Transmission line fault location for double phase-to-earth fault on non-direct-ground neutral system

An accurate algorithm for locating double phase-to-earth fault on transmiss ion line of nondirect ground neutral system is presented. The algorithm emp loys the faulted phase network and zero-sequence network as the fault locat ion model. It effectively eliminates the effect of load flow and fault resi stance on the accuracy of fault location. The technique embodies an accurat e location by measuring only one local end data. The algorithm is used in a procedure that provides the automatic determination of faulted line and ph ase, rather than requires engineer to specify them. Simulation results have shown the effectiveness of the algorithm under the condition of earth faul ts.