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Li H.,Zhangjiajie Electrical Power Bureau of Hunan Power Grid | Li Y.,Zhangjiajie Electrical Power Bureau of Hunan Power Grid | Li Y.,Hunan University | Li J.-Q.,Central South University of forestry and Technology | And 2 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2012

Through making AC tests under ambient temperature, this paper studies the time-domain variation rule of facing flashed leakage impulse current on the surface of iced insulators under different voltage levels at different ice-melting stages. The nonlinear properties of leakage pulse current at various stages are analyzed by using nonlinear dynamics theoretics, meanwhile, by comparing the wave amplitude changes and the largest Lyapunov Index(LE), the change characteristics of the insulator surface's lakeage pulse current for various ice-melting processes are deduced, and the results show that they take on dissimilar nonlinear properties for the lakeage discharge pulse waveform under different voltage level at different ice-melting stages, therefore, throught which a new diagnostic method to monitor the faults for iced insulators is proposed. Source

Li Y.,Hunan University | Zhou Y.,Hunan University | Zhong H.,Hunan University | Wu Z.-Q.,Hunan University | And 3 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

The traditional leakage current's time-frequency analysis method has some insufficiencies. Through dynamic measuring leakage current on the 3-piece string iced insulators at ice-melting stage in artificial climate chamber, this paper proposed that uses frame segmentation method to calculate the reference values; the extreme value of short-time energy signal and zero-cross signal. Through using wavelet decomposition reconstructing the envelope curves of energy signal and zero-cross signal, provides early warning for iced insulators flashover fault from both data and curve aspects. Source

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