JPH05328608A - Equipment for controlling voltage and reactive power - Google Patents

Abstract

PURPOSE:To decrease the switching number of the taps of a transformer, by eliminating unnecessary operations for switching taps even when the voltage and the reactive power of an electric power system change by the changes of its loads. CONSTITUTION:An equipment for controlling voltage and reactive power controls the voltage and the reactive power of an electric power system by switching the taps of a tap switching transformer. In this equipment, a part 11 for predicting voltages and reactive powers and a part 12 for controlling voltages and reactive powers are provided. The part 11 predicts the voltage and the reactive power of the electric power system by a sequential type least square method from the past time-series data relative to the effective power, the voltage and the reactive power of the electric power system and from the operating data of adjacent generating stations. The part 12 takes in the predictive values of the voltage and the reactive power, which are predicted by the part 11, and judges whether these predictive values stay in predetermined ranges or not. Only when judging them not to stay in the predetermined ranges, the part 12 gives to the tap switching transformer a command for switching taps, and controls the voltage and the reactive power of the electric power system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage reactive power controller for automatically controlling reactive power in a power system.

[0002]

2. Description of the Related Art As a conventional automatic voltage reactive power controller (abbreviated as AVQC hereinafter), a drive command is given to a tap changer (LTC) provided in a transformer to adjust the tap of the transformer. In some cases, the output voltage and reactive voltage on the secondary side of the transformer are controlled by a desired range.

FIG. 4 shows an example of a system configuration to which such AVQC is applied. In FIG. 4, the generator 1 is LT
It is connected to the power system via a transformer 2 having C. AVQC is a transformer for instrument (PT) 3 and current transformer (C
T) The voltage on the secondary side of the transformer and the current on the secondary side of the current transformer are input from T, and the reactive voltage Q and the voltage V are input by the transducer 5.
To the voltage reactive power controller 6 as a process signal. This voltage reactive power control device 6 is
When V and Q deviate from the preset range for a certain time or longer, a command to tap up or down to the LTC of the transformer is output so that the secondary voltage reactive power of the transformer falls within a certain range. Control calculation is performed.

FIG. 5 is a block circuit diagram showing in detail an internal configuration example of the voltage reactive power control device shown in FIG. The voltage signal (V) and the reactive power signal (Q), which are process signals, are
It is input to the dead zone setting device 7. This dead zone setting device 7
For example, the setting is as shown in FIG. 6, and if the input signals V and Q exist in the shaded area, the dead zone output is zero. If one or both of V and Q changes and goes out of the shaded area, the dead zone setting unit 7 outputs a dead zone output in proportion to the magnitude of deviation from the shaded area. The integrator 8 has an interlock, that is, a reset signal from a timer (not shown) provided to prevent continuous LTC driving when the dead band output is zero or when tap driven by LTC. The integrator 8 is locked. Last time, LTC
When a time equal to or greater than the timer set value has passed since the tap was driven, the timer counts up and the reset signal is turned on / off depending on the presence or absence of the dead zone output signal. The reset signal is released when the V and Q input signals exceed the dead zone setting range (the shaded area in FIG. 6), and the integrator has the anti-time characteristic depending on the magnitude of the dead zone signal, and outputs the positive or negative direction signal. Output. When the positive direction signal reaches or exceeds the set value of the increasing direction detection comparator 9, the comparator output is turned on and the transformer tap-up command is output. On the contrary, if the integrator output signal is negative, the set value of the down direction detection comparator 10 is compared with the integrator output signal, and when the integrator output signal becomes equal to or less than the comparator set value, the transformer tap down command is output. If the dead band output becomes zero before the output of the integrator 8 reaches the operation level of the comparator, the reset signal causes the integrator output to become zero, and the control calculation returns to the initial state.

[0005]

By the way, for the LTC of the transformer driven by such an AVQC,
The maximum number of mechanical operations that can be performed is set, and it is important to minimize unnecessary operations from the viewpoint of maintenance and economy.

FIG. 7 shows an actual LTC operation record of a transformer driven by an AVQC. Figure 7 below
The LTC actual operation oscilloscope shown in FIG. When the system voltage rises due to a load change, the AVQC issues a tap down command to the LTC. However, since the system voltage is higher than the set range, the tap down command is issued to the LTC again after a certain time. However, this time, the system voltage is too lower than the set range, so a tap-up command is issued. As shown in the measured oscilloscope, the system voltage V and the reactive power Q change according to the change of the system load. However, the second lowering command shown in FIG. 7 is an unnecessary operation as is apparent from the fact that it is necessary to immediately raise the tap to return to the original position. In particular, even within one day, large load fluctuations occur in the morning, around daytime, in the evening, and the like, so that the number of unnecessary operations performed in a year greatly affects the life of the LTC. As described above, the conventional AVQC has a problem that unnecessary operation occurs when the system voltage or the reactive power changes due to the change of the system load.

An object of the present invention is to provide a voltage reactive power control device capable of reducing the number of tap switching operations by eliminating unnecessary tap switching operation even if the system voltage or reactive power fluctuates due to fluctuations in the system load. ..

[0008]

In order to achieve the above object, the present invention provides a voltage reactive power controller for switching and controlling a transformer tap by a tap changer having a voltage of a power system and reactive power in a transformer. , Voltage reactive power predicting means for predicting the voltage and reactive power of the power system by the recursive least squares method from the past active power, voltage and reactive power time series data of the power system and the operation signal of the nearby power plant And, the voltage value and reactive power predicted value predicted by the voltage reactive power predicting means are taken in, and it is determined whether or not these predicted values are within the set range, and only when it is determined that they do not fit And a voltage reactive power control means for giving a tap switching command to the tap switching device to control the voltage reactive power of the power system.

[0009]

In the voltage reactive power control device having such a configuration, the voltage reactive power predicting means makes it possible to approximate the time series data of the past active power, voltage and reactive power of the power system and the operation signal of the nearby power plant. When the voltage and reactive power of the future power system are predicted, the voltage reactive power control means determines whether or not the predicted value falls within the set value, and only when it does not fit, the tap of the tap switching transformer is switched. .. Therefore, even if the current voltage or reactive power is out of the set value range, if the predicted value in the near future falls within the set value range, tap switching of the tap switching transformer is not performed, and thus the number of tap switching can be reduced. .. Further, when the voltage and reactive power of the power system is predicted by the voltage reactive power predicting means, the operation signal of the nearby power plant is added, so that the prediction accuracy can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of an automatic voltage reactive power control device according to the present invention. As shown in FIG. 1, the device of this embodiment has a voltage that changes from moment to moment in the power system,
Input the active power or equivalent signal time series data obtained from the current detection signal, the voltage time series data, the reactive power time series data and the operation signal of the nearby power plant, and input the predicted voltage value and reactive power. And a voltage reactive power control unit 12 that inputs a voltage measurement value and a reactive power measurement value, a voltage prediction value and a reactive power prediction value, and outputs a tap command. It consists of

Here, the operation signals of the power plants in the vicinity are effective such as the boiler fuel injection amount 13, the steam pressure 14 before (after) the turbine first stage, or the rate of change of the control valve opening degree 15 shown in FIG. is there. That is, in the power station basic system diagram shown in FIG. 2, when increasing the output of the generator 1, the boiler 16
It is necessary to increase the fuel injection amount 13 into the fuel cell, and the output of the generator 1 increases almost in proportion to the fuel injection amount after a specific time after the fuel injection. Similarly, when increasing the output of the generator 1, it is necessary to increase the steam pressure 14 before (rear) the turbine first stage, increase the regulator valve opening 15, and increase the steam flow rate. On the other hand, the steam pressure 14 before and after the first stage of the turbine and the lower limit valve opening 1
5 and the generator output are determined by the design of the turbine 17, but the response speed is very fast. Therefore, in order to predict the generator output in the near future, the steam pressure before the turbine first stage (after) 14 The rate of change of the adjustment valve opening 15 is effective. In the figure, 18 is a condenser.

The voltage reactive power predictor 11 is shown in FIG.
Voltage model identification unit 19 and reactive power model identification
Unit 20, active power predicting unit 21, voltage predicting unit 22, and
It is composed of the effective power prediction unit 23. Voltage model identification unit 1
9 shows active power from time series data of active power and voltage.
The ARMA (auto-r
egressive moving average model) model parameters
{Ai, bj} is a least-squares estimate (eg, for linear systems
Identification: Measurement and control VO128-No4, PP291 / 299)
Its parameters and time series data of active power and voltage
It outputs to the voltage prediction unit 22. However, V (k) is voltage sample data and P (k) is valid
Sample data of power, n is AR model order, m is MA
The model order.

Similarly, the reactive power model identification unit 20 is effective
Input active power from time series data of power and reactive power
The output of the reactive power is expressed as
Parameter {c_i, d_j) Is calculated by least-squares estimation, and
Parameters and time series data of active power and reactive power
Is output to the reactive power prediction unit 23. Where Q (k) is the reactive power sample data and P (k) is
Sample data of active power, n is AR model order, m is
It is the MA model order.

Further, the active power predicting unit 21 approximates the active power with a function of time t (for example, equation (3)) from the time series data of the active power and the operation signal of the nearby power plant, and the future active power is calculated. While predicting the electric power, the voltage predicting unit 2 calculates the predicted value.
2 and the reactive power prediction unit 23. 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 22 includes a voltage model identifying unit 19
The input of the parameter of the voltage model which is the output of the power source, the time series data of the active power and the voltage, and the active power prediction value which is the output of the active power prediction unit 21 is calculated.

Further, the reactive power predicting unit 23 has parameters of the reactive power model output from the reactive power model identifying unit 20, time series data of active power and reactive power, and active power prediction output from the active power predicting unit 21. Input the value and calculate the predicted value of reactive power.

On the other hand, the voltage reactive power control unit 12 inputs the measured values of the voltage and the reactive power output from the voltage reactive power predicting unit 11 and the voltage and the reactive power of the power system, and taps the same as the conventional tap. The switching command output means is provided with a function of determining whether or not the future predicted value falls within the set value and outputting the tap switching command only when the predicted value does not fall within the set value.

According to the voltage reactive power control device having such a configuration, the voltage reactive power predicting section 11 sequentially uses the past active power of the power system, the time series data of the voltage and the reactive power, and the operation signal of the neighboring power plant. Voltage and reactive power in the near future power system are predicted by the method of least squares, and whether or not the predicted value falls within the set value is determined by the determination function of the voltage reactive power control unit 12, and only when it does not fall within the set value. Since the tap change command is output to the tap changer of the transformer, if the predicted value in the near future falls within the set value even if the current voltage or reactive power is outside the set value range, tap change is performed. The transformer taps are not switched by the transformer. Therefore, when the voltage of the power system at each time point and the value of the reactive power deviate from the set values for a certain time as in the conventional case, the number of tap switching is significantly reduced as compared with the case where the tap switching command is output. In addition, when the voltage / reactive power predicting unit 11 predicts the voltage and reactive power of the power system, the steam pressure, the regulator valve opening degree, the boiler fuel input amount, etc. before (after) the first stage of the turbine of the nearby power plant are calculated. Since the active power is predicted by taking in the operation signal, the accuracy of voltage and reactive power prediction can be improved.

[0020]

As described above, according to the present invention, even if the system voltage or the reactive power fluctuates due to the fluctuation of the system load, unnecessary tap switching operation can be eliminated and the number of tap switching can be reduced. A control device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a voltage reactive power control device according to the present invention.

[Fig. 2] Basic system diagram of a nearby power plant.

3 is a block diagram showing a configuration example of a voltage reactive power prediction unit in FIG.

FIG. 4 is a configuration diagram showing a voltage reactive power control system.

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

FIG. 6 is a diagram showing a setting range of the dead zone setting device of FIG.

FIG. 7 is an oscillograph showing the actual operation of a conventional LTC.

[Explanation of symbols]

11 ... Voltage reactive power prediction unit, 12 ... Voltage reactive power control unit, 19 ... Voltage model identification unit, 20 ... Reactive power model identification unit, 21 ... Active power prediction unit, 22 ... Voltage prediction unit, 23 ... Reactive power prediction unit.

Front Page Continuation (72) Inventor Takahiro Toyosumi 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters Co., Ltd. (72) Inventor Koichi Washimi 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Headquarters Co., Ltd. In the office

Claims (1)

[Claims] 1. A voltage reactive power control device for switching and controlling a transformer tap by a tap changer having a power system voltage and reactive power in a transformer, wherein the active power, voltage and reactive power of the past of the power system are controlled. Voltage reactive power prediction means for predicting the voltage and reactive power of the power system by the recursive least squares method from the time series data and the operation signal of the nearby power plant, and the voltage value predicted by the voltage reactive power prediction means and The reactive power prediction values are taken in, and it is determined whether or not these prediction values are within the set range. Only when it is determined that the prediction values do not fall within the set range, the tap switching command is given to the tap switching device and the voltage of the power system is determined. A voltage reactive power control device comprising: a voltage reactive power control means for controlling reactive power.