Characteristics of icing without icicle on insulators under natural conditions

Icing on insulators seriously threatens the safe and stable operation of transmission lines. Most of the existing research has focused on the flashover characteristics of ice-covered insulators, lacking attention to the icing process on insulators. In order to reveal the mechanism of insulator icing, and lay the foundation for further establishment of insulator ice flashover model, this paper studies the characteristics of insulator icing without icicle. The characteristics of icing processes including the collision and freezing of water droplets, the generation and flowing of water film are analysed. On this basis, a three-dimensional numerical calculation model of insulator icing without icicle is established by using boundary element method, and the expressions of the local icing weight and thickness on the insulator surface are derived through the droplet local collision efficiency and freezing efficiency. Moreover, the time-varying characteristics of icing parameters are simulated. And the related icing tests are conducted on two kinds of insulators with different structures at Xuefeng Mountain. The results show that the distribution of collided water droplets and water film on the insulator surface will change with the increasing ice weight. Under natural conditions, compared with the aerodynamic insulator LDQ-100, the insulator LXY-120 with a smaller skirt diameter and a larger inclination angle can have a faster icing rate. However, at the insulator edge, the insulator LDQ-100 with a thinner shed has a greater icing rate of thickness. Compared with the test results, the simulation error of the model in this paper is within 15%.