JPS59132799A - Exciter for superconductive generator - Google Patents

Abstract

PURPOSE:To suppress the commutation surge voltage producing during the normal operation and to enhance the peak voltage at a system fluctuating time by providing twice an exciting power source and a thyristor. CONSTITUTION:A breaker 11 is closed, and a power source is supplied from an exciting power transformer 3 directly to a thyristor bridge 4 or to a thyristor bridge 13 through a step-down transformer 14 during the normal operation of a generator 1. The firing angle of the thyristor of the bridge 13 is maintained substantially at 180 deg. at the normal operation time, and the firing angle of the thyristor of the bridge 4 is controlled by a pulse signal 7. The phase angle of the thyristor of the bridge 13 is controlled by a pulse signal 15 at the system fluctuating time. Further, the breaker 11 is opened and the breaker 12 is closed at the generator near terminal trouble time, a negative voltage corresponding to the peak voltage is applied from another power source to the bridge 13 to abruptly attenuate the remaining magnetic flux of a field winding.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an excitation device for a synchronous machine, and in particular, to an excitation device for a superconducting synchronous machine using electromotive conducting wire in the field winding. This improves the insulation characteristics of the field circuit by keeping the voltage and AC peak value low, and also improves the coordination of control of the field circuit in response to voltage changes in the main circuit of the generator during system fluctuations. This is to rapidly attenuate the residual magnetic flux of the generator in the event of a near-end accident.

” [Technical background of the invention and its problems] A superconducting synchronous machine with a field winding configured in a superconducting state is lighter in weight, smaller in size, and has lower loss than general synchronous machines.

This has the advantage of improving system stability. For these purposes, superconducting synchronous machines are being actively developed both overseas and in Japan. In superconducting synchronous generators, a thyristor is used directly in the field of the synchronous generator as a system stabilization measure, and an excitation device is used to control the phase of the thyristor gate.

However, since the synchronous machine is a superconductor, the circuit resistance is very small compared to the reactance, and as a result, the time constant is 10 to 100 times larger than that of a conventional synchronous machine, resulting in poor coordination.

In the above device, in order to quickly reach a predetermined excitation voltage without changing the time constant of the excitation system, the higher the peak voltage of the excitation system is, the better. However, the higher the peak voltage is, the greater the contribution it makes to the transient stability of excitation, but on the contrary, it is restricted by the insulation strength of the field circuit.

The reason for this will be explained below using the conventional device shown in FIG. In the same figure, the field winding #J2 of the generator 1 is supplied with an excitation voltage in which the secondary side AC voltage of the excitation power supply transformer 8 connected to the output circuit of the generator 1 is exchanged with DC voltage by the thyristor bridge 4. Power is supplied. This excitation power is the voltage obtained by the instrument transformer 5 in order to keep the output voltage of the generator 1 constant,
It is obtained by comparing the settled voltages with an automatic voltage adjuster 6, applying a pulse signal 7 to each thyristor gate of the thyristor bridge 4, and controlling the phase. In this case, the voltage on the secondary side of the excitation power supply transformer 8 corresponds to the top voltage of the field circuit, but the phase control of each thyristor gate is such that the maximum output is output when the phase angle is 0 degrees, and the output is output when the phase angle is 90 degrees. becomes zero, so the output voltage of the generator 1 is controlled so that the phase angle of the thyristor is used as a delay angle to the field winding 2 during rated conditions, and the peak voltage is applied to the field winding 2 during system fluctuations with the phase angle set to zero degrees. has been done. However, because the time constant is large, grid stability cannot be ensured during system fluctuations unless the peak voltage and speed response are increased compared to conventional synchronous generators. In addition, the output voltage of the thyristor is such that a surge voltage Vs as shown in Fig. 2 is generated every time there is commutation, and an AC peak value W corresponding to the peak voltage is also constantly applied. The magnitude of the peak voltage t,b increases as the secondary rated voltage of the excitation power supply transformer 8 increases, and the insulation of the field circuit is always threatened.

In addition, if a short-circuit accident or the like occurs between the armature winding and terminals of the generator 1 and the generator breaker 8, this accident is detected by a protective relay or the like, and the generator breaker 8. By opening the field breaker 9 and closing the b contact of the field breaker 9, the discharge resistor 10 is turned on, the field winding 2 is demagnetized, and the fault current is no longer supplied. It is common practice to reduce the number of accidents and prevent the spread of accidents. However, superconducting generator 1
Since the time constant of the field winding 2 is large, there is a drawback that the fault current continues for a long time.

[Purpose of the invention]

As described above, the present invention is designed to prevent surges that are constantly applied to the field circuit.
Keeps tonnage pressure and AC wave height low and can adapt to high-speed fluctuations.
A further object of the present invention is to provide an excitation device for a superconducting generator that immediately demagnetizes the residual magnetic flux of the generator field winding in the event of an accident.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. The difference in the configuration of Fig. 8 from Fig. 1 is that two thyristor circuits and two excitation power sources are installed or combined. Next, the superconducting synchronous generator configured as above The operation of the excitation device will be explained. During normal operation of the generator 1, the breaker 11 is closed, the breaker 12 is opened,
A circuit supplies power directly from the excitation power transformer 8 to the thyristor bridge 18, and a circuit supplies power to the thyristor bridge 4 via the excitation power transformer 8° down-down transformer 14. During normal operation, thyristor bridge 1
The phase angle of the gate of each of the 8 thyristors is determined by the pulse signal 1.
5 is maintained at approximately 1800°C, and the phase angle of the gate of each thyristor of the thyristor bridge 4 is controlled by a pulse signal 7 for operation. This allows the commutation surge voltage and AC peak value that occur during normal operation to be kept low. Furthermore, when the system is in oscillation, the phase angle of the gate of each thyristor of the thyristor bridge 18 is controlled by the pulse signal 15 to speed up the speed response and stabilize the system.

Furthermore, in the event of a generator close-end accident, the breaker 11 is opened, the breaker 12 is closed, and a negative voltage corresponding to the peak voltage is applied to the thyristor bridge from a reliable separate power source (not shown) via the excitation power supply transformer 16. 18 to generate magnetic flux in a direction that cancels out the residual magnetic flux of the field winding of the generator, causing the residual magnetic flux to rapidly attenuate.

〔Effect of the invention〕

As detailed above, according to the present invention, an excitation power supply transformer is provided between the generator output end and the thyristor that applies a DC converted voltage to the field circuit, and during normal operation of the generator, two excitation area transformers are provided. By supplying low-voltage power through the AC, commutation surge voltage and AC peak value that occur during normal operation can be kept low. In addition, when the system is in oscillation, a high voltage source is supplied from the excitation power transformer to increase the peak voltage, thereby stabilizing the system.

Furthermore, in the event of a premature failure at the end close to the generator, high voltage power is supplied from another reliable power source via the excitation power transformer to reduce the residual magnetic flux in the field winding of the generator. It can be rapidly damped and prevent the accident from escalating.

Note that it is also possible to use another reliable power source as the initial excitation power source.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional device, Fig. 2 is a diagram showing the state of surge and AC peak value during commutation in the thyristor bridge shown in Fig. 1, and Fig. 8 is an excitation device for a generator according to the present invention. FIG. 2 is a system diagram showing an example of FIG. 1... Superconducting synchronous generator 2... Field winding 8...
Excitation power supply transformer 4... Thyristor bridge 5...
・Instrument transformer 6...Automatic voltage regulator 7...
Pulse signal 8... Generator breaker 9... Field breaker 10... Discharge resistor 11... Breaker 12... Breaker 18... Thyristor bridge 14... Excitation power source Step-down transformer 15...Pulse signal 16...Exciting power supply transformer Agent Patent attorney Noriyuki Chika (and 1 other person) 6 507- Figure 2 Special area

Claims (1)

[Claims] In an excitation device for a superconducting generator that controls the field voltage of a generator by controlling the phase angle of the gate of a thyristor circuit, two excitation power sources and two thyristor circuits are provided, and when the generator is in normal operation, , a superconducting power generation system characterized by suppressing the surge voltage and AC peak value at the time of thyristor circuit commutation applied to the field winding, and speeding up the response of excitation during system fluctuations and generator close-end faults. Machine exciter.