Research on fault line selection in small-current neutral grounding power system

Abstract

A method of fault line selection was proposed based on fault grounded point transfer and wavelet transform in small-current neutral grounding system in this paper. Phase-separation vacuum circuit breaker was installed in the busbar and realize fault grounded point transfer through vacuum breaker of fault phase when single-phase-to-ground fault occurs. Thus zero-sequence current of fault line will change greatly but zero-sequence current of non-fault line had no significantly change. Zero-sequence current of each line before and after fault grounded point transfer was extracted by wavelet transform and achieved faulty line selection through the change of zero-sequence current. The method make use of the change of zero-sequence current to choose the fault line with high reliability, good performance in arc extinguishing and protect personal safety. Simulation results show that the method can exactly and effectively choose the fault line in small-current neutral grounding system.