The diagnostic method of earth fault based on the evolution of fault in distribution network

For power distribution systems, recognizing the single-phase ground fault is very difficult because there are several faults with similar features. This paper presents a novel method that can help to overcome this difficulty. The idea is that the evolution process of fault is a whole, which is composed of several evolution stages including the transient state, the stable state and others. Meanwhile it describes the evolution process of fault in the time domain and the frequency domain, and find out the characteristic processing in the evolution process of fault. In the same time, it divided the fault into several stages in which presented the evolution process statue of faults. In the characteristic processing, it analyzed the fault classification that caused the neutral point voltage increase, and verified the fault characteristic libraries. Theoretical analysis, computer simulation and lab experiments verified the effectiveness of the proposed method.