Influence of freezing water conductivity on the positive corona performance of soft rime ice-covered conductor

Corona performance of transmission lines in foul weather conditions, icing particularly, have attracted widely attentions recently. In this research, the influence of freezing water conductivity on positive corona performance of soft rime ice-covered conductor is studied in corona cage via energized artificial icing method. The most important finding of this research is that the maximum deviation of the corona inception voltage obtained by the compared three corona inception method could reach 14.7% in soft rime icing condition, and the quadratic law method is recommended. The formed soft rime is composed of the divergent dendritic layer and the ice layer. Based on the ultraviolet photon videos and the corona current pulses waveform, the corona development process of soft rime ice-covered conductor is divided into four stages: feeble discharge mode, positive onset streamer mode, positive glow mode, and positive pre-breakdown streamer mode. Moreover, with higher freezing water conductivity, the obtained icing weight and icing thickness are bigger, consequently, the corresponding corona loss and audible noise are also larger.