Research On Characteristics Of Leakage Current Of EHV Transmission Line Iced Insulator Strings

Ice is a special kind of contamination, and the flashover mechanism of iced insulator is similar with the polluted insulators, both of which are caused by the leakage current. For the variation of the leakage current is the dominating factor of flashover, the comprehensive monitoring the development and variation trend is not only beneficial to analyze of the flashover mechanism, but also to build a warning model for the flashover of the iced insulators. The500kV transmission line insulator test is based on the artificial climate laboratory of UHV AC test base of SGCC. After the collection of large amount of test data, the leakage current characteristic in the ice flashover process is analyzed. The paper mainly covers the following three aspects:first, divide the leakage current into sections according to the relationship between the development of leakage current and arc. Then in order to study the time and frequency characteristics, the maximum value power spectrum and harmonic characteristics are analyzed.lt obtains the differences between the flashover leakage current and the withstanding leakage current.Finally, the bi-spectrum method is applied to analyzed the bi-spectrum equal height value and the bi-spectrum three dimensional chart to gain the bi-spectrum characteristic of the leakage current in different period. Results show that with the development of insulator discharge, bi-spectrum leakage current increases obviously,and the second phase coupling range becomes larger...