Arc Grounding Model And Simulation In Non-effectively Grounded System

Currently, eighty percent of network faults appear in our distribution are single-phase ground fault. Among the single-phase ground faults, arc intermittent ground faults harm worst. In the neutral non-effective grounding system, network allowed to run two hours with faults if single-phase ground fault happens. But if arc grounding fault happens, due to the instability of arc, high-frequency component will happens in the system, which will threat the system operation safety.Due to the instability of arc status, mathematical model of arc is hard to establish. And the studies of simulation model of the arc grounding are quite a few. This paper mainly focused on the analysis of arc grounding process and proposed a new method theoretically to judge when and whether the arc should extinguish or renew. There are two processes in current zero off period of arc:thermal breakdown and electrical breakdown. A new method was proposed that based on Mayr and Cassie model to simulate those two progresses which can provide a theoretical basis for the arc extinguishing or renewed.And a simulation of arc model was built using transient simulation tools PSCAD. The simulation results contains many forms of arc waveforrm. After that, the simulation results were compared with theoretical analysis results to verify the correctness of the model.According to the distribution network "Bei Men Yi Xian" in Jining Shandong province, a distribution network simulation model was established. The model parameters was set up according to the actual system parameter. And this model was used to analyze the effect of arc grounding fault and switch operation by simulation. The faults and the switch was set up nearby bus and at the end of line. At last the danger points was obtained according to the voltage and current changes of all the 38 monitoring points in the system.This model was used to analyze the role of Petersen coil in reducing the resonance overvoltage and harmonics caused by arc grounding faults. And one new methods is put forward to suppress arc grounding over-voltage:Transforming arc grounding fault into direct ground fault. When the arc grounding fault turn in to direct ground fault, the arc can be extinguished effectively. And two hours was left for staff member to exclude accident, because the system can running with fault for two hours in the non-effectively grounded system.