局部放电信号在XLPE电缆中间接头中传播特性的研究

Simulation Analysis on the Propagation Characteristics of PD in XLPE Cable Joints

为提高电力电缆系统中局部放电(PD)测量和定位的准确性,考虑到半导电层和多层复合介质的频变特性,基于传输线理论和有限积分法(FIT)建立10 k V交联聚乙烯(XLPE)电缆中间接头的数学物理模型,仿真分析了局部放电信号在XLPE电缆中间接头中的传播特性。仿真结果表明:中间接头内部特征参数随结构和电磁波频率变化而变化,PD信号经过中间接头后,高频信号较低频信号衰减快,入射波衰减和畸变都较相同长度本体中严重,且反射波信号幅值较大,接头内部能量衰减主要集中在连接头附近。波阻抗在接头过渡段和连接头段变化较大,将对局放脉冲折、反射起主要作用;PD信号在中间接头中平均传播速度与电缆本体中基本相同。

To improve the measurement and location accuracy of partial discharge （PD） in XLPE power cable sys- tems, it is necessary to analyze the propagation characteristics of PD in XLPE cable joints. In this paper, the model of 10 kV XLPE cable joint was established based on the transmission line theory and Finite Integration Technique （FIT）, taking into account the frequency-dependent properties of semi-conductive layer and multi-layer composite media. The simulation results indicate that the characteristic parameters of cable joint changes for different structures and frequency, high-frequency signal decays faster than low-frequency signal and energy attenuation is mainly concen- trated near the connector. Moreover, wave impedance in cable joint changes obviously in the transition section and connector segment, playing a major role in the reflection of electromagnetic wave. The average velocity of electromag- netic wave propagate in the joint is substantially the same with the cable.