Extended impedance-based fault location formulation for unbalanced underground distribution systems

Underground distribution systems are commonly exposed to permanent faults. Due to specific construction characteristics, visual inspection for fault location cannot be performed. To overcome this limitation, accurate fault location techniques must be applied. In this paper, an extended impedance-based fault location formulation for unbalanced underground distribution systems is described considering single line-to-ground faults. The technique uses only local voltages and currents as input data. An iterative algorithm for cable capacitive current compensation in the fault location formulation is proposed. The formulation focuses an easily practical implementation and is based on typical available systempsilas data, as lines impedance and admittance matrices, and also system loads. Test simulations on a real data underground distribution system demonstrate the proposed extensions improvements. The algorithm performance presents negligible fault resistance, distance, and inception angle variation effects.