A Phase Selection Element for High Resistance Ground Faults of Transmission Line

Zero sequence current differential protection can't select fault phase of transmission line. Normal phase selection element is affected by load current and fault resistance, especially high resistance ground faults. A new phase selection method is proposed in this paper. For high resistance single-phase-to-ground faults, sequence components of fault phase at fault point are equal and not impacted by fault resistance. This characteristic is used to identify fault phase of high resistance ground faults. The new phase selection is not impacted by load current. Simulation results proved its effectiveness.