关键词: 接触网绝缘子, 泄漏电流, 改进经验模态分解阈值, 信号去噪

Abstract: There is a large number of noise when insulator leakage current of overhead contact system is taken. EMD（Empirical Mode Decomposition） has the problems of end effect and illusive component in actual use. In this paper, similar extrema extension method and the ratio of power method are used to solve the problems existing in EMD, and then, wavelet threshold is combined to de-noise the leakage current. Improved EMD threshold de-noising method and wavelet threshold de-noising method are used respectively to remove the noise from both the simulated leakage current and the leakage current gathered in the high voltage experiment. Estimate the results through the analysis and comparison of three characteristics of the signal pre-and-post de-noised, including effective value, the amplitude value ratio of triple-harmonic to fundamental and signal-to-noise ratio（SNR）. It is shown that similar extrema extension method and the ratio of power method can solve the problems of end effect and illusive component, the de-noising result of de-noising method based on improved EMD threshold method is better than wavelet threshold method. At the same time, improved EMD threshold method is self-adaptive, therefore, is suitable to dirty wet insulator leakage current of overhead contact system de-noising.

Key words: overhead contact system insulator, leakage current, improved Empirical Mode Decomposition（EMD）, signal de-noising