Study On Natural Contamination Characteristics And Its Influence Factors Of Post Insulators

Pollution flashover accident has more and more serious harm on power system,surface pollution accumulation of external insulation in the operation of power transmission and transformation equipment would affect its pollution flashover performance,therefore many studies on pollution accumulation of external insulation have been carried out at home and abroad.It is widely believed that regular cleaning of pollution on substation equipment could avoid pollution flashover accident,so the research institutions mainly focus on pollution accumulation of suspension insulators,then contamination characteristics and laws of post insulator in substation are not comprehensive.In the thesis,the study on natural contamination characteristics of post insulators has been carried out which is of great practical significance to figure out natural contamination characteristics and influence law of post insulators and to scientifically guide the anti-contamination work in substation.In this paper,by taking the working post insulators in substations as the research object,the suitable pollution collection method and measurement process were determined,pollution on post insulators of 35 kV,110kV and 500 kV in eleven substations was measured,and natural contamination characteristics and its Influence factors were analyzed according to the test results;then a CFD simulation model of post insulator was founded to analyze the influence of post insulator type,air flow and pollution particle parameter on pollution accumulation;finally,the simulation of electric field distribution on the surface of post insulator under different pollution conditions was carried out to further explain natural contamination characteristics of post insulators.The main achievements obtained from the above research are:(1)The results of natural contamination test show that,there is a difference in the pollution accumulation between high voltage terminal,middle position and earth terminal of post insulator shed at charge;the pollution accumulation on top surface is generally worse than that on down surface of post insulators in natural contamination test;the pollution accumulation on post insulator is affected by the surrounding environment and structure type in different substations.(2)The results of fluid mechanical emulation show that,surface pollution particle volume fractions of post insulator is affected by structure type,angel of air flow,wind velocity,pollution concentration and pollution particle diameters to further explain and verify the law obtained from natural contamination test.(3)The results of electric field distribution simulation show the interaction between the distribution of pollution and electric field on the surface of post insulator,which means that the pollution distribution is affected by non-uniform electric field distribution on the surface of post insulator,and the non-uniform pollution distribution has further aggravated the distortion of electric field distribution of post insulator.