Geometric profile design effect on composite insulator performance in rainy climate using electrostatic field analysis

Abstract

Composite insulators have spread in the power grid replacing the old generation ceramic insulators. Their geometry can be modified to yield better electric field distribution. This reflects positively on the insulator water pollution performance preventing pollution flashover. In this work, the performance of twelve different designs of 33 kV composite insulator under rain pollution conditions is judged depending on analyzing the electric field distribution. The alternating fields, with frequencies above 1 Hz, are represented by electrostatic fields for most insulating materials. The approach utilizes the finite element method (FEM) based electrostatic field solver of COMSOL Multiphysics software. The performance of the different profile designs is compared systematically based on the reduction percentage of the field efficiency factor, and the selection went through three stages. Firstly, the performance of uniform profiles for the flat shed and inclined sheds were compared showing that the latter has a better electrostatic field distribution when polluted for both eight and ten shed profiles. Secondly, the performance of the uniform and alternating, with one and two small sheds, inclined profiles have been compared for both the eight and ten shed profiles. The results showed that the alternating profile with two small sheds has the better performance at rainy climate. Finally, for the performance of the alternating inclined two small sheds profile, the ten sheds profile design surpassed the other eight sheds design profile with 55.56 % of reduction percentage for the field efficiency factor in heavy rain (HR) and 33.33 % for light rain (LR) conditions.