热老化对XLPE电缆本体中典型缺陷所引发的电场畸变的影响  

Influence of Thermal Aging on Electric Field Distortion Caused by Typical Defects in XLPE Cable

作　　者：朱梦瑶 李欢 张瑞祥 ZHU Mengyao;LI Huan;ZHANG Ruixiang(School of Electrical Engineering,Shaanxi University of Technology,Hanzhong 723001,Shaanxi Province,China)

机构地区：[1]陕西理工大学电气工程学院,陕西省汉中市723001

出　　处：《中国电机工程学报》2024年第22期9076-9086,I0032,共12页PROCEEDINGS OF THE CHINESE SOCIETY FOR ELECTRICAL ENGINEERING

基　　金：陕西省教育厅一般专项项目(22JK0322)。

摘　　要：由缺陷所引发的局部电场畸变是电缆故障的重要诱因之一。现有的关于缺陷的仿真研究主要针对于未服役的电力电缆开展,缺少老化过程对缺陷所引发的电场畸变程度的影响研究。该文通过COMSOL有限元仿真软件研究热老化对电缆本体中外护套破损、受潮水珠、杂质颗粒、半导电层凸起和水树枝5种典型缺陷所引发的电场畸变的影响。结果表明,5种典型缺陷均会造成不同程度的电场畸变,其中水树枝所造成的电场畸变率最高,为456.2%;外护套破损缺陷引发的电场畸变率最低,为51.6%。随着热老化时间的增加,靠近外半导电层的缺陷所引发的电场畸变率逐渐升高,引发放电故障的风险提高;靠近内半导电层的缺陷所引发的电场畸变率逐渐降低,呈现出自愈的趋势;而位于绝缘中部的缺陷引发的电场畸变对热老化并不敏感。上述结果的产生源自于热老化交联聚乙烯(crosslinked polyethylene,XLPE)电缆绝缘的相对介电常数沿电缆径向的非线性分布。所构建的相对介电常数沿电缆径向的分布函数及推导该函数的方法有助于更为准确地研究交变电场下老化、服役电缆绝缘的电场分布特性。The local electric field distortion resulted from defects is one of the important causes of cable faults.The existing simulation research on defects mainly focuses on unused power cables,lacking research on the impact of aging process on the electric field distortion caused by defects.In this paper,the distribution function of the relative dielectric constant of crosslinked polyethylene(XLPE)insulation along the radial direction of the cable considering the thermal aging factor is constructed.The influences of thermal aging on the electric field distortion caused by five typical defects of outer sheath damage,moisture droplets,impurity particles,semi-conductive layer protrusion and water tree branches in the cable body are studied by COMSOL finite element simulation software.The simulation results show that all five typical defects can cause electric field distortion,with water tree branches causing the highest electric field distortion rate of 456.2%.The electric field distortion rate caused by the damage defect of the outer sheath is the lowest,at 51.6%.During the thermal aging process,the electric field distortion caused by defects near the outer semi-conduction layer gradually increases with the increase of aging time,leading to an increased risk of discharge faults,while near the inner semi-conduction layer,the distortion gradually diminishes,showing a self-healing trend.The electric field distortion caused by defects in the middle of the insulation is not sensitive to thermal aging.The above results are derived from the nonlinear distribution of the relative permittivity of the thermally aged XLPE cable insulation along the radial direction of the cable.The distribution function of relative permittivity along the radial direction of the cable and the method for deriving this function will help to more accurately study the electric field distribution characteristics of aging and in-service cable insulation under alternating electric fields.

关 键 词：交联聚乙烯电缆 热老化 典型缺陷 有限元仿真 电场畸变 

分 类 号：TM854[电气工程—高电压与绝缘技术]