Study on the flexible arc elimination method for grounding fault of distribution network based on single-phase cascade H bridge

Abstract

All 10kV distribution network systems in China adopt non-effective grounding. With the expansion of distribution network scale, the earth fault current and the harmonic content increases. The earth fault arc difficult extinguish by itself. The traditional circuit breaker technology for failover to the substation may cause the potential to rise in the station. In this paper, A voltage arc extinction method for the combination of single-phase cascade H-bridge converter and vacuum circuit breaker is proposed. Three single-phase vacuum circuit breakers are respectively connected to A, B and C phases. When the fault occurs, the closed corresponding circuit breaker is connected to the ground fault for transfer. A double closed-loop control system is constructed to track the ground fault current in real time based on the deadbeat control method, so as to realize the full compensation of ground fault current and eliminate the ground potential rise. Through RT-Lab simulation platform, a 10kV distribution network model was built. The arc extinction method proposed in this paper was simulated and analyzed different resistance grounding. It was verified that it could effectively suppress arc light grounding fault and solve the problem that the traditional failover device could not flexibly control zero-sequence current.