Contamination Characteristics And Electric Field Distribution Of High Voltage Insulators

In recent years,with the increasing of the voltage level of overhead transmission lines in China,the pollution flashover accident of insulator sometimes occurred.The flashover of insulators is closely related to contamination and distribution of electric field and potential along insulator surface.At present,the domestic and foreign scholars mainly study the distribution of potential and electric field along insulator under uniform contamination conditions or in the presence of dry band condition.However,research on the contamination deposited characteristics of insulators with direct current voltage(DC voltage),and the electric field distribution characteristics of insulators under the uneven pollution conditions is still less.In this work,an electrostatic model is developed and coupled with a two-fluid computational fluid dynamic(CFD)model to simulate contamination process of insulators.The description of the electrostatic model is presented.Then,the numerical implementation and verification of the electrostatic model with simple test cases are described.The numerical simulation of the pollution process of the XP13-160 insulator(Suzhou electric porcelain factory)was conducted.The contamination characteristics and the distribution of pollution layer of insulators’ surface are studied.The influence of particle charge,operation voltage level and wind speed on the pollution distribution of the insulator is discussed.The validity and accuracy of the simulation model is verified by the results of a wind tunnel contamination test.According to the distribution of contamination layer(spatial distribution and thickness distribution),a finite element analysis model is established,to calculate the electric field of polluted insulator.The electric field distribution characteristics of single insulator and insulator string under an uneven pollution condition and 4 typical kinds pollution distribution were studied.The influence of pollution conductivity on the electric field distribution was analyzed.Finally,an experiment was conducted to analyze distribution characteristics of natural pollutants on insulator in Suzhou area.This study shows that contamination on insulator with DC voltage is more serious than insulator without DC voltage.When particles are positively charged,the contamination on windward and leeward decreases with the increase of particles’ charge-to-mass ratio,and contamination on the lower surface of insulator increases with the increase of particles’charge-to-mass ratio,while the situation is opposite when particles are negatively charged.The contamination on windward and leeward increases with the increase of wind speed,but the growth rate of leeward is higher than windward when insulator without DC voltage.When wind speed is small and insulators have DC voltage,contamination on windward is larger than leeward.Contamination on the lower surface shows a tendency to decrease first and then gradually increase with the increase of wind speed.The difference of contamination on insulator with DC voltage or without DC voltage decreases with the increase of wind speed.The electric field distribution of polluted insulator is resistive-capacitive.For fully polluted conditions,an increase in pollution conductivity expands the linearity of the potential distribution.While potential distributions for partially polluted conditions are nonlinear.For uneven polluted condition,the electric field distribution characteristics of insulator strings at different creepage distances along the surface are different.The potential of windward side is lower than the leeward side,and potential change on the leeward side is relatively gentle.The average electric field strength of windward side,leeward side and crosswind side is larger than the average electric field strength under cleaning condition with the increase in pollution conductivity,and the electric field intensity distortion of leeward side is largest.In the natural pollution test,the particle size of 90%polluted particles on insulator is less than 1 μm,the average particle size is 3.4μm,and the maximum particle size is 41 μm.