基于分布式无线TEV传感器的电缆终端局部放电监测系统

电力电缆是城市输配电系统的重要组成成分,其绝缘状态关系着城市供电的可靠性。局部放电检测是识别潜在绝缘故障的有效方法,可用于电力电缆的绝缘诊断。暂态对地电压法(TEV)是一种非电接触且应用较为灵活的局部放电带电检测手段,能够有效检测电缆终端或接头的局部放电。然而,由于电缆附件监测点分布较广,时效性要求较强且电磁环境差别较大,目前的TEV带电检测应用方法存在一定局限性。本文首先分析了电缆终端及接头处内部局部放电信号的时频特性,设计了能够有效耦合暂态对地电压的电容性TEV传感单元及信号预处理电路,并基于TEV物联网传感单元,建立了分布式TEV无线传感网络。本文对暂态对地信号的耦合原理、信号调理和采集、以及数据处理方法进行了研究,通过各传感节点放电量、趋势及模式识别,实现了关联故障预警。

Partial Discharge Monitoring System on Cable Terminal with Distributed Wireless TEV Sensors

Power cable is an important component of urban transmission and distribution systems, and its insulation status is related to the reliability of urban power supply. Partial discharge detection is an effective method to identify potential insulation faults and can be used for insulation diagnosis of power cables. Transient earth voltage (TEV) is a non-electrical contact and flexible application of partial discharge charging detection, which can effectively detect partial discharge of cable terminals or joints. However, due to the wide distribution of cable attachment monitoring points, strong timeliness requirements and large electromagnetic environment differences, the current TEV live detection application methods have certain limitations. In this paper, the time-frequency characteristics of the internal discharge signals at the cable terminations and joints are analyzed. The capacitive TEV sensing unit and signal pre-processing circuit capable of effectively coupling the transient-to-ground voltage are designed and based on the TEV wireless sensing unit. A distributed TEV wireless sensor network was established. In this paper, the coupling principle, signal conditioning and acquisition, and data processing methods of transient ground signal are studied. Through the sensing quantity, trend and pattern recognition of each sensor node, the associated fault early warning is realized.