A Novel Arc Model for Very Fast Transient Overvoltage Simulation in a 252-kV Gas-Insulated Switchgear

One of the important issues of concerns for gas-insulated switchgear (GIS) is the generation of very fast transient overvoltage (VFTO) during switching operations, especially at operational voltage levels of 330 kV and beyond. It becomes extremely important to build an arc model for VFTO simulation, since the arc determines VFTO characteristics to a great extent. However, existing arc models for VFTO simulation are too simple to provide simulation results that agree well with the experimental ones. As the arc resistance is often taken as a function of the very fast transient current (VFTC), it is necessary to get the experimental data on the VFTC. Therefore, a 252-kV GIS platform has been built as well as the VFTO and VFTC measuring system. On the basis of the experimental investigation, a novel arc model for VFTO simulation was proposed, in which the time dependent characteristics of the arc resistance is revealed. The model may be used for VFTO simulation for extra high voltage or ultrahigh voltage GIS.