Study On Electric Field Distribution Optimization Of Composite Insulator With Series Connection Of Glass Insulator

Due to the geometry configure of composite insulator, fitting structure and dielectric properties of silicone rubber material, the two metal electrodes bring high electric field area near the ends of the composite insulator. With the increase of the potential lever and the length of composite insulator, the electric field becomes higher near the ends. High electric field will cause partial discharge on the insulation material and the surface of the metal electrodes, and impacting the operating characteristics of electromagnetic environment and insulating material. So the high electric field is a dangerous enemy to the safe operation of the power systems. Therefore, it is significant to study the new method of improve the electric field and potential distribution.At present, the installation of corona rings is commonly used as the pressure balancing measure for composite insulators. Corona rings have an obvious effect on improving electric field distribution of composite insulator ends, but limited effect on improving overall voltage distribution. However, the installation of corona rings will reduce the dry arcing distance between two poles of composite insulators, and lower the lightning withstand level of transmission lines. And at the same time both at home and abroad there is still no uniform standard for the use of corona rings.Based on the finite element method, taking the combined use of composite insulators and glass insulators as an example, this thesis puts forward a new method to improve the electric field distribution of composite insulators. This thesis esTablelish a three-dimensional electric field calculation model of composite insulators in the transmission line, and then studied the improved situation of surface potential and electric field distribution of composite insulators with glass insulators installed in the high voltage side of composite insulators at different levels of voltage. The results show that by this means, the voltage that the conducting wire side of composite insulators can withstand is lowered; distorted electric field is eliminated; the electric field distribution in the ends of composite insulators improved. Finally, this thesis recommends the number of glass insulators which should be installed in the high voltage side of composite insulators at different levels.According to the test result of 110kV composite insulator carried in the artificial fog chamber, the result shows that the flashover voltage is obviously improved and the voltage gradient is litter changed after series connection glass insulator. This is due to the pressure effect of glass insulator and the flashover arcing is inhibited certainly. 220kV and 500kV composite insulator can take this as a reference. At last, taking the combined use of 110kV composite insulators and glass insulators as an example, creepage distance, windage yaw, lighting withstand level and the affection of iced-covered composite insulator are studied. It offers some help for insulator modification and external insulation design of transmission lines.