Discussion for fault phase selector on the weak-feedback side of transmission line

Although phase selectors of current-difference sudden-change component and current sequence component have been applied in digital HV transmission line protective system, they can′t work correctly in weak-feedback system owing to their own defects. Making use of simulating calculation with record data of one ground fault in a 220 kV weak-feedback system, this paper compares the performances of three fault component phase selectors, analyzes the problems that exist in identifying weak-feedback system at present. Based on theoretical analysis and simulating calculation, efficient method is presented to identify the weak-feedback system, and a scheme is put forward to resolve fault phase selection in these systems.