Coordinating Analysis of Leakage Current and Arc Development for Icing Flashover Prediction of HVDC Outdoor Insulators

The leakage current (LC) is directly related to the discharge process on outdoor insulator surface, which is considered as one of critical measurements for flashover prediction of ice-covered insulators. This paper conducts icing flashover experiments in an artificial cold room and uses a high-speed camera to photograph the dynamic process of the discharge arcs. Image processing techniques were applied to extract the arc perimeter. The characteristics of the LC and the arc perimeter were analyzed at each stage of the DC icing flashover process, as well as the relationship between the arc perimeter and the LC during the arc development. The results reveal that the varying characteristics of LC and arc perimeter under DC voltages effectively separate the three stages of arc growth. The negative DC voltage causes the higher discharge activities. Taking the three arc extension periods during arc discharge process under positive DC voltage as examples, the LC and arc perimeter rise synchronously and have a high correlation during these periods. When the LC is low, the linear fitting is poor, while the linear fitting is better prior to the flashover.