Repeated Strike Process Modeling of Very Fast Transient Overvoltage Induced by Disconnector Switch Operation in 252kV GIS

Abstract

It is a problem that the existing very fast transient overvoltage (VFTO) repeated strike simulation model doesn't take strike characteristics of the contact gap into account and the arc resistance model can not fully reflect the dynamic changes of the arc. Firstly, a 252 kV GIS experiment platform is established to obtain strike characteristics by closing/opening disconnector. Secondly, considering peak value of current, length of contact gap and air pressure, combined with the arc extinction law of special fast transient overcurrent (VFTC), a double exponential high frequency arc resistance model is proposed. Finally, based on the discharge voltage curve and arc resistance model, the whole-process VFTO simulation model of 252kV GIS is established. Variable step method is used to alternate calculations of the power-frequency steady process and high-frequency transient process to obtain an efficient and accurate simulation.