Impedance-based fault location for overhead and underground distribution systems

This paper presents an extended formulation for fault location on electric distribution systems based on one-terminal measurement of apparent impedance. The method is developed using phase-components analysis to account for the inherent unbalanced operation of distribution feeders. Since distribution loads present a stochastic variation through time, a technique for compensation of load variation in both magnitude and angle is also presented. The proposed developments include two general fault location equations that account for any fault type. An iterative algorithm to compensate the line capacitive current component is also provided, thus enabling the application of the technique to long rural and underground systems, in addition to overhead distribution systems. Test results show the accuracy and robustness of the fault location algorithm to different fault types, distances and resistances, considering system´s load profile variations up to ± 50%.