Fault location of two-parallel transmission line for nonearth fault using one-terminal data

An accurate fault-location algorithm for two-parallel transmission line of direct ground neutral system is presented. The algorithm employs the faulted circuit and healthy circuit of a two-parallel transmission line as a fault-location model, in which remote source impedance is not involved. It effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. It embodies an accurate location by measuring only one local end data and it is used in a procedure that provides the automatic determination of fault types and phases, rather than requiring an engineer to specify them. Simulation results have shown the effectiveness of the algorithm under the conditions of nonearth fault (phase-to-phase fault and three-phase fault with and without earth-connection).