JPH057957B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a field circuit protection device for a superconducting rotating electric machine, and particularly to a protection device against abnormal high voltage generated in a field circuit of a rotating electric machine.

[Background of the invention]

In general, as the excitation method for rotating electric machines such as turbine generators, the so-called thyristor direct excitation method is often adopted, which takes excitation power from the output side of the generator, rectifies it with a thyristor, and supplies it to the field winding of the generator. There is. In this method, a thyristor overcurrent protection method has been conventionally used as a countermeasure against overcurrent caused by a short circuit accident on the DC side of the thyristor. An example is shown in FIG.

In Fig. 1, 1 is a synchronous generator, 2 is a field winding thereof, 3 is an excitation transformer, 4 is a thyristor excitation device, 5 is a thyristor gate control device, 6 is a field magnet and disconnector, and 7 is a thyristor gate control device. A discharge resistor, 8 a current detector such as an ammeter shunt, 9 an amplifier, and 10 an overcurrent protection circuit. This device detects the current with a current detector 8 when an overcurrent flows through the field winding 2, and amplifies the detection signal with an amplifier 9 and supplies it to the overcurrent protection circuit 10. The output controls the thyristor gate control device 5, which narrows down the gate of the thyristor excitation device 4 to rapidly suppress the current flowing through the field winding 2, and when the current is reduced to zero, the field is turned off or disconnected. The device 6 is opened and a discharge resistor 7 is inserted to prevent an overcurrent accident in the field circuit.

However, such a protection device cannot be applied to a superconducting synchronous generator 1. In other words, in a superconducting generator, when the superconducting state of the superconducting field winding is destroyed (quenched), resistance is generated in the part where the resistance was zero until then, and an abnormal high voltage is generated in the superconducting field winding. There is a high risk that voltage will be generated and the superconducting field windings will be damaged.

Generally, the field is controlled to be shut off when a quench accident occurs, but in that case, the output side system of the generator must be shut off before the field shutoff is performed. Therefore, there is a certain time delay before the field is cut off, and there is a risk of fatal damage to the superconducting field windings during this time.

[Purpose of the invention]

It is an object of the present invention to provide field circuit protection for a superconducting rotating electrical machine that eliminates the above-mentioned drawbacks of the prior art and can protect the superconducting field winding from abnormal high voltages associated with quench accidents that occur in the superconducting field winding. We are here to provide you with the equipment.

[Summary of the invention]

In order to achieve the above object, the present invention provides a system for exciting a superconducting field winding of a superconducting rotating electrical machine using a thyristor excitation device connected to a grid via a transformer, in which a field including a superconducting field winding is provided. By providing means for detecting abnormal high voltage generated in the circuit and means for controlling the thyristor excitation device to operate as an inverter based on the detection signal, it is possible to quench the superconducting field winding generated on the DC side of the thyristor excitation device. The system is characterized in that the energy caused by the accident is regenerated into the grid to rapidly reduce the abnormally high voltage in the superconducting field windings.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the invention. In this figure, the same parts as in Fig. 1 are given the same symbols, so to explain the different parts, 1 is a synchronous generator, but its field winding 2 is configured as a superconducting field winding. This is a superconducting power generator. 11 is a protection resistor made of a high resistance for voltage detection connected in parallel with the superconducting field winding 2; 12 is an amplifier; and 13 is an overvoltage protection circuit. That is, this device detects abnormal high voltage generated in the superconducting field winding 2 by connecting a protective high resistance 11 in parallel with the superconducting field winding 2, and amplifies the detection signal with an amplifier 12 to detect the overvoltage. The output of the protection circuit 13 controls the thyristor gate control device 5 to operate the thyristor excitation device 4 as an inverter. As a result, the energy due to the quench accident of the superconducting field winding that occurred on the DC side of the thyristor excitation device 4 is regenerated to the grid side, and the voltage of the superconducting field winding 2 rapidly decreases. Furthermore, abnormally large currents that occur simultaneously with abnormally high voltages can be cut off extremely quickly.

〔Effect of the invention〕

As explained above, according to the present invention, an abnormally high voltage generated in a field circuit including a superconducting field winding is detected, and the thyristor excitation device is thereby controlled to operate as an inverter. The energy from the quench accident of the superconducting field winding that occurred on the DC side of the device is regenerated to the grid side, rapidly reducing the abnormally high voltage in the superconducting field winding, and eliminating the field without destroying the superconducting field winding. By performing magnetic cutoff, the superconducting field winding can be reliably protected from abnormal high voltages associated with quench accidents.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram of a conventional rotating electric machine field circuit protection device, and FIG. 2 is a wiring diagram of a field circuit protection device of a superconducting rotating electric machine according to an embodiment of the present invention. 1...Synchronous generator, 2...Field winding, 3...Excitation transformer, 4...Thyristor excitation device, 5...
Thyristor gate control device, 11...protective high resistance, 12...amplifier, 13...overvoltage protection circuit.

Claims (1)

[Scope of Claims] 1. In a device that excites a superconducting field winding of a superconducting rotating electrical machine by a thyristor excitation device connected to a grid via a transformer, a field circuit including the superconducting field winding is generated in a field circuit including the superconducting field winding. 1. A field circuit protection device for a superconducting rotating electrical machine, comprising: means for detecting an abnormally high voltage caused by the abnormal high voltage; and means for controlling the thyristor excitation device to perform inverter operation based on the detection signal. 2. The field circuit protection device for a superconducting rotating electric machine according to claim 1, wherein the means for detecting the abnormal high voltage comprises a protective resistor connected in parallel with the superconducting field winding.