Method for removing instantaneous short circuit earth faults of direct current line of flexible direct current power transmission system

Abstract

The invention relates to a method for removing instantaneous short circuit earth faults of a direct current line of a flexible direct current power transmission system, and belongs to the technical field of power electronics. Requirements of an electric power system on the fault removing capability of the flexible direct current power transmission system is considered. By means of the structural characteristics of the flexible direct current power transmission system and the characteristic that an ac circuit breaker can break a direct current the magnitude of which is lower than a certain scope, the ac circuit breaker is connected in series between a converter transformer neutral point and an earth resistor, and plays a role in breaking direct current fault currents. By employing the ac circuit breaker, the problem that the whole flexible direct current power transmission system needs to be shut down in order to remove instantaneous short circuit earth faults of the direct current line is solved. The method is advantaged by being economic and reliable, and being mature in technology, simple to implement and excellent in performance, and can be applied to practical engineering of flexible direct current power transmission.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a method for removing an instantaneous short-circuit grounding fault of a DC line of a flexible DC power transmission system. Background technique [0002] After a short-circuit fault occurs in a component in the power system, the fault current is generally cut off by a circuit breaker connected in series at both ends of the faulty component, so as to realize the extinguishment of the arc at the fault point. In the AC system, the current cycle has two natural zero-crossing points, and the AC circuit breaker makes full use of this opportunity to extinguish the arc and complete the medium recovery. However, there is no natural zero-crossing point in the DC system. Therefore, it is much more difficult to break the DC line. The first task of breaking the DC line is to extinguish the arc. Secondly, due to the existence of the inductance in the DC system, a large ...

AI Technical Summary

Problems solved by technology

[0012] The purpose of the present invention is to provide a method for cutting the instantaneous short-circuit ground fault of the DC line of the flexible direct current transmission system, which aims at the problem that the entire system needs to be shut down when removing the instantaneous short-circuit ground fault of the DC line of the flexible direct current transmission system. Through the AC circuit breaker and simple sequential operation, the function of cutting off the fault current of the DC line that is traditionally considered to be required by the DC circuit breaker can be realized, and the DC line of the flexible DC transmission system can be realized without affecting the normal operation of the entire flexible DC transmission system. Removal of Instantaneous Short-Circuit Grounding Fault

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