An improved natural frequency based transmission line fault location method with full utilization of frequency spectrum information

Abstract

An improved natural frequency based method is proposed to accurately locate faults in transmission lines. The method only requires three phase instantaneous current measurements at the local terminal of the line and is compatible with protective relays using high-speed tripping techniques. First, the theoretical peak frequencies along the entire frequency spectrum of the measured currents are derived, for different fault types, locations and resistances. Next, the fault location is determined by finding the minimum average distance between the theoretical and the measured peak frequencies. Compared to the existing natural frequency based fault location methods, the proposed method solves the mode mixing problem during single phase to ground faults and systematically considers the effect of fault resistances. In addition, the proposed method fully utilizes the frequency spectrum information instead of only the dominant frequency, and therefore overcomes the difficulty to extract the dominant frequency. Numerical experiments have shown that, compared to the existing method, the proposed method presents much higher fault location accuracy during single phase to ground faults, and slightly higher (comparable) fault location accuracy for other types of faults, regardless of fault locations and fault resistances.