A Review on Transient Analysis in Gas Insulated Substations

Gas insulated substation (GIS) is an indoor high voltage substation and the insulating medium used is SF6 gas. The main advantage of GIS is it requires only about 10 % area of normal substations. When lightning strikes near substations or due to disconnector operations in GIS high frequency surges called VFT (very fast transients) are produced. The basic insulation level (BIL) ratio of ultrahigh voltage (UHV) is less compared to lower voltage substations.Therefore proper modelling of VFTO (Very Fast Transient Overvoltage) is necessary to ensure safety. Here modelling of VFTO as well as GIS substation components are to be carried out. By proper modelling and testing the efficiency and safety of the system can be ensured.