Factors affecting the VFTOS and Suppressing Techniques using Lumped Elements in UHV GIS Substations

Abstract

the suppression of very fast transient overvoltage (VFTOs) in a 1500 KV ultra-high voltage gas insulated substation (UHV GIS) using four different devices is presented in this paper VFTOs occur repeatedly during the operation of disconnector switches, due to the rapid propagation of travelling waves through the switchgear and the reduction of dielectric strength of substation components. This can cause flashovers to nearby grounded items because of transient ground potential rise or transient enclosure voltages. To address this, four techniques for suppressing VFTOs in a 1500KV UHV substation are presented, and the efficacy of these devices is assessed based on the peak value, rise time, and settling time of oscillations. The simulation is performed on a 1500KV substation using MATLAB/SIMULINK.