Developed optimization technique used for the distribution of U-shaped permittivity for cone type spacer in GIS

Abstract The solid/gas interface formed by solid spacer and insulating gas represents the weakest point in gas insulated systems (GIS) which is due to field intensification on spacer surface especially near triple junctions (Solid insulator – Gas – Electrodes) at HV and ground electrodes. Functionally Graded Material (FGM) is applied to the spacer design instead of uniform distribution to improve the electric field distribution across the spacer surface without changing its simple profile. Cone spacer model with uniform and FGM permittivity distribution has been introduced to study the effect of FGM in improving the electric field characteristics along spacer surface and near triple junctions. The verification of the proposed model has been investigated by comparing the obtained simulation results of the field to these given by others. Developed computerized optimization technique for automatic U-shape permittivity distribution is presented. U-shape permittivity distribution is used to mitigate the electric field strength not only near HV triple junction (Solid insulator – Gas – HV electrode) but also near ground triple junction (Solid insulator – Gas – Ground electrode). The simulation of the electric field is presented by the concept of Finite Element Method (FEM) using Comsol Multiphysics software. The optimization algorithm is programmed using Comsol LiveLink™ for MATLAB.