35kV电缆终端局部放电智能检测技术研究

发布时间：2019-05-23 13:19

【摘要】：随着中国电力事业的不断发展,投入使用的XLPE电缆及其附件也与日俱增。目前,投入使用的电缆及其终端随着运行时间的增加,发生局部放电的可能性也在增大。自上世纪七十年代开始,已经研究出各种局放检测设备来研究局放发生的位置、局部放电量大小、老化程度等。在综合考虑局部放电、水树枝、电树枝老化特征的情况下,本文构建了一种基于高频脉冲电流法的35kV电缆及其终端局部放电检测智能诊断系统。 本文对电缆及其终端局部放电和水树、电树发生的原理、检测方法及相关实验结论做了系统分析。根据35kV电缆终端可能出现局放的位置,利用有限元法对不同大小和形状的局放缺陷模型进行1：1建模仿真,以便研究电缆终端内部场强分布、电势分布等特征,并进一步了解电缆终端内部局放发生机理,并对其老化诊断提供理论参考。仿真分析得出：电缆终端铜屏蔽层断口处是发生局放的薄弱环节,具有较高的局部场强；在可能产生局部放电的各处位置,割伤缺陷较凹陷缺陷有更大的场强,更容易发生局部放电。电缆终端缺陷模型形状越尖锐,电场畸变越严重,场强越大。铜屏蔽层断口附近存在气隙等缺陷时,局部场强大于空气击穿场强30kV/mm,极易产生局放,且越靠近断口处场强越大。 本文将粗糙集和神经网络相结合的故障诊断方法应用于电缆终端的局放类型模式识别和老化诊断分析。以此方法为根据,配合虚拟仪器技术和高频脉冲电流传感器及专业局放数据采集设备构建了35kV电缆及其终端局部放电检测智能诊断系统。所构建的系统可实现对实时数据进行频谱分析,查看历史数据,粗糙集—神经网络智能诊断以及用户信息管理等工作。 本文通过采用粗糙集—神经网络联合诊断方法与只依靠BP神经网络的诊断算法对比得出：粗糙集—神经网络相结合的诊断方法具有更好的局放类型识别率和容错性,且训练时间低于BP神经网络方法。
[Abstract]:With the continuous development of China's electric power industry, the XLPE cable and its accessories are also increasing day by day. At present, with the increase of running time, the possibility of partial discharge is also increasing. Since the 1970s, a variety of partial discharge detection equipment has been developed to study the location, local discharge capacity, aging degree and so on. Considering the aging characteristics of partial discharge, water branch and electric branch, an intelligent diagnosis system for partial discharge detection of 35kV cable and its terminal based on high frequency pulse current method is constructed in this paper. In this paper, the principle, detection method and related experimental conclusions of partial discharge and water tree and electric tree in cable and its terminal are systematically analyzed. According to the possible location of local discharge at 35kV cable terminal, the 1:1 modeling simulation of local discharge defect model with different sizes and shapes is carried out by using finite element method, in order to study the characteristics of field intensity distribution and potential distribution in cable terminal. The mechanism of local discharge in cable terminal is further understood, and the theoretical reference for aging diagnosis is provided. The simulation results show that the break of copper shield layer at cable terminal is the weak link of partial discharge and has high local field strength. In the positions where partial discharge may occur, the cutting defect has greater field strength than the sunken defect, and is more prone to partial discharge. The sharper the shape of the cable terminal defect model is, the more serious the electric field distortion is, and the larger the field strength is. When there are air gap and other defects near the fracture surface of copper shield layer, the local field strength is larger than the air breakdown field strength of 30 kV 鈮，

本文编号：2483928