基于泄漏电流频谱特征的XLPE电缆电树缺陷诊断技术

Electrical Tree Defect Diagnosis Technology for XLPE Cable Based on Spectrum Characteristics of Leakage Current

实现电缆电树缺陷的在线诊断对电力系统的稳定运行具有重要意义。泄漏电流蕴含丰富的绝缘信息且满足现场带电检测的需求,是极具前景的可实现在线监测与诊断的检测手段。开展基于泄漏电流频谱特征的XLPE电缆电树缺陷诊断技术研究,从实验研究与仿真分析两方面开展相关工作。首先搭建XLPE电树培养与泄漏电流检测平台,在电树缺陷从起始到击穿的全过程中,对电树枝的形态以及泄漏电流幅值与频谱特征进行实验研究;然后建立电树缺陷物理场仿真模型,计算不同形态下电场强度分布,并分析电场特征与泄漏电流频谱特征的相关性。研究结果表明,在电树缺陷击穿前15 min左右,泄漏电流的幅值在短时间内由585.3μA逐步增大至1 200μA以上,总谐波畸变率短时间内由7.7%增长至35%以上,以泄漏电流的幅值和总谐波畸变率为特征参量,可以在击穿前对电树缺陷进行诊断预警。相关性分析结果表明总谐波畸变率与电场强度正相关,其有着作为电缆缺陷类型诊断参数的潜力。

The online diagnosis of cable electrical tree defects is of great significance for the stable operation of the power system.Leakage current contains rich insulation information and meets the needs of the online detection,making it a highly promising detection method that can achieve online monitoring and diagnosis.This paper conducts research on XLPE cable electrical tree defect diagnosis technology based on leakage current spectrum characteristics,and carries out related work from both experimental research and simulation analysis.Firstly,an XLPE electrical tree cultivation and leakage current detection platform was established to conduct experimental research on the morphology of the electrical tree,as well as the amplitude and spectral characteristics of leakage current,throughout the entire process of electrical tree defects from initiation to breakdown.Then,a physical field simulation model for electrical tree defects was established to calculate the distribution of electric fields under different forms,and the correlation between electric field characteristics and leakage current spectrum characteristics was analyzed.The research results indicate that around 15 minutes before the breakdown,the amplitude of the leakage current changes from 585.3μA in a short period to above 1200 mA,THD increases from 7.7%to over 35%.Using the amplitude of leakage current and THD as characteristic parameters,it is possible to diagnose and warn of electrical tree defects before breakdown.The correlation analysis results indicate that THD is positively correlated with electric field strength,and THD has the potential as a diagnostic parameter for cable defect types.