Locating of Multi-phase Faults of Ungrounded Distribution System

This paper proposes a new method for locating multi-phase faults in ungrounded distribution systems, including phase-to-phase faults, double-phase-to-ground faults, and three-phase faults. Through identification of the faulty feeder section, the fault location algorithm is only implemented on the faulty section of the feeder, thus avoiding the unnecessary computations. A two-ended fault location algorithm is implemented for both two and three phase faults on the mainline of the faulty section. Two different one-ended fault location algorithms are also implemented for handling two-phase faults and three-phase faults on the laterals of the faulty section respectively. The proposed fault location algorithms make no assumption regarding the fault impedance, thus estimation of fault location is invariant to fault impedances. Numerical examples are given to demonstrate the effectiveness of the proposed method.