Research on snow removal of energized UHV DC wall bushing

Abstract

When the surface area of the wall bushing in the UHV DC converter station is polluted, there is a risk of wet snow flashover in the snow climate. The snow removal in time of the wall bushing can reduce the risk of outdoor insulation. For the horizontal insulator, we designed snow removal tests under the influence of various factors. The effect of various snow removal factors on the discharge characteristics were studied on the short insulator (4 m), while the UHV full-size wall bushing insulator (10.87 m) was studied by withstand test. The energized snow removal test results showed that under the same snow removal ratio, a position with a lower electric field value along the string should be selected as the starting snow removal position. Simultaneous snow removal on multiple sections was easier to cause surface discharge than the continuous long gap snow removal. The ratio and the degree of discharge appear to decrease first and then increase in a “spoon” shape. It was recommended to remove snow from the middle of the bushing firstly, and the first snow removal ratio in a continuous area was from 13% to 20% of the insulation distance. The research results of this paper can effectively guide the energized snow removal operation of ±800 kV DC wall bushings, and provide a reference for the energized snow removal operation of outdoor horizontal insulation equipment of other voltage levels.