Study of transient over voltage for insulation coordination in 220kV gas insulated substation

Abstract

The Gas Insulated Switchgear (GIS) substation has a high level of dependability and is simple to maintain. However, the specific issue with the GIS substation is the creation and spread of very fast transient overvoltage (VFTO) caused by the activation of circuit breakers, disconnector switches, or earth faults can put the insulation of equipment linked to the GIS under stress. This study covers the history of VFTO, its spread, and its effects on GIS. Power Systems Computer Aided Design (PSCAD) software is used to simulate various switching conditions. The results demonstrate that VFTO magnitudes are greater along the GIS bus nodes when the circuit breaker is activated than when the disconnector switch is activated. Switching transients influence equipment selection, protection, and tower air clearances. The two most common sources of transient overvoltage in power systems are lightning and switching. This work compares the modelling and simulation of a switching transient overvoltage investigation using PSCAD/EMTDC, a commonly used simulation tool. The purpose of the thesis is to provide modelling principles for the digital simulation of very fast transients (VFT) in gas insulated substations (GIS). Two lighting situations that may result in Fast Transient Overvoltages are analyzed and discussed: Direct Strike and Back Flashover. Overvoltages are unpredictably damaging to the electrical power grid. Overvoltages can be caused by a variety of factors, with lightning being one of the most hazardous. As a result, high voltage substation overvoltage protection is critical. To safeguard the substation as much as possible from the consequences of overvoltages, incorporate features that can help decrease these effects, such as surge arresters. The consequences of using surge arresters in a high voltage, gas SF6 insulated substation, as modelled in the PSCAD (Power Systems Computer Aided Design) program, are shown in this study