Use of Particle Swarm Optimization in the computation of an optimal permittivity distribution in functionally graded material insulators

Functionally graded materials (FGM) are materials in which one or several material properties vary continuously as a function of space. In this work, optimized spatial distribution of dielectric permittivity is obtained with the objective of efficient electric stress control. This is of significance to solid insulators like spacers for GIS (Gas Insulated Switchgears), bushings, cable terminations, winding insulation, etc. In order to optimize the permittivity distribution of an FGM, a bi-objective particle swarm optimization (PSO) technique is used. The two objectives of the problem are (i) to reduce the maximum electric field in and around the solid insulator and (ii) to reduce the non uniformity in the electric stress distribution within the insulator.