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 faults on transmission lines of nondirect ground neutral systems is presented. The algorithm employs the faulted phase network and zero-sequence network as the fault location model. It effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The technique embodies an accurate location by measuring only one local end data. The algorithm is used in a procedure that provides the automatic determination of faulted line and phase, rather than requires engineer to specify them. Simulation results have shown the effectiveness of the algorithm under the condition of earth faults.