Analysis of positive DC corona inception voltage of stranded conductor at different altitudes

This paper is aimed at analyzing the inception voltage of positive direct current (DC) corona at different altitudes for the stranded conductor to ground structure. An improved numerical method which combines the corona onset criterion involving the action of photoionization and the improved charge simulation method is presented. The effect of altitude on the inception voltage and the electric field in the vicinity of the stranded conductor are involved in the numerical method. The validity of the presented method is demonstrated through the experiment carried out in artificial climate laboratory. In the experiment, the highest simulated altitude reached 4500 m which may cover the main range of altitudes that the UHVDC transmission lines pass through in China. Furthermore, the roughness coefficient of stranded conductor is discussed in this paper.