直流XLPE电缆用预制接头最大场强解析算法

An Analytical Solution for Maximum Field Strength at the Pre-fabricated Joints of DC XLPE Cables

由于电缆接头结构复杂并含有多个复合界面,对其进行直流电场分析通常需要借助数值仿真软件、采用电-热耦合方法进行迭代计算,耗时费力。为了满足工程中仅对中低压直流XLPE电缆用中间接头最大场强进行校核的需求,利用传热学与电磁学相关理论,建立接头热场分布的简化分析模型,推导出计算应力锥根部场强的解析式,仅需输入少量必要参数,即可确定接头中的最大场强。通过以10 kV和35 kV XLPE电缆用硅橡胶和乙丙橡胶接头为例,分别在不同直流电压及接头内外温差下进行解析计算,并与相应的有限元仿真结果对比,验证所提方法的计算精度及适用性,为工程人员进行中低压直流预制接头的设计及校核提供强有力工具。

Due to the complex structure and multiple composite interfaces of the cable joints,the DC electric field distribution is usually analyzed by means of a numerical simulation software,which uses the electric-thermal coupling method for iterative calculation,and is time-consuming.In order to evaluate the maximum field strength at the joint for medium and low voltage DC XLPE cables,a simplified analytical solution was presented.Based on the theories of heat transfer and electromagnetics,a simplified model was established for analyzing the thermal field distribution at the cable joint,and an analytical formula was derived for calculating the field strength at the foot of the stress cone,with which only a few necessary parameters are needed to determine the maximum field strength at the joint.In this paper,by taking the prefabricated joints of silicone rubber and ethylene-propylene rubber for the 10 kV and 35 kV XLPE cables as an example,analytical calculations were carried out under different DC voltages and temperature differences between the joint inside and outside,and the analytical results were compared with those from the finite element simulation.The consistence between them verifies the accuracy of the proposed analytical solution and its applicability for the design and evaluation of the medium and low voltage DC cable pre-fabricated joints in practical projects.