Study on Pollution Classification and External Insulation Configuration of 1000kV Sichuan-Chongqing UHV AC Transmission Line

The insulators in operation are exposed to the air. Under the conditions of humid air (such as fog and drizzle), when they are seriously polluted, and the external insulation configuration is insufficient, the insulators will have pollution flashover, leading to a power failure of the line. UHV transmission lines feature large energy transmission and long distance. Once pollution flashover accident occurs, it will seriously threaten the stability of the power supply system
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. Therefore, it is of great significance to determine the design of external insulation configuration of ultra high voltage project scientifically and economically. In this paper, the climatic environment, pollution source distribution and operating experience of nearby projects along the Sichuan-Chongqing transmission line are studied and analyzed. The AC pollution level is proposed. Through the research and analysis of insulator pollution test data of transmission lines along the Sichuan-Chongqing line, the key pollution accumulation characteristics of insulators in different environmental areas along the project, namely, the pollution ratio of top and bottom surface areas, are determined. The pollution flashover tests under different pollution conditions of top and bottom surface areas were carried out, and related pollution coefficients were obtained. According to the results of artificial pollution flashover voltage test of insulators, combined with the equivalent salt deposit density characteristics in Sichuan and Chongqing, the external insulation configuration under typical pollution conditions along the Sichuan-Chongqing UHV line was recommended.