Mitigation/suppression techniques of very fast transient over voltages of a gas insulated substation

There are different switching operations takes place in the gas insulated substations (GIS). These switching operations generate the very fast transient overvoltages (VFTOs) which are dangerous to the substation equipments. Sometimes these transient overvoltages may cross the basic insulation level of gas insulated substation. Hence it is very important to mitigate these transient overvoltages. In this paper, the mitigation techniques of transient overvoltages have been discussed. These mitigation techniques have been compared to determine the effectiveness of these techniques. The simulation results shows that the VFTOs can be reduced upto 1 p.u. with the reduced level of oscillation frequency. The simulation work has been done using the PSCAD/EMTDC software.