Optimization of corona ring structure for UHV composite insulator using finite element method and PSO algorithm

The optimization method combining Finite Element Method (FEM) and particle swarm optimization (PSO) algorithm has been applied to design of corona ring structure for composite insulator used along Ultra High Voltage (UHV) transmission line in the present work. Firstly, corona discharges have been investigated by means of ultraviolet imager (UVI) observation which indicates improper corona structure and installation. Next, E-field distributions along composite insulator and on surface of corona ring have been computed and analyzed with three-dimensional FEM calculation model of UHV tangent tower on which hangs suspension and tension composite insulators in single-circuit transmission line using commercial software ANSYS. Finally, an objective function which can evaluate nonlinear relationship between maximum electric field strength and corona ring structure parameters has been established based on initial calculating results, On the other hand, PSO algorithm also has been implemented using APDL language in ANSYS computing environment, then optimization of corona ring structure for UHV composite insulator can be converted to seek minimum value of objective function utilized programmed PSO algorithm. The results show that the proposed optimization process can be conducted automatically and efficiently, moreover, the electric field strength along insulator and around corona rings after optimization is less than that before optimization, and the optimal rings improve electric field distribution along composite insulators.