Study On Contamination And Voltage Distribution Characteristics Of Insulator

With the improvement of the rated capacity and voltage levels for transmission line,together with the deterioration of the environment,the threat of insulator pollution flashover accident is becoming more and more larger for the safe operation of power grid.In order to effectively predict the pollution flashover accident occurred,the research for insulator disk contamination is more important.Insulators polluted by pollutant is the pre condition for pollution flashover.The distribution pattern of pollutant will affect the flashover voltage of single insulator,and the voltage distribution of insulator strings.The pollution of insulators is studied in this thesis.Analysis on molecular force shows that any surface has fouling performance.Therefore,the mechanical condition of the contaminated particles adhesion is obtained by mechanics analysis of contaminated particles contacting with the insulator surface.Pollution is usually diver by wind into the air,then adhere on the insulator surface.Accordingly,the fluid mechanics,point of view is applied and the pollutant particles near the insulator disk,is analyzed by the concept of laminar flow.The result shows that the wind would promote the accumulation of contamination on insulators and the deposition rate on the lower surface is significantly higher than the upper surface.The pollutant accumulation of the insulator disk is a dynamic process,which the pollutants will break away from the insulator surface caused by external force.The analysis on force of pollution particles shows that the wind force can't make the pollutant particles break away from the insulator,however,by the effect of wind and rain,a effective clearing of the insulator surface could be implemented and the pollutant an insulator surface presents a dynamic characteristics.In order to study the contamination distribution,the dynamic performance on the upper disk is simulated via artificial swearing.The contamination distribution could be divided into three types,which the voltage distributions of insulator strings are tested.Tests on three pieces of string and six pieces of string are conducted in the thesis.By the voltage distribution tests on various polluted insulators,we get the conclusions in the case of a centrally symmetric distribution the voltage distribution of insulator strings shows a downtrend from the cable,however,when the insulator string has non center symmetrical contamination,the voltage distribution will be distorted and random.After cleaning the upper surface of the insulator string,the voltage distribution appears regular pattern which decrease gradually from the cable.The pollution distribution on the upper surface of the insulator will impact the voltage distribution characteristics seriously,the voltage distribution will appear to be randomness caused by the block pollution.Cleaning is an effective may to make the voltage distribution downtrend which will make it easier to take measures to prevent pollution flashover.