Unsynchronized Fault Location Based on the Negative-Sequence Voltage Magnitude for Double-Circuit Transmission Lines

This paper describes a new approach to fault location for double-circuit transmission lines based on only the voltage data of both ends of the faulted circuit. The ratio between the magnitudes of negative-sequence voltages measured at both ends of the faulted circuit is utilized to estimate the fault location. Since only the magnitudes are used, the data of both ends are not required to be synchronized, which removes any concern about data synchronization. Moreover, since only the voltage data are required, the errors caused by current transformers can be avoided. The proposed method can effectively locate the single-phase-to-ground, double-phase-to-ground, and phase-to-phase faults disregarding the fault resistance and prefault conditions and without any need for fault classification and phase selection. Unlike the iterative methods, the proposed method is fully analytical and does not cause much computing burden to the line relays. The accuracy and practicality of the proposed method make it an attractive function to implement in numerical relays.