Optimization design of 500 kV double grading ring suspension composite insulator with ZnO microvaristor layers based on VSCSA

The use of microvaristor layers is an electric field control method for composite insulators. It can reduce the electric field stresses to prevent the extension of the composite insulator surface discharges and the complete flashover caused by the subsequent development of arcing. In order to improve the performance of composite insulators, a 500 kV double grading ring suspension composite insulator structure with ZnO microvaristor layers is proposed and optimized by Variable Step Crow Search Algorithm (VSCSA). A 2D axisymmetric simulation model is constructed by COMSOL, and then VSCSA is used to optimize the geometric dimensions of insulators, grading rings and microvaristors through the joint simulation of COMSOL and MATLAB. The electric field of composite insulators under clean and uniform contaminated conditions before and after optimization is studied. The results show that the optimized design can reduce the electric field strength of composite insulators under clean and uniform contaminated conditions. It is also proved that the injection of ZnO microvaristor layers into the double grading ring suspension composite insulator can improve the performance of the insulator. The research provides a new method for the design and optimization of high voltage composite insulators, which is of great significance.