Configuration Principle of Generator Relay Protection Device

Today Starlight Power Generator manufacturer shares the configuration principle of generator relay protection device. Hope it is helpful to you.

1.Longitudinal differential protection shall be installed for the short circuit between the stator winding and its outgoing line of generators above 1MW.

2.For the single-phase ground fault of the generator stator winding directly connected to the bus, when the ground capacitance current of generator voltage network is greater than or equal to 5A (without considering the compensation effect of arc suppression coil), the zero sequence current protection acting on the trip shall be installed; when the ground capacitance current is less than 5A, the ground protection acting on the signal shall be installed.

For the generator transformer unit, it is generally installed at the voltage side of the generator as the grounding protection for signals. When the grounding capacitance current at the voltage side of the generator is greater than 5A, arc suppression coil shall be installed.

For generators with capacity of 100MW and above, stator grounding protection with protection zone of 100% shall be installed.

3.For inter turn short circuit of generator stator winding, when the winding is connected to star and there are parallel branches in each phase, there is no single relay type transverse differential protection in the building.

4.For overcurrent caused by external short circuit of generator, the following protection methods can be adopted:

(1)Negative sequence over-current and single-phase low-voltage start over-current protection are generally used for power generation of 50MW and above.

(2)Compound voltage (negative sequence voltage and line voltage) enables 1-acting over-current protection;

(3)Over current protection is for small generators up to 1MW.

5.For negative sequence overcurrent caused by asymmetric load or external asymmetric short circuit, negative sequence current protection is generally installed on 50MW and above 50MW generators.

6.For the overcurrent of generator stator winding caused by symmetrical load, it shall be installed in the overload protection of one phase current.

7.For the over-voltage of hydrogenerator stator winding, over-voltage protection with time delay shall be installed.

8.For wiring failure of generator excitation circuit

(1)The hydrogenerator is generally equipped with one point grounding protection, and the small capacity unit can adopt the regular detection device.

(2)For the one-point grounding of the excitation circuit of the turbocharged generator, the regular detection device is generally adopted, and for the large capacity unit, the one-point grounding protection can be installed. For two-point grounding fault, two-point grounding protection shall be installed and put into operation after one-point grounding of excitation circuit.

9.For the generator excitation loss fault, when the generator does not allow loss of excitation operation, the circuit breaker of the development motor shall be interlocked when the automatic deexcitation switch is disconnected; for the generator with semiconductor excitation and 100MW or above using motor excitation, a special loss of excitation protection shall be added to directly reflect the change of electrical parameters when the generator loses excitation.

10.For the overload of rotor circuit, the generator with 100MW or above and semiconductor excitation system shall be equipped with rotor overload protection.

11.For the sudden closure of the main steam valve of the steam turbine generator, in order to prevent damage to the steam turbine, reverse power protection can be considered for the large capacity generator set.

12.Other protection: If the power system oscillation affects the safe operation of the unit, the out of step protection should be installed on the 300MW unit; if the low frequency operation of the turbine will cause mechanical vibration and blade damage, which will cause great harm to the turbine, the low-frequency protection can be installed; when the water-cooled generator is cut off, the water-cut protection can be installed.

In order to eliminate the internal faults of the generator quickly, when the protection acts on the tripping of the generator circuit breaker, it must also act on the automatic deexcitation switch to cut off the excitation circuit of the development motor, so that the electromotive force is no longer induced in the stator winding and the short-circuit current is continuously supplied.

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