特高压GIL电接触结构选型及磨损特性研究

Comparison Between UHV GIL Electrical Contact Structure Schemes and Analysis of Their Wearing Characteristics

在特高压气体绝缘金属封闭输电线路(gasinsulated line,GIL)综合管廊工程中,GIL敷设距离长,加之环境温度变化和电力系统调峰容易引发载流导体的热胀冷缩,通常采用电连接结构来实现位移补偿和电力连接。为探究特高压GIL电连接结构的选型优劣性,围绕特高压GIL电连接结构的2种方案,搭建了滑动触头劣化摩擦特性试验平台,获得磨损特性与接触特性。研究发现,弹簧触指和表带触指2种方案的接触电阻随摩擦次数的增加呈现先下降后上升的趋势,弹簧触指从1μΩ上升至4μΩ,而表带触指主要在1~1.5μΩ波动,磨损碎屑的等效直径主要分布在100~800nm之间,碎屑量的增加是接触电阻升高的重要原因。对比2种方案,弹簧触指分层磨损严重,而表带触指接触电阻较低,磨损量少,接触性能优于弹簧触指,更适用于GIL插接结构的配置。同时,研究发现含氟润滑脂的引入会引起CuF等金属氟化物的形成,对电连接结构造成不利影响,应考虑选用不含氟润滑脂来减少机械磨损。研究结论可为GIL插接结构的触指选型、劣化分析机理、润滑脂选型提供理论指导依据。

The ultra-high voltage(UHV) gas insulated line(GIL) corridor project usually has a long laying distance coupled with ambient temperature changes and power system peaking, easily causing the thermal expansion and contraction of the current-carrying conductors. The electrical connection structure is used to realize the displacement compensation and the electrical connection. In order to investigate the advantages and disadvantages of the UHV GIL electrical connection structure, this paper builds a sliding contact deterioration friction characteristic test platform around the two schemes of the UHV GIL electrical connection structure. The wearing and contact characteristics of the structure are obtained. It is found that the contact resistances of the two schemes of spring contact and strap contact show a decreasing first and then increasing trend with the increase of the friction times. The spring contacts increase from 1 μΩ to 4 μΩ, while the strap contacts mainly fluctuate from 1 μΩ to 1.5 μΩ. The equivalent diameters of the wearing debris are mainly distributed between 100nm and 800nm, and the increase in debris is an important reason for the increase of the contact resistances. Comparing the two schemes, the spring contacts has a severe delamination wearing, while the strap contacts has a better contact performance than the spring contacts with lower contact resistances and less wearing, which is more suitable for the configuration of the GIL plug structure. Meanwhile, it is found that the introduction of fluorine-containing grease may cause metal fluoride such as CuF, adversely affecting the electrical connection structure. It should be considered to reduce mechanical wearing with non-fluorinated grease. The study will provide theoretical guidance for the GIL plug structure, the deterioration analysis mechanism, and the grease selection.