Single phase grounding fault detection and section location method based on non power frequency signal injection

Abstract

Aiming at the problem of detection and location of existing distribution automation terminals under the condition of high resistance ground fault in resonant grounded distribution network, this paper proposes a single-phase ground fault detection and section location method based on non power frequency signal injection. Based on the permanent grounding fault of distribution network, firstly, the active flexible grounding device is used to inject the small signal of non power frequency characteristic current into the neutral point of distribution network, and the non power frequency current amplitude is extracted through the detection of distribution automation terminal on the fault feeder. According to the difference of non power frequency characteristic current amplitude between normal and fault areas, a fault location criterion based on the ratio of section current to threshold amplitude is proposed to realize the accurate location of fault areas. The influence of injection signal parameters on ground fault detection and location methods is further analyzed, and the injection size and optimal frequency band of non power frequency signal are selected. The simulation results show that this method has strong resistance to high resistance and high accuracy, and can realize the accurate location of fault section under a wide range of grounding resistance.