Fault phase selector of protective relay for cross country fault on double circuit lines

Aiming at the misoperation of the conventional phase selector by phase current-differential during some cross country faults, a fault phase selector for double circuit lines on the same tower using fault superimposed components direction element is developed, where the cross country fault of double circuit lines is considered as multiple faults of single circuit lines to analyze the misoperation of conventional phase selector. The new scheme selects fault phase by fault superimposed component voltage, and the fault lines of the corresponding fault phase are selected with fault superimposed component direction element. If the phase angle between faults superimposed component voltage and current of either double circuit line is in the range of 0°~180°, the fault is in the line. The EMTP simulation results show that the proposed scheme is applicable to microcomputer-based protection.