A unified impedance-based fault location method for generalized distribution systems

Abstract

This paper proposes an extended and unified impedance-based fault location method which accounts for the inherent characteristics of distribution systems (unbalanced operation, presence of intermediate loads, laterals, and time-varying load profile). The technique is developed using phase-component analysis, and uses only local voltages and currents as input data. The time-varying load profile of distributions systems is considered by using an iterative procedure to update the load data used in the fault location algorithm. The procedure is based on matching both magnitude and angle of the prefault load impedance at the local terminal and the load impedance estimated through a power-flow analysis. In determining the equivalent power flow paths of branched distribution feeders a power-flow-based analysis is performed, enabling the technique to be applied in large distribution systems. Aiming to extend the application of the proposed method to underground in addition to overhead distribution systems, a set of generalized fault location equations which consider the shunt admittance of the lines was used. 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%.