检测电缆附件局部放电内置传感器的特性分析

Performance analysis of inner sensors used for partial discharge detection in cable accessories

针对高压交联聚乙烯(cross-linked polyethylen,XLPE)电缆的结构及其附件内部易出现绝缘缺陷而导致放电的特点,基于电容耦合原理研制出用于电缆附件局部放电(partialdischarge,PD)信号检测的宽频带电容型内置传感器,通过建立传感器特性分析的电路模型,全面分析了影响传感器性能的各个因素,对其响应的频率特性进行了实测,并在实验室110 kV XLPE电缆PD试验平台上对电缆接头内部沿固体复合介质表面产生的放电进行试验研究。测试结果表明:研制的内置电容型传感器频率响应特性优异,能传感纳秒级暂态脉冲信号,其有效频带达500 MHz,可以用于XLPE电缆及附件PD超高频(Ultra-high frequency,UHF)信号的检测。

The structure of high voltage cross linked polyethylene （XLPE） cable and the characteristics of partial discharge （PD） mean that such discharges are very likely to happen in cable accessories due to insulation defects. The authors designed a wideband inner capacitive coupler for PD detection in cable accessories, and analyzed the characteristics of the coupler using an equivalent circuit model. The frequency response characteristics of the coupler were measured by square wave response. In addition, the measured results of the surface discharge produced along the dielectric interface in joints are given in 110 kV XLPE cable accessories. It is shown that the couplers work well in bands up to 500 MHz and can detect nanosecond transient pulse signals effectively. The couplers are available for ultra-high frequency （UHF） measurement of PD in cables and cable accessories.