Simulation of Arc Grounding Over-Voltage Based on MODELS and TACS for Neutral Isolated Systems

Arc grounding over-voltage is one of the worst over-voltages in the neutral isolated system. It is an important factor to be considered when selecting neutral ground mode. At present, system simulation is the main method for the study of the arc grounding over-voltage. Arc extinguish and re-ignition is simulated by controlling the switch on or off. However, the switch opening or closing need to be controlled by the manually preset timer, according to the principle that arc re-ignites for every other power frequency cycle or half power frequency cycle. In fact, arc re-ignition may not occur at the maximum recovery voltage of the faulted phase because of the statistical property of arc occurring. For this reason, the simulation model based on the fixed timer controlled switch is not accurate. In addition, the timer for the switch opening or closing is needed to be reset every time when the system operating mode changes. This process is very complex so timer controlled model is difficult to apply in practice. In the light of the above, a new simulation model is proposed in this paper, which is based on a comprehensive study of the mechanism of the generation of arc grounding voltage. Transient analysis of control system using the TACS and MODELS modules of EMTP is employed to study and design the control section of the switch. The control program is compiled by the special language of MODELS module. There is no need to set the opening and closing time of the switch. This simulation model offers flexible operation and is more close to the actual situation. Desirable results are achieved when applied to study the arc grounding over-voltage in 10kV neutral isolated system. Simulation results from EMTP verify the correctness of this model, which also have a great potential for practical applications.