电力电缆局放及温度的多维度检测方法研究

电力电缆在电力、建筑、通信等供电及辅助系统中应用愈来愈广,然而电力电缆在高电压、强电场、大电流以及复杂环境条件下,容易发生绝缘老化、电树枝化甚至击穿故障。此外由于铜损、介质损耗发热会导致电缆温度升高和恶化加剧,因此通过监测电缆局放及温度来实现监测电缆绝缘性,是保障电网安全运行的重要手段。本文研发了具有高速采集功能的高频检测模块(100MHz)。首先,基于此模块,本文结合同步信号降噪技术,滤除现场各种类型的干扰信号;结合聚类多源分离技术,解决了多源叠加影响类型诊断的问题;结合小波滤波降噪技术,有效的滤除窄带型干扰信号。此外,基于大量现场实践经验,构建了包含各种典型放电类型各个发展阶段的放电信息指纹库,实现了对局部放电缺陷类型的准确诊断和基于放电发展阶段的状态评估和预警。最后,提出了低成本高频局放及温度检测的改进方法,实现了局放及温度的同时监测功能,并提高了电力电缆局放及温度多维度检测的可靠性。

Research on multi-dimensional detection method of partial discharge and temperature of power cable

Power cable is more and more widely used in power supply and auxiliary systems, such as power, building, communication, etc. However, under the conditions of high voltage, strong electric field, large current and complex environment, power cable is prone to insulation aging, electrical treeing and even breakdown fault. In addition, the heating of copper loss and dielectric loss will lead to the increase and deterioration of cable temperature. Therefore, monitoring cable insulation by monitoring cable partial discharge and temperature is an important means to ensure the safe operation of power grid. In this paper, a high frequency detection module (100MHz) with high-speed acquisition function is developed. First of all, based on this module, combined with synchronous signal noise reduction technology, this paper filters out all kinds of interference signals on site; combined with clustering multi-source separation technology, it solves the problem of multi-source superposition impact type diagnosis; combined with wavelet filtering noise reduction technology, it effectively filters out narrow-band interference signals. In addition, based on a large number of on-site practical experience, a fingerprint database of discharge information including various typical discharge types in each development stage is constructed to realize the accurate diagnosis of PD defect types and the state evaluation and early warning based on the discharge development stage. Finally, an improved method of low-cost high-frequency PD and temperature detection is proposed, which realizes the simultaneous monitoring function of PD and temperature, and improves the reliability of PD and multi-dimensional temperature detection of power cable.