This paper investigates the impact of small uniform pressure rings on the surface electric field distribution of ultra-high voltage composite insulators for +800kV YunGuang ultra-high voltage direct current transmission lines under icing conditions. Firstly, the basic principles of the finite element method are introduced, and a +800kV composite insulator model is established. Considering that this paper uses double uniform pressure rings, when the composite insulator is completely iced, the ice edge may cover the small average on the high-voltage side. Therefore, it is necessary to study the effect of the ring diameter of the small uniform pressure ring on the surface electric field distribution characteristics of the insulator. The results show that when the ring diameter of the small uniform pressure ring is larger than that of the umbrella group, the voltage and electric field distribution characteristics of the insulator are relatively uniform.
Compared to glass and porcelain insulators, silicone rubber composite insulators offer advantages such as lighter weight, superior resistance to contamination, and minimal daily maintenance requirements, making them widely used in ultra-high voltage transmission lines. However, due to their differing structure and materials from porcelain insulators, the field intensity distribution along the composite insulator surface is more uneven.
Operational experience shows that high-field strengths occur at the junction of the high-voltage end shaft and the steel cap. When the surface field strength of the insulator and hardware exceeds the corona inception field strength, corona discharge occurs, thereby affecting the electromagnetic environment and insulating materials. Production factors, such as operating characteristics, are therefore crucial. Accurately understanding the electric field distribution of composite insulators, determining their high-field strength values and distribution patterns, and employing reasonable methods to improve the electric field distribution are important aspects of composite insulator research.
Among various methods to improve composite insulators and uneven electric field distributions, installing equalizing rings is a favorable approach. Some scholars suggest that adding double equalizing rings at both ends of DC composite insulators can enhance the electric field distribution on the surface of the composite insulator, by inserting a small equalizing ring between the metal fittings to control the electric field. The silicone rubber medium of the composite insulator.
Due to the inevitable passage of the +800kV cloud light ultra-high voltage DC transmission line through areas with icing and other special environments, when the composite insulator is completely iced over, the ice edge may cover the small equalizing ring of the high-voltage side equalizing ring. Therefore, it is necessary to study the influence of the ring diameter of the small equalizing ring on the surface electric field distribution characteristics of the insulator.
