乙丙橡胶电缆终端气隙局部放电过程及特征提取

高速列车乙丙橡胶（ethylene propylene rubber，EPR）电缆终端由于制作、安装不规范，导致终端内部出现气隙，气隙部位的局部放电将严重影响高速列车的正常运行. 为了分析气隙缺陷下25 kV乙丙橡胶电缆的局部放电过程及特性，制作了含气隙缺陷的电缆试样，测量了试样自起始放电至击穿全过程的放电参量及局部放电相位（phase resolved partial discharge，PRPD）谱图发展过程，并基于Gaussian金字塔与灰度共生矩阵的方法对放电全过程的PRPD谱图进行了特征提取. 研究表明:根据放电参量的变化规律，可将整个放电过程分为放电发展阶段、放电持续阶段、临近击穿阶段；基于各阶段的PRPD谱图呈现的不同形貌，使用多尺度的灰度共生矩阵方法提取出的角二阶矩、熵、对比度等特征可用于放电阶段的表征. 

Partial Discharge Process and Feature Extraction of Air Gap in EPR Cable Terminal

Due to the nonstandard manufacturing and installation of the ethylene propylene rubber (EPR) cable terminal for high-speed railways, air gap appears in the terminal, and the partial discharge at the air gap seriously affects the normal operation of high-speed trains. In order to analyze the partial discharge process and characteristics of the 25 kV EPR cable with air-gap defects, a cable sample with air-gap defects was fabricated. The discharge parameters and the development process of phase resolved partial discharge (PRPD) spectrum were measured from the initial discharge to sample breakdown. Based on the Gaussian pyramid and gray-level co-occurrence matrix, the PRPD spectrum of the whole discharge process is extracted. The results show that according to the change of discharge parameters, the whole discharge process can be divided into discharge development stage, discharge duration stage, and near-breakdown stage. Based on the different morphology of PRPD spectrum in each stage, the second-order angular moment, entropy, contrast and the like are extracted by the multi-scale gray-level co-occurrence matrix method and can be used to characterize the discharge stage.