Analysis And Simulation Research Of Single-Phase Arc Grounding Fault In Small Current Grounding Power Systems

The neutral grounding mode of power systems is variable. The small current grounding modes such as isolated neutral mode and neutral grounding via arc suppression coil mode are mainly adopted in medium voltage distribution networks in China. The single-phase arc grounding fault is the main fault form in medium voltage distribution networks. At present, single-phase grounding fault is usually regarded as metallic grounding fault or grounding via a fixed resistance in simulation. For arc grounding fault, using the above-mentioned simulation model, the results can not accurately reflect the actual situation. It is essential to build an accurate grounding arc model for fault analysis.In this paper, several existing arc models were compared and a grounding arc model was built based on the dynamic arc model which was built based on the existing models. And then the model of 10kV distribution networks and the arcing fault model were established upon the PSCAD. Comparing the simulation waveform with the experimental waveform, the results show that this model can reflect the characters of arc grounding fault effectively. Using this model to simulated the several different intermittent arc grounding faults, their over-voltage multiple was tally with the actual situation, which proved the validity of the arc fault model indirectly. For different kinds of arc suppression coil, this paper evaluated their arc extinguishing ability during the single-phase arc grounding fault via different evaluation index. At last, this paper proposed a new method to distinguish the arcing fault based on the fundamental component of the fault voltage steady waveform. Cooperate with the method which based on the phase angle difference between the neutral voltage and the phase voltage, different types of grounding fault can be identified. The effectiveness and correctness of this identification method was proved by simulation on PSCAD and experiment on 10kV network. The work in this paper laid a foundation of further study on the single-phase grounding fault in small current grounding system.