Optimal design of grading ring and analysis of electric field of 800 kV UHVDC bushing

In this paper, Finite Element Method is applied for the calculation of the electric field along the length of the HV bushing and also to optimize the design of grading ring added at the flange side. In the proposed method, 800 kV composite bushing is modeled using COMSOL Multiphysics 4.3 Software package which performs 2D simulation using Finite Element Method to investigate electric field distribution and the electric field behavior of the bushing is calculated with and without grading ring at the flange side. Without grading ring, the field intensity is higher at the shed, sheath and the joints of flange. A grading ring is employed at the flange side so as to reduce the field intensity and the location, configuration parameters of the grading ring are also analyzed for the optimal design and to limit the field intensity. Thus the optimized design is used to reduce the probability of occurrence of flashover across the bushing.