The Study About The Optimization Of Grading Ring Structure Of EHV Composite Insulator

At present, with more and more composite insulators used in service, there emerged many problems. The partial discharge and premature aging resulting from too high electric field in insulators are familiar problems. So it is necessary to have an electric analysis for studying and optimizing the grading rings structure of composite insulators.Having summarized the calculation methods of electric field, this paper selects the combination of FEM and BEM according to the features of composite insulator. In light of fact that both FEM and BEM have different characters and they are complementary to each other, an iterative method is developed by combining the two methods using domain decomposition method, which combines the merits of both and keeps each other's individuality. FEM makes use of the FEMLab software. At the end, we confirmed the feasibility and veracity of this iterative calculation method by resolving a three-dimension calculation example of 220kV line composite insulator.The research of optimization techniques now focuses on two main branches: the stochastic and the detective methods. The stochastic search procedure is to find the global optimal by millions and millions FEM calculation and proves unbearably time expensive; the detective search procedure is to find the optimal by the search direction, but sometimes falls into the local optimal and can not escape by itself. To solve above problems, a new method has been created in this paper: to optimize the grading ring structure of composite insulator by using ANN theory. So time cost decreases dramatically.