Faulty feeder identification under high impedance faults for flexible grounding distribution system based on leakage resistance identification

Abstract

To address the challenge of identifying faulty feeder in the case of high impedance faults (HIF) within a flexible grounding system that employs parallel small resistance (PSR) from the arc suppression coil, this paper proposes a method for faulty feeder identification based on leakage resistance identification. Initially, the paper analyzes the variation characteristics of the equivalent resistance to ground (ERG), while taking into consideration the leakage resistance in the distribution line. For the healthy feeder, the ERG is always equal to its leakage resistance. In contrast, for a faulty feeder, the ERG is determined by paralleling the leakage resistances of all healthy feeders before the PSR is put into use, However, it becomes approximately three times greater than the neutral resistance once the PSR is in use. Subsequently, the ERG of each feeder is fitted using the least squares method, and a scheme for identifying faulty feeders is constructed. The effectiveness of this proposed method is ultimately validated through PSCAD simulations and field recording data, demonstrating that the transition resistance can reach up to 5000Ω, which is anticipated to enhance the performance of protection for single-phase-to-ground fault (SPGF).