干式直流套管极板边缘电场分布及优化方法

As a critical part of the transformer and valve hall, resin impregnated paper (RIP) DC bushing has the largest electric field at the screen edge, from which the partial discharge is easy to start, causing insulation failure. How to effectively optimize the electric field at the screen edge has become one of the keys to improve the operating reliability of the RIP DC bushing. To further determine the distribution law and the optimization method of electric field at the screen edge of RIP bushing, the bushing core model with double capacitor layers was established, and the accuracy of traditional empirical formula under different parameters was analyzed. The optimization effects of having the screen edge half-folded, laying semi-conductive insulating paper or non-linear conductive material on the electric field at the screen edge were compared. The results show that the tradition theoretical formula has a small estimation of the maximum electric field at the screen edge, with its deviation about 7.5% and basically unchangeable with d/Δt. Also, the curvature radius of the screen edge can be doubled, and the maximum electric field can be reduced by 27.8% by using the screen edge half-folded method. When semi-conductive paper with its conductivity 10~100 times the RIP material is laid on the screen edge, the maximum electric field can be reduced by more than 31.4%, and the maximum electric field almost no longer decreases with the increase the conductivity of the semi-conductive paper. The method of attaching non-linear insulating material to the screen edge is promising, which can reduce the maximum electric field by 73.2%.