Electric field calculation and grading ring optimization for 1000 kV AC post porcelain insulator

Grading ring design is an important step in the post porcelain insulator design process, appropriate grading ring configuration can improve the electric field distribution of post insulators and extend the service life. In this paper, a static 3-D model of 1000 kV AC post porcelain insulator was established by using a finite element method (FEM) analysis software ANSYS. The calculation results of electric field distribution along the insulator were presented. The effect of grading ring structure to the electric field distribution of the post porcelain insulator was analyzed and a use of double ring configuration at the conductor side of the insulator is beneficial. Therefore, Artificial Fish Swarm Algorithm (AFSA) was applied to optimize the dimensions and location of grading rings, then the maximum electric field magnitudes on the surfaces of grading rings, flange and insulator sheds were compared and appropriate parameters of grading rings were recommended finally. The achievements of this paper have been successfully applied on the 1000 kV ultra-high voltage (UHV) pilot project in China and it was proved very effective by field observations with an ultraviolet camera.