A novel fault line selection algorithm of single-phase ground faults in ungrounded neutral system using wavelets transform

Most faults in ungrounded neutral systems are single-phase earthing. Because of the influence of arcing and operating manners, the accuracy of fault line selection algorithms using steady zero sequence current is not satisfactory. In this paper, the effects of arcing on the accuracy of fault line selection are detailed after studying the zero-sequence current during arcing faults. The Clarke transform is employed and the wavelets transform is also adopted to develop a novel method for fault line selection. EMTP is employed to simulating the arcing faults and the simulation is performed under various sampling frequencies and A/D resolution. The results show that the novel method is valid, effective and robust.