Research On Electric Field Distribution And Creeping Discharge Characteristics Of Contaminated Insulator Strings

Affected by the actual operating environment,the degree of pollution and aging on the surface of the insulator is different.The change of the surface condition of the polluted insulator will affect the discharge conditions on the surface of the insulator,which will cause the change of the discharge characteristics of the insulator and make the pollution flashover discharge rule of the insulator more stable.It is complicated,and pollution flashovers lead to large-scale power outages that still occur frequently.Therefore,it is of great significance to study the discharge characteristics of the insulator surface when the surface is polluted,and it has a certain value to further improve the complex pollution flashover generation mechanism of the insulator,so as to better solve the pollution flashover problem of the insulator.The main research contents of this paper are as follows:In this paper,the 3-D finite element simulation model of the composite insulator string is established,the electric field and potential distribution of the insulator string under the condition of uneven pollution on the windward/leeward side are calculated,and the difference between the insulator cylinder and the shed of the leeward side drying zone is analyzed.The influence of position on the water droplet electric field on the windward side and the surface electric field and potential on the windward/leeward side,and the degree of distortion of the insulator creeping field strength and potential caused by the number of drying zones,and the distortion degree of the drying zone conductivity and the drying zone width to the insulator creeping field strength are also studied.For the condition of uneven pollution on the windward side and the leeward side of the insulator string,the simulation results show that when the leeward side is polluted with wet pollution,the maximum field strength on the leeward side appears at the outer edge of the fore and aft sheds,while the maximum field strength on the windward side is concentrate on the metal fittings at both ends of the insulator;the dry zone causes the water droplet electric field on the windward side to increase sharply to about 2MV/m,which distorts the field strength on the leeward side by 11 times;the field strength in the dry zone increases with the decrease in the conductivity of the dry zone.When it is less than 10^-5S/m,the electric field of the dry belt increases by 6.2MV/m and shows a saturation trend.In this paper,the PTFE plate is used to simulate the water band generation environment on the surface of the insulator,and the influence of the linear and broken line water band shapes on the flashover process of the hydrophobic surface is experimentally studied.Based on the finite element numerical calculation,the distribution of the water band and the surrounding electric field is analyzed.,and combined with the test results to discuss the mechanism of the water belt affecting the arc development path.The results show that when considering the weakening of the hydrophobicity of the composite insulator,the smaller the water band opening angleθ,the smaller the water band electric field,and the larger the dry band electric field between the water bands;at the same time,the smaller the water band spacing d,the smaller the dry band electric field.is also larger;therefore,when the hydrophobic surface has a zigzag water band,when the hydrophobic surface is attached with different forms of water band,the development of the arc will show three different types with the change of the included angleθof the water band and the lateral spacing d of the water band.