配电电缆中受潮接头的阻抗特性及其检测方法研究

Study on impedance characteristics of moisture ingress in cable joint and its detection method

电缆接头是电力电缆中最脆弱的部位,接头受潮是中压交联电缆的常见缺陷,如果未能及时得到修复,将导致电缆过早失效。文章围绕中间接头受潮后的阻抗特性及其检测方法开展研究,阐述了波在电缆中传播的折反射现象,以时域反射法的理论知识为基础,在CST(computer simulation technology)Studio Suite中建立了10 kV冷缩式中间接头的三维单芯模型,对中间接头不同程度进水情况下的阻抗特性和反射波形进行研究;在实验室10 kV交联聚乙烯电缆中间部位的电缆接头上制作进水缺陷,分别进行电缆接头S参数测量和时域脉冲反射实验。最后,分析和比较了电缆受潮接头的阻抗特性仿真和实验结果,证明了使用时域脉冲反射技术对受潮电缆中间接头进行受潮诊断的可行性和有效性。

Cable joint is one of the most vulnerable parts of power cables.Moisture ingress with joints is a common defect of medium-voltage cross-linked cables.If not repaired timely,it will develop into premature failure of cable.This paper studies the impedance characteristics after moisture ingress into cable joints and their detection method.The principle of refraction and reflection of wave propagation on power cable is briefly formulated.Based on the theoretical knowledge of time domain reflectometry(TDR),the three-dimensional model of single-core 10kV cold-shrinkable cable joint is established in the computer simulation technology(CST)Studio Suite to investigate the impedance characteristics and reflected waveforms of the joint under different moisture degrees.The moisture defects are made on the joint of the middle part of the 10 kV XLPE cable in the laboratory,and the S parameter measurement of joint and time-domain pulse reflectometry experiment are carried out respectively.The simulation and experimental results of impedance characteristics of moisture ingress on cable joint are analyzed and compared,which validates the feasibility and effectiveness of using TDR to diagnose defected joints due to moisture ingress.