500 kV SF6 电流互感器内部盆式绝缘子缺陷电场分析和实验研究

近年来,涉及SF₆气体绝缘电流互感器故障次数较以往明显增多。为此,对一起故障的500 kV SF₆电流互感器进行解体事故分析,发现事故是由运行过程中内部盆式绝缘子产生缺陷造成的。为深入了解气体绝缘电流互感器绝缘特性,从源头上防止突发性故障,依据SF₆气体绝缘电流互感器事故分析结果,对盆式绝缘子有气泡、裂缝、金属污染等缺陷的情况进行了三维电场仿真计算分析和局放实验研究。研究结果显示：有缺陷的盆式绝缘子电场发生畸变,尤其是有金属污染时电场畸变最为严重,局放电压急剧下降。研究得出的数据和结论为SF₆气体绝缘电流互感器的绝缘设计、结构优化、运行维护和故障分析提供了理论参考依据。

Electric Field Analysis and Experimental Study of Defective Basin Insulators Within SF6- Gas-Insulated Current Transformers of 500 kV

The number of faults of SF₆-gas-insulated current transformer notably increases in recent years. By analyzing an accident of a 500 kV SF₆ current transformer, it is shown that the cause is the internal defects of the basin insulators in the current transformer during operating. In order to investigate the insulation characteristics of gas-insulated current transformers and find the root causes for the sudden faults, three dimensional electric-field simulations and partial discharge tests based on the accident analysis of SF₆-gas-insulated current transformer with the insulators those have the defects of air bubbles, cracks and sheet metal were carried out. The results illustrate that the electric field of the defective basin insulator is distorted. Especially, in case of metal pollution, the electric field is seriously distorted and partial discharge voltage drops sharply. The investigation data and conclusions provide a theoretical reference for the insulation design, structural optimization, operation maintenance and fault analysis of SF₆-gas-insulated current transformers.