Ice accretion on the insulator changes its electric field distribution, which seriously endangers security and stability of power grid. It is of great significance to study the electric field of iced insulator for disaster prevention and mitigation of power system. At present, the two-dimensional axisymmetric model of ice-accreted insulator is established to study the electric field. However, the effects of uneven icing, number of icicles, inclination angle of icicle, ice pallets and arc ignition on the electric field are ignored, which is inconsistent with the actual circumstance. Considering this, a three-dimensional simulation model of ice-covered insulator with applied voltage was developed in the present study. The average electric field intensity of air gap (E_av) and maximum field strength of icicle tip (E_max) were determined to characterize the influence of various factors on the electric field distortion degree. The results show that compared with the insulator without ice and with a dry ice, the supply voltage is almost entirely applied to all icicle air gaps for a wet ice-covered insulator. E_av is independent of icicle diameter and icicle number but increases with the increment of icicle length and icicle inclination angle. E_max raises with the increase of icicle length, icicle number, icicle inclination angle and icicle diameter. As the source of electric field distortion, ice pallets on the surface of the sheds rise the field strength of air gap. Based on the simulation analysis, the applied voltage is redistributed in the remining air gaps when an arc occurs in the gap near the high-voltage terminal, thereby causing the subsequent flashover.

ice-covered insulator,3D electric field,simulation calculation,arc,flashover