JPH09154284A - Power converter controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep constant a system voltage by quickly detecting a variation of terminal voltage, compensating for a reactive current to keep constant an internal voltage of a self-oscillating converter and then adding this compensating value to the reference value of reactive current. SOLUTION: A terminal voltage detecting means 14 is provided to quickly detect a terminal voltage. An internal voltage constant control means 21 is also provided to compensate for a reactive power reference on the basis of the voltage variation detected by the terminal voltage detecting means 14 to keep constant the internal voltage of the self-oscillating converter. An output of the internal voltage constant controlling means 21 is added in an adder 31 provided at the output stage of a system voltage constant controlling means 23. Moreover, this added value is added 31 to an output of the reactive current detecting means 13 to input to the reactive current control means 24. An output of the terminal voltage detecting means 12 is added to 31 the output of this control means 24 to control the power converter 3 via the PWM gate control means 25. Thereby, the system voltage can be kept at the predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-turn-off device (hereinafter, simply referred to as a G-turn, such as a gate turn-off thyristor).
The present invention relates to a power converter configured by a TO) and connected to a power system via a transformer, and particularly to a controller for the power converter that maintains an internal voltage of the converter.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional technique.
The block diagram of the control apparatus of the power converter (henceforth a self-exciting converter) comprised by is shown. In FIG. 3, a self-excited converter 3 is connected to a power system 1 via a transformer 2,
A DC power source such as the capacitor 4 is connected to the DC side.

The system voltage detecting means 11 detects the system voltage via the instrument transformer 6, and the adding means 31 derives the difference between the detected system voltage and the set value of the system voltage reference setting means 22. , To the system voltage constant control means 23.

The constant system voltage control means 23 calculates the reactive current reference by the difference between the system voltage measured through the above-mentioned voltage transformer 6 and the set value of the system voltage reference setting means 22.
Further, in the reactive current control means 24, the reactive current measured by the reactive current detection means 13 via the instrument current transformer 5 and the reactive current reference created by the system voltage constant control means are added by an adder 31.
To produce a difference and thereby calculate the converter internal voltage control signal.

The converter internal voltage control signal and the terminal voltage measured by the terminal voltage detection means 12 are added by the adder 31 and input to the PWM gate control means 25, where GT
The ignition timing of O is determined and output.

The outline of the operation is as follows. When the voltage of the power system fluctuates, the reactive current of the self-excited converter 3 changes, so that the reactive current control means 24 having a fast response operates to maintain the reactive current, and the reactive current is maintained at the reactive current reference. To do. Next, the system voltage constant control means 23 having the slowest response operates to change the reactive current reference within the output range of the converter to maintain the system voltage.

In order to operate the self-excited converter 3 within the allowable current withstanding capacity of the semiconductor element, the reactive current control means 24 has a faster response so that it operates in preference to the system voltage constant control means 23. The control system is configured in.

[0008]

In the above-mentioned conventional technique, the system voltage is maintained after the system voltage constant control means 23 having a slow response operates, so that the reactive current control means 24 operates at high speed immediately after the system voltage fluctuation. As a result, the reactive current is controlled to be constant and decreases. Therefore, there is a problem that the voltage maintaining capability is inferior to that of a synchronous phase shifter or the like in which the internal voltage can be regarded as constant.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a power converter having an excellent voltage maintaining function when the system voltage fluctuates.

[0010]

A control device for a power converter according to a first aspect of the present invention detects a terminal voltage change at high speed and disables the self-excited converter so that the internal voltage becomes constant. It is provided with a means for correcting the current reference. Therefore, by calculating the reactive current correction amount and adding it to the reactive current reference value, the reactive current is controlled, so that the system voltage can be maintained.

A power converter control device according to a second aspect of the present invention detects a terminal voltage change at high speed, and corrects a system voltage reference so that the internal voltage of the self-excited converter becomes constant. It is equipped with. Therefore, by calculating the system voltage correction amount and adding this to the system voltage reference value, the reactive current is controlled, so that the system voltage can be maintained.

According to a third aspect of the present invention, in the power converter control device according to the first or second aspect, the power converter is a reactive power compensating device for controlling the reactive power. Therefore, the same can be applied to the reactive power compensator as described above.

[0013]

1 is a block diagram of an embodiment of a control device for a power converter according to claim 1 of the present invention. In FIG. 1, the same parts as those in FIG.

The feature of this embodiment is that the terminal voltage detecting means 14 for detecting the terminal voltage at high speed and the reactive current based on the detected voltage change so that the internal voltage of the self-excited converter becomes constant. The point is that the internal voltage constant control means 21 for correcting the reference is provided.

The output of the internal voltage constant control means 21 is added to the adder 31 provided at the output means of the system voltage constant control means.
It is configured to be installed in. Other configurations are the same as those in FIG.

Next, the operation will be described. First, immediately after the drop in the system voltage, the internal voltage signal is added with the terminal voltage signal detected by the terminal voltage detecting means 12.
The output from 31 drops, reducing the reactive current output. However, by passing the terminal voltage signal VT through a high-pass filter represented by a transfer function such as T1S / (1 + T1S),
The terminal voltage detecting means 14 detects the amount of change ΔVT.

Then, the reactive current reference IQr is corrected so that the internal voltage VI of the self-excited converter is constant, that is, the variation ΔVI becomes zero. The change in reactive current is given by equation (1), where XI is the internal reactance of the converter. Here, the correction amount for making the internal voltage constant, that is, the change amount ΔVI zero, is given by the equation (2).

[0018]

## EQU1 ## ΔIQ = (ΔVI−ΔVT) / XI ……………… (1) ΔIQ = −ΔVT / XI = −T1S / (1 + T1S) / XI * VT …… (2)

In order to correct the reactive current reference by this correction amount, if it is added to the reactive current reference and added to the reactive current control means 24, the internal voltage VI is recovered and the reactive current IQ increases.
The system voltage can be maintained at high speed. After that, the system voltage constant control means 23 operates to maintain the system voltage. According to this embodiment, it is possible to provide a highly reliable device having a function of keeping the internal voltage of the self-exciting converter constant.

FIG. 2 is a block diagram of an embodiment of a control device for a power converter according to claim 2 of the present invention. 2, the same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

The characteristic part of this embodiment is that the terminal voltage detecting means 14 for detecting the terminal voltage at high speed and the system based on the detected voltage change so that the internal voltage of the self-excited converter becomes constant. Internal voltage constant control means for correcting voltage reference value
It is a point equipped with 21. The system voltage constant control means 23 in FIG. 1 is deleted and a system voltage constant control means 26 is provided instead.

Next, the operation will be described. Immediately after the system voltage drops, the terminal voltage detection signal of the terminal voltage detection means 12 is added, so the internal voltage signal output from the adder 31 drops and the reactive current output decreases. The means 14 detects the change ΔVT in the terminal voltage of the converter, and the reactive current correction calculated based on the detected voltage change is applied to the transfer function K2 of the reactive current reference calculator.
Divide by (1 + T2S) / T2S to obtain the voltage correction of equation (3).

Here, when VT is decomposed into the initial value VT0 and the variation ΔVT, the equation (4) is obtained. Here, since VT0 does not change, the output becomes zero when T2S / (1 + T2S) is passed, and the equation (5) is obtained. ,
Equation (6) is obtained.

[0024]

[Formula 2] ΔVIQ = -T2S / ((1 + T2S) K2) / XI * (VT) ... (3) ΔVIQ = -T2S / ((1 + T2S) K2) / XI * (VT0 + ΔVT) (4) ΔVIQ = -T2S / ((1 + T2S) K2) / XI * (ΔVT) ………… (5) ΔIQ = −1 / XI * ΔVT ……………… (6)

By correcting the reactive current reference value with this,
The internal voltage recovers and the reactive current output increases. By doing so, control can be performed such that the internal voltage of the self-excited converter becomes constant. After that, the system voltage constant control means 26 operates to maintain the system voltage. Note that the reactive current correction amount of the first embodiment is given by the equation (7).

[0026]

## EQU3 ## ΔIQ = -T1S / (1 + T1S) / XI * (VT) =-T1S / (1 + T1S) / XI * (VT0 + ΔVT) =-T1S / (1 + T1S) / XI * ΔVT ............ (7)

Therefore, comparing the equation (7) of the first embodiment with the equation (6) of the reactive current correction of the second embodiment, T1S / (1+
It can be seen that there is no extra response corresponding to the transfer function of (T1S), and the characteristics can be improved in this example (Example 2).
According to this embodiment, it is possible to provide a highly reliable device having a function of keeping the internal voltage of the self-exciting converter constant.

In each of the above-described embodiments, the control device of the power converter has been described as a control target, but the present invention is not limited to this. In each of the embodiments, the self-excited reactive power compensator is controlled as the control target. Of course, it is also good.

[0029]

As described above, according to the present invention, when the system voltage fluctuates, the terminal voltage change is detected at high speed, and the reactive current reference or the internal voltage of the self-excited converter becomes constant. Since the grid voltage reference is corrected, the grid voltage can be maintained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control device for a power converter showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a control device for a power converter showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a control device of a power converter showing self-excitation.

[Explanation of symbols]

 1 Power system 2 Transformer 3 Power converter 4 Capacitor 5 Current transformer for instrument 6 Transformer for instrument 11 System voltage detection means 12, 14 Terminal voltage detection means 13 Reactive current detection means 21 Internal voltage constant control means 22 System voltage reference Setting means 23, 26 System voltage constant control means 24 Reactive current control means 25 PWM gate control means 31 Addition means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Uemura No. 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu factory, Toshiba Corporation

Claims (3)

[Claims] 1. A firing pulse control is performed to calculate a reactive current reference value so as to maintain a system voltage at a system voltage reference value, and to control a reactive current of a power converter based on the reactive current reference value. In the control device of the power converter to perform, the terminal voltage detection means for detecting a change amount of the terminal voltage on the power system side of the power converter, and the reactive current correction amount calculated based on the detected terminal voltage change amount. A control device for a power converter, comprising an internal voltage constant control means for correcting the reactive current reference value by using the internal voltage constant control means. 2. A reactive current reference value is calculated to maintain the system voltage at the system voltage reference value, and ignition pulse control is performed to control the reactive current of the power converter based on the reactive current reference value. In the control device of the power converter to perform, the terminal voltage detection means for detecting a change amount of the terminal voltage on the power system side of the power converter, and a system voltage correction amount calculated based on the detected terminal voltage change amount. A control device for a power converter, comprising: an internal voltage constant control means for correcting the system voltage reference value by using the internal voltage constant control means. 3. The control device for a power converter according to claim 1, wherein the power converter is a reactive power compensator that controls reactive power.