Flexible grounding system grounding fault protection method based on fault phase voltage polarization

Abstract

A flexible grounding system grounding fault protection method based on fault phase voltage polarization uses fault information of the whole process before and after parallel resistor input, realizes selection of a fault phase in an arc suppression coil compensation stage, and adopts definite time limit zero sequence current protection and zero sequence current out-of-limit action when transition resistance is small. When the transition resistance is high and the zero-sequence voltage is small, the fault phase voltage is used as the polarization of the zero-sequence voltage and the phase ratio of the zero-sequence voltage to the zero-sequence current, the problem that the precision of the zero-sequence voltage transformer is insufficient during high-resistance grounding is effectively avoided, and compared with a traditional zero-sequence over-current protection method, the transition resistance tolerance capacity of the zero-sequence over-current protection method is remarkably improved. According to the method, different measures are taken for an instantaneous grounding fault and a permanent grounding fault in single-phase grounding, so that rapid and accurate isolation of the permanent grounding fault is ensured, further expansion of an accident caused by long-term existence of power frequency overvoltage of a system is avoided, and the instantaneous grounding fault can be compensated to disappear automatically without tripping.

Description

technical field [0001] The invention relates to the field of distribution network fault detection and protection, in particular to a ground fault protection method for a flexible grounding system based on a fault phase voltage polarization. Background technique [0002] Ground fault processing technology of arc suppression coil connected in parallel with small resistance grounded distribution network: for transient faults, arc suppression coil is used for arc suppression; for low resistance intermittent faults and permanent faults, parallel resistance is used to increase fault residual current and achieve rapid Line selection, positioning and segment isolation. According to the size of the parallel resistance, the parallel small resistance grounding system of the arc suppression coil is divided into two ways: parallel medium resistance and parallel small resistance. The parallel resistance is an auxiliary means to solve the fault protection problem of the resonant grounding...

AI Technical Summary

Problems solved by technology

However, the understanding of its ground fault process and fault characteristics is still not comprehensive at present. The protection methods of the existing small resistance grounding system or small current grounding system cannot be directly applied, and there are risks of false operation and refusal to operate. It is urgent to study special protection methods. And improve the sensitivity of the protection when the high resistance is grounded

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