卜字型电缆引下干式电缆终端头的力学与电学特性联合分析

Conjoint Analysis of Mechanical and Electrical Characteristics of Dry Cable Terminal in Bo-shaped Cable Down-lead Layout

卜字型电缆引下布置中由于干式电缆终端头弯曲形变导致电缆局放加剧、断裂等故障的情况已有报道,但目前尚未见电缆终端头弯曲形变程度与所受应力及电场强度的量化计算和关联性分析。鉴于此,根据卜字型电缆引下布置的结构特点,定义了弯曲角,并推导了量化计算弯曲形变和所受应力的数学模型;此外,沿终端头弯曲路径建立了电缆终端头内外部电场计算的数学模型,并以YJLW03-Z 64/110kV 1×400 mm^2型干式电缆终端头为例进行了仿真分析。研究结果表明：随着电缆弯曲角度的增大,终端头的最大形变量与终端内部所受应力均呈增大趋势,终端最大形变处各介质材料所受的最大应力增幅显著;电缆终端头内部电场强度与伞裙尖端电场强度呈增大趋势,且伞裙尖端电场强度增幅显著。通过力学和电学的联合分析,综合考虑电缆终端头各介质材料的抗拉强度和击穿场强,建议卜字型电缆引下干式电缆终端头的弯曲角不超过5°。

The partial discharge intensified and cracking caused by the bending deformation of dry cable terminal in Bo-shaped cable down-lead layout have been reported, but the quantitative calculation and correlation analysis of bending deformation, stress and electric-field intensity haven＇t been systematically studied. In this paper, according to the characteristics of Bo-shaped cable down-lead layout, the bending angle was defined and the mathematical models for calculating the bending deformation and stress of the cable terminal were derived. Furthermore, the mathematical model for calculating the electric-field both inside and outside the cable terminal was set up along its bended path. And the simulation analysis was carried out with the YJLW03-Z64/110 kV 1×400 mm～2 dry cable terminal. The research results show that, with the increase of the cable bending angle, the maximum shape is variable and the maximum internal stress of the cable terminal increases. The maximum stress of each dielectric material at the maximum deformation increases significantly. Besides, the electric fields inside the cable terminal and at the tip of the umbrella skirt also increase, especially, the increment at the tip of the umbrella skirt is remarkable. Through the conjoint analysis of mechanical and electrical characteristics, the limit value of bending angle of dry cable terminal in Bo-shaped cable down-lead layout is suggested as 5°.