Analysis and detection of high impedance grounding fault in neutral point effectively grounding distribution network

Abstract

The neutral point effectively grounding mode with small resistor can suppress transient over-voltage and solve faulty line selection problems during single phase earth faults in distribution system so that it has been increasingly applied in urban distribution systems and large mining industry grids. High impedance grounding faults (HIGFs) which exhibit too low fault currents to be identified by over-current protection, however, often occur in effectively grounding distribution systems. HIGF characteristics have been studied in detail and a Mayr function based arc model is introduced to simulate HIGFs, with its accuracy being testified by field data. As for existing method which uses frequency domain characteristics to detect HIGF has low success rate, a HIGF detection method is developed based on zero-sequence current distortion with convex and concave characteristics. Simulation and recorded field data have verified higher sensitivity and reliability of the proposed algorithm. © 2013 State Grid Electric Power Research Institute Press.