Single-Line-to-Ground Fault Location in Resonant Grounded Systems Based on Fault Distortions

Under single-line-to-ground (SLG) faults, the voltages and currents in resonant grounded systems will inevitably be distorted. To locate the faults quickly and accurately, this paper proposes a location method based on fault distortions. The faulty phase is firstly detected according to the first SLG fault feature below, and then the faulty feeder and section are detected according to the second feature below. 1) On the bus, one of the following distortions occurs. One dropped faulty-phase voltage (FPV) and two raised normal-phase voltages (NPVs). One dropped FPV and two NPVs (in which one rises and the other drops), where the product of FPV amplitude distortion and its phase-angle distortion is unique among three phase voltages. 2) On the faulty phase, the current on faulty feeder upstream rises, while the currents on faulty feeder downstream and normal feeders drop. Compared to existing methods, simulation tests show that the proposed method is robust under high impedance faults, and has a simple algorithm and easy engineering implementation. Also, it is effective under harmonics, three-phase imbalance, and different fault positions.