基于HHT的绝缘子泄漏电流分析及放电状态分类识别

Leakage Current Analysis and Classification of Discharge State Identification of Insulator Based on HHT

泄漏电流是污秽绝缘子在线监测参数,能动态地反映绝缘子表面的放电状态。文中开展了瓷绝缘子人工污秽放电试验,利用Hilbert-Huang变换分析了不同污闪阶段的泄漏电流固有模态函数分量、Hilbert边际谱与时频熵,从时频域及波形细节提取了15个特征量,使用主成分分析法与最小二乘支持向量机分类器对污秽放电状态进行识别。结果表明:起始放电阶段与闪络阶段的泄漏电流固有模态函数分量较多;泄漏电流的Hilbert边际谱上频率主要分布在0~150 Hz、200~250 Hz范围内;闪络前泄漏电流的时频熵值总是大于闪络后的;当训练样本数为测试样本数5倍及以上时,分类器的综合评判准确率可达99%,准确实现了污秽放电状态的分类识别。文中研究结果可为建立绝缘子污闪预警系统提供依据。

Leakage current is an on-line monitoring parameter of contaminated insulator,which can dynamically re-flect the discharge state of insulator surface.In this paper,the artificial contamination discharge test of porcelain in-sulator is carried out.The intrinsic mode function components,Hilbert marginal spectrum and time-frequency entro-py of leakage current in different pollution flashover stages are analyzed by using-Hilbert Huang transform.15 charac-teristic quantities are extracted from time-frequency domain and waveform details.The contamination discharge state is identified by using principal component analysis and least squares support vector machine classifier.The results show that there are many components of leakage current intrinsic mode function in the initial discharge stage and flashover stage.The upper frequency of leakage current in Hilbert marginal spectrum is mainly distributed in the range of 0~150 Hz and 200~250 Hz.The time-frequency entropy of leakage current before flashover is always great-er than that after flashover.When the number of training samples is 5 times or more than that of test samples,the comprehensive criteria accuracy of the classifier can reach 99%,and the classification and recognition of contamina-tion discharge state can be realized accurately.The results of this paper can provide a basis for the set up of insulator contamination flashover early warning system.