整体预制式和绕包式XLPE高压直流电缆接头电场分布研究及接头结构优化

Research on the Electric Field Distribution and Structure Optimizing of Integral Prefabricated Joint and Taped Joint

整体预制式和绕包式接头是两种较为常见的电缆接头,由于它们的结构及绝缘的电导率各不同,接头中的电场分布存在较大差异。以50 kV交联聚乙烯高压直流电缆接头为研究对象,分别建立了整体预制式接头模型(增厚绝缘材料硅橡胶)和绕包式接头模型(增绕绝缘材料为油浸纸),应用有限元软件计算了温度梯度下两种接头中电场分布。研究发现对于整体预制式接头,当导体与环境温差达到40℃时,应力锥根部的电场强度可达到45 kV/mm,存在击穿危险;而对于绕包式接头,同样温差下,应力锥根部的电场强度几乎为0,但反应力锥顶部的电场强度达到30 kV/mm。通过对绕包式电缆接头的反应力锥顶部进行结构优化后,可使最大电场强度降低至7 kV/mm;通过采用聚四氟乙烯绕包的方式可使反应力锥顶部最大电场强度降低至3 k V/mm。以上研究可供高压直流电缆接头设计时参考。

Integral prefabricated joint and taped joint are two kinds of widely used cable joint.Because of the different structure and conductivity of insulation,there is great difference in the electric field distribution between the two kinds of joints.In this paper,50kV crosslinked polyethylene high voltage dc cable joint is selected as the research object,models of Integral Prefabricated Joint(silicone rubber insulated)and taped joint(oil impregnated paper insulated)was established and the electric field distribution in the joints was analyzed by comsol software.It is found that the electric field at the root of stress cone reached45kV/mm for Integral Prefabricated Joint.The electric field at the root of stress cone was nearly0kV/mm for taped joint but the electric field at the top of reversed stress cone reached30kV/mm.By optimizing the structure of the taped joint,the maximum electric field is reduced to7kV/mm.By using Teflon as the taped insulation which can reduce the maximum electric field to3kV/mm.The research is a reference in the HVDC cable joints design.