JPS60241719A - Method of controlling thyristor converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor converter control device used for DC power transmission, grid interconnection, etc., and particularly to a method for controlling a thyristor converter suitable for adopting a fast restart method.

Conventionally, in this type of thyristor converter control device, the minimum firing angle limiter of the thyristor converter when operating as a forward converter (rectifier) has been fixed to about 10 degrees. The reason why this minimum firing angle limiter is set to about 10 degrees is that the control angle of the thyristor converter during normal operation is generally 15 degrees.
In contrast, in order to ensure a commutation margin angle (5 degrees), the minimum firing angle limiter 1 was set to 10 degrees, and even if this angle was fixed, no problem occurred.

By the way, with conventional thyristor converters, when the AC voltage is lost due to a failure in the connected system, the APPS does not function, so the thyristor converter temporarily stops, checks the recovery of the AC voltage, and then restarts the APPS operation. The thyristor conversion device is restarted after waiting for stabilization time, and there is a drawback that it takes time to restart.

Therefore, a method for restarting the thyristor conversion device called a fast restart method has been proposed to solve the above-mentioned drawbacks. This fast restart method is based on the fact that the APPS has a phase memory circuit and continues to issue firing pulses to the gate circuit of the Cyrisk in the 7th phase when AC voltage is lost.
This method allows commutation of the thyristor to be restarted at the same time as the AC voltage is restored, thereby shortening the restart time of the device.

Now, if the AC voltage on the forward converter side (rectifier side) is lost,
Since the AC voltage disappears, the thyristor converter cannot commutate, causing commutation failure and the DC voltage on the output side of the forward converter to drop. When this DC voltage decreases, due to the characteristics of the control device, a large set current (more precisely, the value obtained by subtracting the current margin from the set voltage) flows into the thyristor converter from the inverter side, resulting in the so-called INVXACR, operation. becomes. Therefore, a forward voltage is applied to the thyristor converter on the forward converter side. On the other hand, as mentioned above, since the firing pulse continues to be output to the thyristor gate circuit, after the forward voltage is applied to the thyristor converter, the phase where the pulse was first output becomes conductive, resulting in becomes a bypass pair. In the thyristor converters forming this bypass pair, it is thought that approximately the rated current flows, although it depends on the current setting value at the time of failure.

However, during normal operation, current flows through the thyristor converter for only one-third of the cycle, so the cooling design is designed to accommodate this current. On the other hand, if the binoculars are used as a spare, three times the normal load will be applied to the Cyrisk converter. This means that if the minimum firing angle limiter of the thyristor converter is fixed at about 10 degrees as in the conventional design, if an arm short circuit occurs at the same time as the AC voltage is restored, an overload will occur and the thyristor converter will be damaged. This means that there is a possibility of destruction. Therefore, in order to prevent this destruction, the thyristor converter should be designed to have a heat capacity more than three times that of the conventional one, but such a design is disadvantageous in terms of cost and is not practical. Ta.

An object of the present invention is to provide a control method for a thyristor converter in which the thyristor is not destroyed even if a fast restart method is adopted without increasing the heat capacity.

In a thyristor conversion device that adopts a fast restart method, the present invention detects AC voltage loss and at the same time controls the minimum firing angle limiter of the thyristor to increase to 90 degrees or around 90 degrees to prevent arm short circuit. The above object is achieved by suppressing the short-circuit current during operation.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an example of a thyristor converter to which an embodiment of the thyristor converter control method of the present invention is applied. The U, V, and W phases of the armature winding of the alternator 1 are connected to the input side of a thyristor converter on the forward converter side, which is made up of three-phase bridge-connected thyristors 2, and the output side is an inverse converter (not shown). connected to the side thyristor converter.

In such a thyristor converter, it is assumed that an arm short circuit F occurs in the U-phase thyristor 2 as shown in the figure. At this time, the minimum firing angle limiter of thyristor 2 is 10
degree, as shown by the solid line in Figure 2 (B),
The short circuit current begins to flow to the U-W phase from a position 10 degrees delayed from the zero voltage between the U-W phases shown in A), and then
A short-circuit current flows between the -V phases. In this case, the maximum value of the short circuit current is IP□□, and the period during which the short circuit current is flowing is T Warms.

Therefore, in the thyristor converter control method of the present invention, when the armature voltage of the alternating current generator 1 is lost, this is detected and control is performed to set the minimum firing angle limiter of the thyristor 2 to 90 degrees. If such control is performed, when the AC voltage on the armature side of the alternator 1 is restored, even if an arm short circuit occurs because the fast restart method is adopted, the second
As shown by the broken line in Figure (B), the short-circuit current begins to flow after a 90-degree electrical angle delay from the point of zero U-W correlation voltage in Figure 2 (A), and the U-'W phase-to-phase voltage increases again. When it reaches zero, the current stops. Therefore, the maximum value of the short circuit current in this case becomes N and the period during which the short circuit current flows also decreases to Tw, which reduces the load on the thyristor converter and prevents destruction of the thyristor 2 when an arm short circuit occurs. I can do it.

FIG. 3 is a block diagram showing an embodiment of a thyristor converter control device that implements the thyristor converter control method of the present invention. AC power supply 3 is connected to thyristor converter 5 via circuit breaker 4 .

The DC output current I4 of this thyristor converter 5 is transferred to the current transformer 6.
The signal is input to the arm short-circuit detection relay 7 via. The detection current of a current transformer 8 installed in the electric line between the circuit breaker 4 and the thyristor converter 5 is input to this arm short circuit detection relay 7, and the detection output of this arm short circuit detection relay 7 is sent to a protection interlocking circuit 9. It is man-powered. Further, the detected current of the current transformer 6 is manually inputted to a current-voltage converter 11 via a current transformer 10. The output of this current-voltage converter 11 is input to a subtracter 12, and this subtracter 12 receives a current set value Id.

are also input, and the difference between them is input to the ACR 13. The output of this ACR 13 is input to the minimum firing angle limiter 14, and the output of this minimum firing angle limiter 14 is APP.
It is input in S15. The output of this APPS 15 is inputted to a pulse logic 16, and the output of this pulse logic 16 is amplified by a pulse amplifier 17 and inputted via a pulse transformer 18 to the illustrated dangerous gate control circuit G of the thyristor converter 5. A limiter change command from the protection interlock circuit 9 is input to the minimum firing angle limiter 14, and a gate block command (GB) from the protection interlock circuit 9 is input to the pulse logic 16. Further, this protection interlock circuit 9 issues a circuit breaker open command CB to the circuit breaker 4, and also outputs a protection interlock request command A to the other end (not shown). Furthermore, the AC voltage that is input to the thyristor converter 5 via the voltage transformer 19 is input to the APPS 15 . Furthermore, the detection output of the undervoltage relay 20 is manually input to the protection interlocking circuit 9.

Next, the main part of the operation of this device will be explained.

When the protective interlocking circuit 9 detects the loss of AC voltage on the input side of the thyristor converter 5 through the under-appropriate pressure relay 20, the protective interlocking circuit 9 issues a command to the minimum firing angle limiter 14 to set the minimum firing angle limiter ( Ec, +-) is an electrical angle of 90 degrees. Therefore, as mentioned above, even if an arm short circuit occurs when the AC voltage is restored, the maximum value of the arm short circuit current is suppressed, and the time during which the short circuit current flows is shortened.
An excessive load is not applied to the thyristor converter 5, and destruction of the thyristor converter 5 can be prevented. In addition, in this device, when the arm short circuit relay 7 operates, the protection interlocking circuit 9
Gate block command GB=i is output to the pulse logic 16 to block the gate of the thyristor of the thyristor conversion device 5, and at the same time, an open command CB of the circuit breaker 4 is issued to cut off the short circuit current and perform a device protection operation.

According to this embodiment, when the input AC voltage of the thyristor converter 5 is lost, the protection interlocking circuit 9 increases the minimum firing angle limiter of the thyristors constituting the thyristor converter 5 to approximately 90 degrees in electrical angle. Therefore, even if an arm short circuit occurs when the AC voltage is restored, by reducing the load on the thyristor converter 5, it is possible to prevent destruction of the thyristor converter 5 without increasing the heat capacity of the thyristor converter 5. There is. Therefore, there is an effect of improving the reliability of the device at low cost while keeping the installed capacity of the entire device small.

As described above, according to the thyristor converter control method of the present invention, a fast restart method is adopted by raising the minimum firing angle limiter of the thyristor converter to around 90 degrees in electrical angle at the same time as the AC voltage is lost. The thyristor converter can be prevented from being destroyed without increasing the heat capacity of the thyristor converter.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a thyristor converter to which the thyristor converter control method of the present invention is applied, and FIG.
A) is a voltage waveform diagram showing the AC voltage applied to the input side of the thyristor converter shown in Fig. 1, and Fig. 2 (B) is a voltage waveform diagram showing the AC voltage applied to the input side of the thyristor converter shown in Fig. 1. The waveform diagram and FIG. 3 are block diagrams showing one embodiment of a thyristor conversion control device to which the thyristor converter control method of the present invention is applied. 3... AC power supply, 5... Thyristor converter, 7...
・Arm short circuit detection relay, 9...Protection interlocking circuit, 14
...Minimum firing angle limiter, 15...APPS, 16
...Pulse grass 1 Engraving of the cause drawing (Change in content 1 Procedural amendment (method) 1 Indication of the case 1982 Patent application No. 92881 2 Name of the invention Control method for Cyrisk converter 3, person making the amendment 4 Sub-Agent 7, Figure 2 of the drawing subject to the amendment. & Contents of the amendment Figure 2 of the drawing is revised to the drawing attached to the written amendment.

Claims (1)

[Claims] 1. In a control method for a thyristor converter that uses an APPS equipped with a phase memory circuit to adopt a fast restart method that continues to issue firing pulses to the gate circuit of a thyristor in the phase before the loss of AC voltage even when AC voltage is lost. Upon detection of a loss of voltage, the minimum firing angle IJ of said thyristor converter
A method for controlling a thyristor converter, characterized in that the transmitter is increased to 90 degrees or around 90 degrees.