界面形态对XLPE-EPDM复合界面放电特性的影响研究

Effect of interface morophology on discharge chaeacteristics of XLPE-EPDM composite interface

电缆主绝缘与附件绝缘之间的界面击穿是电力电缆绝缘破坏的主要形式,为此有必要对固体复合界面击穿机理、放电特性进行研究。以XLPE-EPDM复合界面为研究对象,基于表面接触理论及界面放电试验,通过显微镜观测界面微观形貌并提取界面形态特征,研究了界面接触形态对复合界面放电特性的影响规律。结果表明,复合界面绝缘强度与界面形态特征之间有较好的关联性。随着表面粗糙度的减小,界面实际接触面积比例增大,接触点密度增大,气隙尺寸减小,界面形态改善;而局部放电起始电压、界面击穿电压均有所上升,放电重复率及放电功率均下降,局部放电强度降低。本研究为改进电缆附件材料与结构设计、选型、指导电缆附件安装工艺及电缆故障检测提供了理论基础。

The interface breakdown between cable main insulation and accessory insulation is the main form of power cable insulation damage,so it is necessary to study the solid composite interface breakdown mechanism and discharge characteristics.In this paper,the XLPE-EPDM composite interface is taken as the research object.Based on the surface contact theory and interface discharge test,the micro morphology of the interface is observed by microscope and the characteristic quantity of the interface morphology is extracted.The influence of the interface contact morphology on the interface discharge characteristics is studied.The results show that there is a good correlation between the insulation strength of the composite interface and the interface morphology.With the decrease of surface roughness,the ratio of actual contact area increases,the density of contact points increases,and the size of air gap decreases;however,the initial voltage of partial discharge and the breakdown voltage of interface increase,the repetition rate of discharge and the power of discharge decrease,and the intensity of partial discharge decreases.This study provides a theoretical basis for improving the material and structure design,type selection,guiding the installation process of cable accessories and cable fault detection.