极性反转下低密度聚乙烯空间电荷动态特性的数值模拟  

Numerical Simulations of Dynamic Space Charge Characteristics in Low Density Polyethylene Under Polarity Reversal

作　　者：郑跃胜[1] 钟小燕[1] 缪希仁[1] 何金良[2] ZHENG Yuesheng;ZHONG Xiaoyan;MIAO Xiren;HE Jinliang(College of Electrical Engineering and Automation,Fuzhou University,Fuzhou 350108,China;Department of Electrical Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]福州大学电气工程与自动化学院,福州350108 [2]清华大学电机工程与应用电子技术系,北京100084

出　　处：《高电压技术》2017年第2期385-390,共6页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2014CB239500)~~

摘　　要：直流电缆在运行时如果电压极性发生反转,会使得外加电场与累积空间电荷所产生的电场叠加而增强,可能引起局部放电或介质击穿。目前的实验测量方法无法揭示极性反转过程中空间电荷和电场的瞬态变化,尤其是微观粒子之间的相互作用过程。为了深入研究高压直流电缆在极性反转下的内绝缘机理,利用双极电荷传输模型对低密度聚乙烯(LDPE)的空间电荷动态特性进行了数值模拟,并通过仿真研究了多次极性反转下LDPE空间电荷和电场的瞬态分布。结果表明:极性反转时表面电场大大增强,并具有一定的极性效应,在由阳极转变为阴极时更加显著;极性反转前陷阱电荷密度远大于自由电荷密度,极性反转时电极表面电场的增强主要是由电极附近的陷阱电荷所决定。研究成果可为高压直流电缆的绝缘设计提供参考,也可以为聚合物材料空间电荷的动态仿真提供借鉴。The field intensity will be strengthened with the electric field induced by space charges added on the applied electric field if the voltage polarity of DC cable is reversed, which is possible to cause partial discharge or dielectric breakdown. The transient variations of space charges and electric field during the process of polarity reversal is difficult to be revealed by the present measurement methods, especially the interaction processes between microscopic particles. In order to deeply study the effects of the polarity reversal on the insulating properties of HVDC cables, the dynamic characteristics of space charges in low density polyethylene （LDPE） are numerically investigated by the bipolar charge transport model. Meanwhile, the transient distributions of space charge and electric field in LDPE under several polarity reversals are investigated. The results show that the surface electric field is strongly strengthened under polarity reversal. The field variation is of the polarity effect, which is more significant under the anode transiting to the cathode. The density of trapped charges is much higher than that of mobile charges before polarity reversal. And the strengthened electric fields on the electrode surfaces under polarity reversal are dominated by the trapped charges in the vicinity of the elec- trodes. The results can provide a reference for the insulation design of high voltage DC cables, as well as the dynamic simulation of space charges in polymeric materials.

关 键 词：低密度聚乙烯 直流电缆 空间电荷 极性反转 电场 有限元分析 

分 类 号：TM215.1[一般工业技术—材料科学与工程]