Study on Energized Mixed-phase Icing of CFCCW and its Effect on AC Corona Onset Voltage

In winters, China witnesses frequent mixed-phase ice disasters, which have a detrimental impact on the secure operation of transmission lines. Most of the studies are focused on the conventional overhead lines, and little attention is paid to the novel carbon fiber composite core wire (CFCCW), which were widely used in recent years. Besides, the influence rule of frequent mixed-phase icing on the corona onset characteristics for CFCCW has not been extensively studied across extant literature. Thus, this article addresses the aforementioned issues by conducting Alternating Current (AC) corona tests for four kinds of CFCCW that would be coated by mixed-phase ice in a low-temperature laboratory. The results showed that the impact of mixed-phase ice on the wire corona onset voltage can be reduced by nearly 50%. With more icing the corona onset voltage would further decrease but at a slower pace. For the wires with a larger diameter, higher corona onset voltage with low distortion in the electric field strength was observed for the same icing time. For the freezing-water conductivity, no significant impact on both the icing morphology and the corona onset voltage was observed. Moreover, the validation for the simulation model was established by comparing the simulation results with the experimental results. These inferences drawn could act as a theoretical reference for transmission lines designing and calculating the wire corona onset voltage in the mixed-phase icing areas.