双层绝缘结构高压直流电缆电场分布仿真  

Simulation on Electric Field Distribution in HVDC Cable with Double-layered Insulation

作　　者：李忠华[1] 陈漳 

机构地区：[1]哈尔滨理工大学工程电介质及其应用技术教育部重点实验室,哈尔滨150080

出　　处：《高电压技术》2017年第11期3504-3513,共10页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2014CB239504)~~

摘　　要：参照油纸绝缘高压交流(HVAC)电缆的分阶绝缘设计思想,采用不同非线性绝缘材料制造具有双层绝缘结构的高压直流(HVDC)电缆来改善电场分布以及减薄绝缘层厚度是一种可能的解决途径。为了从理论上验证双层绝缘设计理念在HVDC电缆绝缘设计中的可行性,采用多物理场耦合软件仿真研究了不同温度梯度、不同施压方式下分层半径对双层绝缘结构HVDC电缆绝缘稳态和暂态电场分布的影响规律,在此基础上定义了同时考虑稳态、暂态电场和温度梯度多重因素的综合绝缘利用系数,并提出了按绝缘材料的电导率内小外大排列、相对介电常数内大外小排列确定内外层绝缘原则和综合绝缘利用系数最高的分层半径确定原则,最后验证了该双层绝缘设计原则的合理性。电场仿真结果发现:与单层绝缘电缆相比较,双层绝缘结构HVDC电缆在高温度梯度下可显著改善电缆绝缘稳态和暂态电场分布,且温度梯度越高改善效果越显著;雷电冲击过程中绝缘内的暂态电场分布受直流稳态过程形成的界面及空间电荷的影响,而双层绝缘结构HVDC电缆绝缘稳态过程中形成的界面及空间电荷与温度密切相关,因而温度也是影响雷电冲击过程中绝缘暂态电场分布的因素。According to the design idea of oil-paper high-voltage alternating current （HVAC） cable with graded insulation, high-voltage direct-current （HVDC） cable with double-layered insulation is manufactured by different nonlinear dielectric materials, and this is a possible solution to improve the electric field distribution and reduce the thickness of insulation. In order to verify the feasibility of double-layered insulation design concept of HVDC cable in theory, we analyze the effects of layered radius on the steady and ransient electric field distribution in HVDC cable with double-layered insulation by using the software of COMSOL Multiphysics under different temperature gradients and voltage types. By the simulation analyses, we define a synthetical insulation utilization coefficient considering multiple factors of the steady and transient electric field and temperature gradient. The design principle for double-layered insulation is that the dielectrics with lower conductivity and higher permittivity are used for inner layer insulation, and the layered radius is designed with the maxi- mum of synthetical insulation utilization coefficient. Finally, the rationality of the double-layered insulation design principle is verified. The simulation results show that HVDC cable in the presence of double-layered insulation can sig- nificantly improve the electric field distribution under high temperature gradient, compared with single-layered insulation cable. The higher temperature gradients become, the more significantly the effect improves. Transient electric field distri- bution under insulation layers in the process of the lightning impulse is mainly affected by the interface charge and space charge formed in DC steady state, and the interface charge and space charge formed in steady state are closely related to temperature in HVDC cable with double-layered insulation, thus the temperature is also one of impact factors of transient electric field distribution under insulation layers in the process of the lightn

关 键 词：HVDC电缆 双层绝缘结构 绝缘利用系数 暂态电场 温度梯度 

分 类 号：TM247[一般工业技术—材料科学与工程]