Fault location for multiple circuit overhead lines of different voltage grade on the same tower

Based on distributed parameter model,an accurate fault location algorithm for multiple-circuit overhead lines of different voltage grade on same tower is described.By using the positive sequence component of voltage and current synchronously sampled at both terminals,the positive-sequence voltage of fault point can be deduced from both terminal based on uniform transmission line equations,then the fault location equation can be got.This principle can eliminate the effect of zero-sequence mutual inductance between coupling lines.Theoretically,the proposed algorithm is independent of source impedance,fault resistance,shunt capacitance and fault types.This method solves the problem of accurate fault location for multiple-circuit overhead lines of different voltage grade on the same tower.Simulations show that the proposed fault location method has a satisfactory precision and are free from the influence of resistance and fault types.