Fault location of two-parallel transmission line for non-earth fault usingone-terminal data

An accurate fault-location algorithm for two-parallel transmission line of direct ground neutral system is presented. The algorithm employs the faulte d circuit and healthy circuit of two-parallel line as fault-location model, in which remote source impedance is not involved. It effectively eliminate s the effect of load flow and fault resistance on the accuracy of fault loc ation. It embodies an accurate location by measuring only one local end dat a and it is used in a procedure that provides the automatic determination o f fault types and phases, rather than requires engineer to specify them. Si mulation results have shown the effectiveness of the algorithm under the co nditions of non-earth fault (phase-to-phase fault and three-phase fault wit h and without earth-connection).