A combined phase selector element based on the superimposed sequence components for parallel lines on the same tower

The traditional fault phase selectors which have excellent performance for single-circuit transmission line may mis-operation for some cross country faults in parallel lines on the same tower. Based on the analysis of faults in parallel lines, a novel combined phase selector based on the one-end sampling data of a single line is proposed. Assume that parallel lines as the overall analysis of the object, the sequence voltages are employed to determine the fault phase. The relationship between the superimposed positive- and negative- sequence impedances are employed to determine that the fault occurs either in line I or line II. According to the phase selector, the phase selection can be achieved in parallel lines on the same tower, especially in cross country faults. Therefore, the distance relay can be achieved using appropriate equations depending upon the faulted phase identification. Simulation results show that the proposed scheme is well suited for the phase selection in parallel transmission lines.