基于EMD时频熵的绝缘子泄漏电流特征量的研究

绝缘子的泄漏电流和绝缘子的健康状况密切相关,可以综合反映污秽程度、受潮程度、绝缘子承受电压以及绝缘子缺陷等因素。泄漏电流中含有丰富的绝缘子运行状况的信息,它的时频熵可以描述时频平面上频谱能量分布的均匀性。根据泄漏电流不同发展阶段时频熵的分布情况,提出用EMD方法得到的时频熵作为特征量对绝缘子健康状况进行评估和预测。通过实验,得到了随着RH变化的时频熵值。根据它的变化,可以得到绝缘子的污秽情况;同时将其与同等条件下的三次谐波与基波的幅值比进行对比,显示了它的合理性。

Time-Frequency Entropy Characteristics for Insulator Leakage Current Based on EMD

Insulator leakage current is the comprehensive reflection of the various factors related with insulator condition,namely,status of contamination,degree of humidity,voltage load and insulation defect.Insulator operation information is largely conveyed in the leakage current;in particular,its time-frequency entropy can describe the uniformity of the spectral energy distribution on the time-frequency plane.According to the time-frequency entropy distribution of leakage current at different development stages,this paper proposes that the EMD-based time-frequency entropy be adopted as characteristic parameter to assess and predict the condition of insulator.Through the experiment,the time-frequency entropy is extracted changing with relative humidity(RH).Thereby,the contamination status of the insulator can be identified;meanwhile,compared with the amplitude ratio between the third harmonic and fundamental wave in the same condition,the time-frequency entropy is verified to be reasonable.