Research On The Leakage Current Characteristics Of Insulators

The study of on-line detecting method for porcelain insulators is important to improve the safety of the power system.Based on the results of a large numbers of artificial contamination experimentation, the interaction of leakage current (under running voltage) and ESDD, CSDD, RH, temperature is analyzed in detail. In this paper, on-line detection for different insulators based on pulse current method is studied. The constituent parts and the realization of the detecting system are introduced. In laboratory, the partial discharge pulse current characteristics of the composite insulators have been studied. The results indicate that partial discharge pulses mainly occur between 60o ~120o and 240o ~ 300o in power frequency phrase. The amplitude of impulse current, the number of the impulse and the phase scope where occurs increase along with the development of the insulator deterioration.The laboratory data is inevitably influenced by high-frequency noise. Based on the wavelet theory, the matlab is used to de-noise the Gaussian white noise by wavelet decomposition and wavelet reconstruction, hence the data approaches the actual value. The following data processing and analysis is guaranteed.The leakage current characteristic under certain voltage is determined by the contamination, relative humidity and temperature. Based on the results of a large numbers of artificial contamination experimentation, the relation between leakage current harmonic component, the phase angle and the surface contamination, relative humidity, temperature is studied. The experiment results state that as the contamination and the RH increases, the ratio of the triple-harmonic in first-harmonic of the leakage current is also rising. The insulator is capacitive reactance in the dry contaminated environment and impedance in the wet contaminated environment.