JPS6145759Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a field voltage suppression device that suppresses overvoltage generated on the field winding when a semiconductor rectifier such as a thyristor is used as an excitation device for an alternator. be.

A conventional device has a configuration as shown in FIG.
That is, in the figure, 1 is the power system, 2 is the power transmission line, 3 is the turn-on switch, 4 is the generator armature, and 5 is the power system.
is a field winding that excites the generator armature 4. 9 is a thyristor rectifier that excites the field winding 5.

Between the field winding 5 and the thyristor rectifier, there is a field breaker 6, a thyristor switch 8 for suppressing overvoltage higher than the withstand voltage applied to the thyristor rectifier 9, and a thyristor switch 8 for suppressing the application of an overvoltage exceeding the withstand voltage to the thyristor rectifier 9. This is a C-R absorber 7 that suppresses.

Ignition circuits 10 and 11 for the thyristor switch 8 are provided, respectively. The thyristor switch 8 is for bypass, and further comprises reversely connected thyristors 8a, 8b and a resistor 8c,
The thyristor switch ignition circuits 10, 11 include resistors 10a, 10b, 11a, 11 connected in series.
b, and Zener diodes 10c and 11c. When overvoltage occurs in the field circuit, it is detected by the firing circuit 10 or 11 of the thyristor switch, and based on this detection, the corresponding thyristor of the thyristor switch 8 is fired, thereby performing bypass. , suppresses overvoltage. Also, if the overvoltage is steep, C
- R absorber 7 prevents the rise of overvoltage.
After making the voltage dull, it is detected by the ignition circuit 10 or 11 as described above, and a bypass is performed to suppress the overvoltage.

In addition, the C-R absorber 7 is not only used for surge absorption, but also is a high gate drive type in which the ignition pulse of the thyristor rectifier is applied only for a very short time during the ignition period due to the high reactance of the field winding. In this case, the current does not rise enough,
Since ignition failure may occur, it has also been used as a pseudo load to prevent this. However, as this device has come to be used as an excitation device for large-capacity generators, the size of this C-R absorber has increased, making it difficult to miniaturize the original device.

This idea was made to eliminate the drawbacks of the conventional one, and in the excitation system of an alternator, a separate ignition circuit was added to the thyristor switch.
In addition, by using a high-speed switching thyristor as the thyristor switch, it is an object of the present invention to provide a field voltage suppression device that does not require a C-R absorber.

This invention will be explained below based on the embodiment shown in FIG. In the figure, the same parts as before are denoted by the same reference numerals, so the explanation will be omitted. The other parts will be explained. 12 is a shunt, 14 is a second ignition circuit of the thyristor switch, and 13 is a timing detector for detecting the timing of ignition. The above-mentioned low excitation operating state detection means is a general term for the timing detector 13 and the shunt 12. Furthermore, 8a' and 8b' are high-speed switching thyristors which have sufficiently fast turn-on characteristics against the rise of overvoltage induced by this generator and are capable of suppressing overvoltage in the field circuit.

In such a configuration, before the overvoltage induced from the generator side rises to threaten the withstand voltage of the thyristors constituting the thyristor rectifier 9,
The fast switching thyristor is turned on so that this overvoltage is suppressed to a voltage determined by resistor 8c. The conventional turn-on time delay that required a C-R absorber can be solved by the above measures. On the other hand, if the current from the thyristor rectifier 9 to the field winding 5 is not sufficient, it will not be possible to maintain the on state when the ignition pulse disappears. 12
and detecting through the timing detector 13, a pulse is emitted from the second ignition circuit 14,
Since the thyristor switch 8 is turned on, the current supplied to the thyristor rectifier 9 can be increased.

As described above, according to this invention, when it is detected that the synchronous machine is in a low excitation operating state, the ignition signal that is output from the first type ignition circuit to the high-speed switching thyristor is Since the ignition signal of Failure can be prevented. Furthermore, since the thyristor switch is constructed from a high-speed switching thyristor, the thyristor switch is fired before an overvoltage occurs between the field winding terminals, eliminating the need for an impedance element such as a C-R absorber. Therefore, since a C-R absorber connected in parallel to the field winding is not required, it is necessary to increase the capacity of an impedance element such as the C-R absorber as the output voltage increases, unlike in the past. Therefore, it is possible to obtain a field voltage suppressing device that does not increase the size of the device and is inexpensive.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of a conventional device; Figure 2 is a block diagram showing an example of a conventional device;
The figure is a block diagram showing one embodiment of this invention. 1... Power system, 2... Power transmission line, 3... Closing switch, 4... Generator armature, 5... Field winding, 6... Field breaker, 7... C-R absorber , 8...Thyristor switch, 9...Thyristor rectifier, 10, 11...Ignition circuit, 12...Shunt, 13...Timing detector, 14...Second ignition circuit, 8a', 8b'... ...Fast switching thyristor.

Claims (1)

[Scope of utility model registration request] A thyristor switch provided between the field winding terminals of the synchronous machine by rectifier excitation and an ignition signal output to the thyristor switch when the voltage between the field winding terminals exceeds a predetermined value. In the field voltage suppressing device, the thyristor switch is constituted by a high-speed switching thyristor, and the low excitation circuit detects whether or not the synchronous machine is in a low excitation operating state. An operating state detecting means is provided, and when the low excitation operating state detecting means detects a low excitation operating state of the synchronous machine, ignition is outputted from a first type ignition circuit to the high speed switching thyristor. 1. A field voltage suppression device comprising a second type ignition circuit that outputs an ignition signal separate from the ignition signal.