Electric Field Optimization Of Composite Post Insulators Under Wet Condition

Rain flashover of composite post insulators plays an important role in UHVDC system operation.Shed structure and parameter are the important factors that effect rain flashover voltage.Based on the composite post insulators in Yunguang ±800kV Ultra-high Voltage Direct Current Project,composite post insulator with one-large-one-small shed and one-large-twosmall shed were modeled and analyzed in this paper.Orthogonal experiment design was used to select model parameter,and electric field distribution along insulator surface is simulated by ANSYS.The electric field of shed surface and the electric field of air gap were put forwards as the shed-optimization criterions.It further analyzed the effect of the shed distance,shed overhang and overhang difference on electric field distribution,and optimal insulator parameter was achieved to improve rain flashover characteristic.The results based on air-gap electric field are consistent with test results.Besides,based on insulator with one-large-one-small sheds structure,this paper studied the effect of the water-cut shed number and that of the water-cut shed overhang on electric field distribution under rain condition,showing that the water-cut shed number effect more greatly on air-gap electric field than the overhang.Furthermore,based on insulator with one-large-one-small sheds structure,this paper studied factors that affect the electric field distribution under rain condition such as insulator diameter,rainfall intensity and rain development.The influence of each factor on the electric field distribution of insulators is studied by using the electric field of shed surface and air gap.The research methods and simulation results in this paper provide support and reference for future artificial rain test on composite insulator.