基于电-热场联合分析的EPR中压电缆终端异常热点仿真分析及优化

25 kV乙丙橡胶(EPR)中压电缆终端因其自身的结构特性,内部电-热场分布不均,局部易出现异常畸变热点问题,而在安装电缆终端时出现的划伤缺陷加大了问题的严重程度,加速缺陷周围绝缘材料的老化,大幅降低了绝缘性能。为解决该问题,提出了一种电导率与电场、温度相关的非线性应力管材料,采用COMSOL仿真方法对比研究了使用高介质材料与非线性材料制作应力管时电缆终端内部的电-热场分布。结果表明,经优化后电缆终端的电-热场分布畸变程度能得到有效缓解;对于存在划伤缺陷的情况,优化后的电缆终端的电-热场畸变程度低于其出现击穿现象的阈值,表明其能够在缺陷情况下相对安全运行。同时采用热成像仪现场测试电缆终端温度分布,结果验证了经优化后电缆终端表面异常发热情况的改善效果。

Simulation analysis and optimization based on electric-thermal field for abnormal distortion hot spots of EPR medium voltage cable terminal

Due to the structural characteristics of the 25 kV EPR(Ethylene-Propylene Rubber) medium voltage cable terminal, the distribution of electric-thermal field inside the cable terminal is uneven, and the cable terminal partially has abnormal distortion hot spots. The scratch defects in the installation process of cable terminal increase the severity of the problem, accelerate the aging of the insulating material around the scratch defects, and greatly reduce the insulation performance. In order to solve the above-mentioned problems, a nonlinear stress tube material with conductivity associated with electric field and temperature is proposed. The COMSOL simulation method is used to compare the internal electric-thermal field distribution of the cable terminal with control tubes using high dielectric material and nonlinear materials. The results show that the electric-thermal field distortion of the cable terminal can be effectively alleviated after optimization. In the case of scratch defect, the electric-thermal field distortion of the optimized cable terminal does not reach the breakdown threshold, indicating that its operation is relatively safe. The temperature distribution of cable terminal in field is tested by the thermal imager, and the results show that the abnormal heating of the cable terminal surface is relieved after optimization.