Faulty feeder detection for single-phase-to-ground fault in resonant grounding system based on transition resistance estimation

Aiming at the weak fault characteristics and poor adaptability of existing methods during high-impedance faults in 10 kV resonant grounding distribution systems, this paper proposes a fault detection method based on transition resistance estimation. Firstly, transient equivalent models of faulty and healthy feeders are constructed by using lumped parameters, and voltage-current matrix equations are obtained. Secondly, by analyzing the differences in the phase-frequency characteristics between lumped parameter model and distributed parameter model, the characteristic frequency band of each feeder is determined. Finally, the transition resistance value of each feeder is estimated by using the nonlinear least squares method, and thus the fault detection criterion is constructed. Specifically, if the transition resistance values of all feeders are greater than 10000Ω, it is determined as a bus fault. Conversely, the feeder corresponding to the minimum value is identified as faulty feeder. Simulation results and field tests show that it can accurately achieve fault detection in high-impedance faults and even complex grounding scenarios.