Study on dynamic flashover model of ice-covered insulator string

To simulate the special state of ice-covered insulators, the traditional circuit model for insulators flashover was improved by considering the influence of air gaps. Take the energy varying accompany the ice-melting and water vapor into account, Cassie and Mayr differential equations were combined to describe the arc resistance. Based on the dynamic equations of arc resistance and residual ice-layer resistance, the dynamic flashover model of ice-covered insulators was set up. The measured voltage and current on the ice-covered insulators when flashover occurred were approximated as the arc voltage and arc current, which supplied base date to calculated the model parameters using nonlinear least squares method. Thus, the dynamic variations of arc voltage and current from arc generated to flashover on the ice-covered insulators can be simulated. The simulation results have been compared with the experimental results, which validate the presented dynamic flashover model.