JPH0464111A - Control method for reactive power compensating device - Google Patents

Abstract

PURPOSE:To immediately suppress an over voltage and to prevent disturbance from being applied to a system by outputting the output of a reactive power compensating device up to a reactive power limit value simultaneously with the detection of the over voltage, and setting the output after voltage control at an initial value just before switching in the case of switching from voltage control to reactive power control. CONSTITUTION:This device is composed of a means equipped with a circuit 15 to generate a one-shot signal by the output of an over voltage detection circuit 14, a changeover switch 16 to switch a voltage control output value to a reactive power limit set value QLIMIT during the period of the one-shot signal generated by the one-shot circuit 15 after detecting the over voltage, a one-shot circuit 17 to generate a one-shot signal for switching the changeover switch 13 to voltage control during a fixed period after the detection of the over voltage, and a feedback path 18 to return a control variable selected by the changeover switch 13 to a reactive power control system 6. Thus, the over voltage can be immediately suppressed when the over voltage is detected, and disturbance can be reduced as much as possible in the case of switching from a voltage control system to a reactive power control system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Structure of the Invention] (Industrial Application Field) The present invention relates to a method of controlling a reactive power compensator aimed at stabilizing a power system.

(Prior art) Conventionally, Cyrisk control reactor (commonly known as TCR:
Thyristor Controlled Rea
There is a reactive power compensator that has two or more different control systems for a getvalus generator that applies gate pulses to the thyristor.

FIG. 3 shows an example.

In this figure, 1 is a power system, 2 is a thyristor control reactor, 3.4 is a thyristor for its control, and 5 is a gate pulse generator, which is a thyristor control reactor 2 that adjusts the voltage of the power system 1 with its delayed reactive power. The amount of current at is controlled by the firing angle of the gate pulse given from the gate pulse generator 5 to the thyristors 3 and 4.

The symbol 6 is the reactive power control system and the reactive power setting value Q
The delayed reactive power output of the thyristor control reactor 2 is controlled to be equal to ref. At this time, a first-order lag circuit is used so that the reactive power output changes smoothly in response to sudden changes in Qref. Control signal 1 which is the output of the reactive power control system 6.
to control reactive power output.

Further, 7 is a voltage transformer, and 8 is a voltage control system. This voltage control system 8 includes a reference voltage setter 9
, a voltage detection circuit 10 , a subtracter 11 , and a PI calculation circuit 12 .
Detects the system voltage via the system voltage, and subtracts the set value Vref in the reference voltage setter 9 from the detected value to obtain the error voltage ΔV.
is detected and calculated by the PI calculation circuit 12 to obtain a current value, and outputs a control signal (2) representing the delayed reactive power, which is the control amount, as a current value so that the error voltage ΔV becomes zero.

Reference numeral 13 denotes a changeover switch, one of which inputs the control signal I0 of the reactive power control system 6, and the other input of which receives the control signal Iv of the voltage control system 8. The output end of this changeover switch 13 is connected to the input end of the gate pulse generator 5.
3, the gate pulse generator 5 receives the control signal I.
Q and the control signal 1v are selectively input, and the gate pulse generator 5 generates a gate pulse having a delayed firing angle according to either control signal to control the thyristors 3 and 4. It is done like this.

Further, the changeover switch 13 is controlled by an overvoltage detection circuit 14, and normally selects the output IQ of the reactive power control system 6, and when an overvoltage is detected by the overvoltage detection circuit 14, it switches the output IQ of the voltage control system 8 to suppress the overvoltage. Configured to select output. However, in conventional control methods,
When an overvoltage occurs during operation under reactive voltage control and the system is switched to a voltage control system, the initial value of the voltage control system is unstable, so there is a risk that it will take time for the overvoltage to be suppressed.

Furthermore, when returning from voltage control to reactive power control after the overvoltage is removed, the Iv and IQ of the two control systems are different, so the reactive power output changes stepwise, which may cause disturbance in the system.

(Problems to be Solved by the Invention) As described above, in the conventional control system, when an overvoltage occurs, the overvoltage suppression operation is delayed, or when switching from the voltage control system to the reactive power control system, the system There was a problem that there was a risk of causing disturbance.

The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide a control method for a reactive power compensator that immediately suppresses overvoltage and does not cause disturbance to the grid.

[Configuration of the Invention] (Means for Solving the Problems) The present invention is configured as an apparatus for implementing a control method for achieving the above object, for example, as shown in FIG. 1. That is, a circuit 15 that generates a one-shot signal with the output of the overvoltage detection circuit 14 and a switch for switching the voltage control output value to the reactive power limit set value QLIMIT during the period of the one-shot signal generated in the one-shot circuit 15 after overvoltage detection. A one-shot circuit 17 that generates a one-shot signal for switching the switch 16 and the switch 13 to voltage control for a certain period from the time of overvoltage detection, and a feedback path 18 that returns the control amount selected by the switch 13 to the reactive power control system 6. It consists of means including:

(Function) According to the present invention, as shown in FIG. 2, at the same time as overvoltage is detected, the output of the reactive power compensator is outputted to the limit of the reactive power by the reactive limit armor section, so that the overvoltage is immediately suppressed.
Even after the IMIT period ends, voltage control can be performed during the Tv period from the time of overvoltage detection to suppress overvoltage.

Furthermore, when switching from voltage control to reactive power control, the output after voltage control immediately before switching is used as the initial value, and control is gradually made to equal the reactive power set value Qref, thereby preventing the occurrence of disturbance immediately after switching. I can do it.

(Example) An embodiment of the present invention is shown in FIG.

Descriptions of parts in FIG. 1 that are similar to those in FIG. 3 will be omitted.

In Fig. 1, the output of the overvoltage detection circuit 14 is converted into a one-shot signal of 10 to 20 m5 (TLIMIT) by the one-shot circuit 15, and the selector switch 16 is operated with this one-shot signal to output voltage control from the time of overvoltage detection to TLIMIT. is the reactive power limit setting value (Q LIM
IT), and on the other hand, the output of the overvoltage detection circuit 14 is made into a one-shot signal of TV (approximately 500 mS) by the one-shot circuit 17, and the voltage control system is operated during the Tv period from the time of overvoltage detection.

Also, during voltage control operation, the output of voltage control is set to Z-1 by feedback path 18 so that it becomes the initial value of reactive power control.
Import via block.

The operation of the embodiment of the present invention will be explained using a recurrence formula used for first-order delay calculations of the PI calculation circuit 12 of the voltage control system 8 and the reactive power control system 6. These recurrence formulas are as follows and are equivalent to those shown in the block diagram in FIG.

I,,,,s++i (I VLll-11+ K
HA V Lal l+ (KP (ΔV, ., -ΔV
L,,-++))1o=Iot6-+++(QR,
+ IQ (-11) / T Ninis Mansion (++) +
tn-1) indicates the current value of each variable and the value before the te slap.

If overvoltage is detected in Figure 1, the I VLn1
″″Q LIMIT is 0 Therefore, I v+a+−
(Q LIMIT + K + ΔV,,) +
(Kp (ΔV, ., -ΔV, .-2° and P
The initial value of the I calculation circuit 12 can be set to Q LIMIT. That is, the overvoltage can be suppressed by outputting the output of the reactive power compensator to the limit at the same time as detecting the overvoltage.

On the other hand, during operation under voltage control, Iv returns to the reactive power control system through feedback path 18 and Z-1, so I QLn) = I Vtn-11+ (Q telI
VLll-yo,)/T. Therefore, when switching from voltage control to reactive power control, reactive power control gradually (with time constant T1) IQ-I□ with the output immediately before voltage control switching as the initial value.

Return to The above explanation is shown in FIG. 2 as a time chart. This is a chart when the reactive power control system 6 detects an overvoltage during operation and switches to the voltage control system 8, and then returns to the reactive power control system 8.

As described above, according to this embodiment, when an overvoltage is detected, it can be suppressed immediately, and the disturbance when switching from the voltage control system to the reactive power control system can be minimized.

[Effects of the Invention] According to the present invention, it is possible to provide a control method for a reactive power compensator that can suppress an overvoltage immediately after detecting the overvoltage and can switch to a reactive power control system without disturbing the power system.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the main parts of an embodiment for realizing the control method of the present invention, Fig. 2 is a timing chart showing the operation of the embodiment, and Fig. 3 shows a conventional control system. FIG. 2 is a block diagram of a reactive power compensator. DESCRIPTION OF SYMBOLS 1... Power system, 2... Cyrisk control reactor, 3.4... Cyrisk for control, 5... Gate pulse generator, 6... Reactive power control system, 7... Voltage transformer , 8... Voltage control system, 9... Reference voltage setting device, 1
0...Voltage detection circuit, 11... Arithmetic unit, 12...
PI calculation circuit, 13... changeover switch, 14...
Overvoltage detection circuit, 15... one-shot circuit, 16.
...Selector switch, 17...One-shot circuit, 18
...feedback path.

Claims (1)

[Claims] A reactive power compensator including a voltage control system including a PI control circuit in a control system for controlling a firing angle given to a reactive power control thyristor, and a reactive power control system including an integrating circuit,
When overvoltage is detected during operation in the reactive power control system, the voltage control system is switched to suppress the overvoltage, and at this time, the initial value of the voltage control system is set to the output limit value of the reactive power compensator. 1. A method for controlling a reactive power compensator, which performs voltage control and, when switching to a reactive power control system again, sets the output of the voltage control system immediately before switching as the initial value of the reactive power control system.