Research On Mechanism For Discharge Ablation Defect In Buffer Layer Of High-voltage XLPE Cable

When the buffer layer discharge ablation defects appear in the high-voltage XLPE cable,the ablation trace will appear at the defect position,and cable line breakdown accident will occur when it is serious.This will seriously affect the safe and stable operation of the power system.Therefore,it is of great significance in engineering value to study the mechanism of buffer layer discharge ablation defects,also it can reduce the cable line accident caused by such defects.Based on this background,the main research work of this paper is as follows:1.Analysis of buffer layer structure and defect characteristics.The main types of buffer layer used are investigated,and the structure and composition of semi-conductive polyester non-woven water blocking buffer layer are analyzed.The differences of buffer layer areas of different cable samples are analyzed.The defect characteristics are summarized according to the disassembly inspection phenomenon of defective cable.2.Study on the formation mechanism of white powder on the surface of buffer layer.According to characteristics and composition of water blocking powder,combined with the composition elements of white powder,the formation reason of white powder was analyzed.In order to verify the formation mechanism of white powder and analyze its influence on electrical performance,the simulation experiment of white powder formation was carried out.3.The equivalent circuit model of high-voltage XLPE cable with defects is established.According to insulation characteristics of white powder,the change of contact state between buffer layer and aluminum sheath is analyzed.Then the equivalent circuit model is established,and the equivalent circuit model corresponding to different defect degree is analyzed.4.Study on the mechanism and development process of the buffer layer discharge ablation defects.According to the equivalent circuit model,the simulation model is built.According to the simulation results,possibility of discharge phenomenon is analyzed.The characteristics and occurrence of discharge are verified by discharge simulation experiment platform.The defect mechanism is summarized and relevant suggestions are put forward.