the active power predicting unit 15c. Based on a certain active power prediction value, the reactive power prediction value is calculated by the above equation (2). That is, the sample output Q (k) at the next first sampling point t ′ of the next reactive power is calculated by the equation (2) using the time series data group of the past system voltage and the time series data group of the active power. . This is a predicted value and will be the first sampled value Q ′ of the future system voltage. This is added to the time series data of reactive power. The active power P at the first sampling point t'from the active power predictor 15c
′ Is taken in and added to the time series data group of active power. The second sample value Q ″ of the reactive power at the future sample point t ″ is obtained by the equation (1) using the time series data of the reactive power and the active power. Further, the predicted value P ″ of the active power at the second sample point t ″ is taken in from the active power prediction unit 15c. In addition to the time series data of reactive power and active power (including Q'and P '), sample value Q'',
P ″ is added, and the third sample value Q ′ ″ of the reactive power at the future third sample point t ′ ″ is calculated by the equation (1). Such calculation is repeated up to the position of the desired sample point t ^{n ′} on the time axis to be predicted, and, for example, the reactive power Q ^{n ′} at the future sample point t ^{n ′} from several samples to several tens of samples ahead is predicted. The predicted value of the obtained reactive power after a predetermined time is supplied to the voltage reactive power control unit 18.

The voltage integrator 16 is composed of the subtractor 51, the dead zone setting unit 7 and the integrator 9 shown in FIG.
A voltage deviation integral value ΔV is obtained from the system voltage V, the voltage set value Vr, and the dead zone width V _0, and the voltage deviation integral value ΔV is obtained.
Supply to 8. The reactive power integrator 17 is configured by the subtractor 52, the dead zone setting unit 8 and the integrator 10 shown in FIG. 7, and calculates the reactive power deviation integral value ΔQ from the reactive power Q and the reactive power set value Qr and the dead zone width Q _0. Then, this is supplied to the voltage reactive power control unit 18. Since the voltage integrator 16 and the reactive power integrator 17 operate in the same manner as the conventional circuit shown in FIG. 7, their description will be omitted.

The voltage reactive power control unit 18 performs fuzzy inference based on the supplied voltage deviation integrated value, reactive power deviation integrated value, predicted voltage value and predicted reactive power value, for example, according to the following rules, and performs tap switching. Determine control. Voltage rule 1) IF ΔV is P and V _p is Low THEN TAP is UP 2) IF ΔV is P and V _p is Just THEN TAP is HOLD 3) IF ΔV is P and V _p is High THEN TAP is HOLD 4) IF ΔV is Z THEN TAP is HOLD 5) IF ΔV is N and V _p is Low THEN TAP is HOLD 6) IF ΔV is N and V _p is Just THEN TAP is HOLD 7) IF ΔV is N and V _p is High THEN TAP is DOWN Reactive power rule 1) IF ΔQ is P and Q _p is Low and V <V _r and V _p <V _r
THEN TAP is UP 2) IF ΔQ is P and Q _p is Low and V <V _r and V _p > V _r
THEN TAP is HOLD 3) IF ΔQ is P and Q _p is Just and V <V _r THEN TAP i
s HOLD 4) IF ΔQ is P and Q _p is High and V <V _r THEN TAP i
s HOLD 5) IF ΔQ is P and V _r <V <V _r + V ₀ THEN TAP is HOLD 6) IF ΔQ is P and Q _p is Low and V> V _r + V ₀ and V _p
> V _r + V ₀ THEN TAP isDOWN 7) IF ΔQ is P and Q _p is Low and V> V _r + V ₀ and V _p
<V _r + V ₀ THEN TAP is HOLD 8) IF ΔQ is P and Q _p is Just and V> V _r + V ₀ THEN T
AP is HOLD 9) IF ΔQ is P and Q _p is High and V> V _r + V ₀ THEN T
AP is HOLD 10) IF ΔQ is Z THEN TAP is HOLD 11) IF ΔQ is N and Q _p is Low and V> V _r THEN TAP is
HOLD 12) IF ΔQ is N and Q _p is Just and V> V _r THEN TAP
is HOLD 13) IF ΔQ is N and Q _p is High and V> V _r and V _p >
V _r THEN TAP is DOWN 14) IF ΔQ is N and Q _p is High and V> V _r and V _p <
V _r THEN TAP is HOLD 15) IF ΔQ is N and V _r -V ₀ <V <V _r THEN TAP is HOLD 16) IF ΔQ is N and Q _p is Low and V <V _r -V ₀ THEN TA
P is HOLD 17) IF ΔQ is N and Q _p is Just and V <V _r -V ₀ THEN
TAP is HOLD 18) IF ΔQ is N and Q _p is High and V <V _r -V ₀ and
V _p <V _r -V ₀ THEN TAPis UP 19) IF ΔQ is N and Q _p is High and V <V _r -V ₀ and
V _p > V _r -V ₀ THEN TAPis HOLD where ΔV is the voltage deviation integrated value, ΔQ is the reactive power deviation integrated value, V _p is the voltage predicted value, Q _p is the reactive power predicted value, and V _r
Is a voltage setting value, V ₀ is a voltage dead band width, and TAP is a tap value.

An example of the membership function used in the above inference is shown in FIGS. 3a and 4a are so-called adjustment parameters. Vb and -Vb in FIG. 3B are adjustment parameters. Q _b, -Q shown in FIG. 4 (b)
_b is an adjustment parameter. Figure 4 _(c), V c in the (d) and FIG. 5 (a) is an adjustment parameter.

Next, as the fuzzy inference method, any of several proposed methods may be used. For example, the inference value TAP is calculated using the following formula.

Inference of control rule by voltage However, WV _i is the fitness of the i-th rule, and T _i is the consequent part membership function value of the i-th rule.

Rule inference with reactive power However, the conformity T _i of the i-th rule is WQ _i is the i-th rule.
It is the consequent part membership function value of the second rule.

A tap command is output based on the obtained TAP value under the condition of the following equation.

TAP _v <-vlim OR TAP _Q <-qlim tap down command TAP _v > vlim OR TAP _Q > qlim tap up command where vlim is the threshold value of the voltage rule inference value, qlim
Is the threshold value of the reactive power rule inference value.

In this way, the tap switching of the transformer is controlled based on the prediction result of the system voltage and reactive power in the near future, and the target of each voltage and reactive power is controlled so that the deviation from the control target state does not increase. Further control is performed using the integrated value of the deviation from the value, and both controls are adjusted by fuzzy reasoning. For this reason, the number of times of switching in the tap switching control of the transformer is reduced as much as possible, and it is possible to avoid a situation in which the power supply system goes down due to improper control due to an incorrect future value due to a prediction error. It will be possible.

In order to obtain the voltage and reactive power of the future electric power system, the past data is input by using a so-called neural network in which the past data is input to the above-described prediction model and the future value is output. Since various methods such as a method of empirically outputting a future value can be appropriately used, the method is not limited to the method of the embodiment.

[0039]

As described above, the voltage and reactive power control apparatus of the present invention predicts the near future voltage and reactive power from the past time series data of the power system, so that the voltage and reactive power can be restored in a relatively short time. It is possible to avoid a tap operation that requires tap switching, and it is also possible to prevent a malfunction due to a prediction error by determining a tap command by fuzzy inference. This makes it possible to extend the life of the expensive LTC while maintaining the reliability of the control operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a voltage reactive power control device of the present invention.

FIG. 2 is a block diagram showing a configuration example of a voltage reactive power prediction unit 15.

FIG. 3 is a graph showing an example of a membership function.

FIG. 4 is a graph showing an example of a membership function.

FIG. 5 is a graph showing an example of a membership function.

FIG. 6 is a block diagram showing a configuration example of a conventional voltage reactive power control system.

FIG. 7 is a block diagram showing a configuration example of conventional voltage reactive power control.

FIG. 8 is an oscillograph showing an actual operation example of LTC.

[Explanation of symbols]

 15 Voltage Reactive Power Prediction Section 16 Voltage Integrating Section 17 Reactive Power Integrating Section 18 Voltage Reactive Power Control Section

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinji Hayashi 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Within Toshiba Research Institute, Inc. (72) Inventor Takahiro Toyosumi 1-chome, Shibaura, Minato-ku, Tokyo No. 1 in Toshiba Head Office

Claims (1)

[Claims] 1. A voltage reactive power control device for controlling voltage and reactive power of a power system by switching taps of a transformer, wherein voltage and reactive power of the power system in the near future are determined from past time series data of the power system. Voltage reactive power predicting means for predicting electric power to obtain a voltage predicted value and a reactive power predicted value, and voltage integration for inputting the voltage of the power system and integrating a deviation from a dead zone with respect to a voltage set value to obtain a voltage deviation integrated value Means, reactive power integrating means for inputting reactive power of the power system to obtain a reactive power deviation integrated value by integrating a deviation from a dead zone with respect to a reactive power set value, the voltage prediction value, the reactive power prediction value, the Fuzzy inference is performed based on the integrated value of voltage deviation and the integrated value of reactive power, and a tap operation command that commands tap switching of the transformer is output. A voltage reactive power control device comprising: a power control means.