DC flashover characteristics of iced post insulators in the natural environment

• Field study reports natural icing and DC flashover of porcelain post insulators. • Post insulator sheds are more easily bridged by ice ridges. • Flashover voltage fits a negative power-law with the pollution-ice parameter ISP. • The resistance of the insulator ice layer decreases with the increase of salt density. Icing can cause a significant drop in the electrical performance of insulators, leading to serious power grid disasters. In recent years, power grid disasters caused by icing on insulators have become common. However, the current research on the flashover characteristics of insulators under icing conditions at home and abroad mainly focuses on suspension insulators under artificial icing conditions, while there is little research on post insulators under natural icing environments. In addition, compared with suspension insulators, the sheds of post insulators are denser and have shorter spacing, making them more susceptible to ice bridging under the same icing conditions, leading to serious flashover accidents. Therefore, it is of great significance to study the DC ice flashover characteristics of post insulators. In this paper, natural icing growth observations and DC icing flashover characteristics of two types of porcelain post insulators, A and B, were carried out at Xuefeng Mountain Energy Equipment Safety National Observation and Research Station. The arc development process of the post insulators under different degrees of contamination and icing was analyzed, and the changes in ice layer resistance of porcelain post insulators and suspension insulators were calculated and compared. The research results of this paper can provide important reference value for the design and selection of external insulation of post insulators in substations and converter stations in ice-covered areas.