Transformation and Analysis of Leakage Current for Icing Flashover Prediction of HVDC Outdoor Insulators

The change in the characteristic amount of leakage current is directly related to the surface properties of ice-covered insulators. The measurement of LC can analyze the icing status of insulators and predict the flashover. In this paper, icing and flashover experiments were conducted at CIGELE, and the discharge process on the insulator surface was recorded by a high-speed camera. The LC was denoised using wavelet analysis, and the details, approximate components and surface discharge characteristics of the LC at each stage of the charged icing process were analyzed. It is found that the LC and surface discharge characteristics of the charged insulator during icing can divide the discharge process into three stages, and the discharge frequency is greater at negative voltages. The low-frequency components of LC obtained after wavelet decomposition are mainly influenced by the ice layer characteristics, while the middle and high-frequency components correspond to the air gap discharge pattern.