Effect of atmospheric factors on AC corona inception voltage of conductors and its correction

Variation of air temperature, pressure and humidity along the line corridor in high altitude area will affect the corona characteristics of conductors. However, the research on comprehensive effects of these atmospheric factors is rare. Therefore, AC corona discharge experiments on four kinds of smooth conductors with different diameter are performed in large-scale artificial climate chamber where air temperature, pressure and humidity can be adjusted. Experimental results indicate that the effect of variation of air temperature on corona inception voltage is not obvious when air pressure and absolute humidity keep constant. With the increase of absolute humidity, the effect of air pressure on corona inception voltage will reduce, shows such feasturs that in region of low humidity, corona inception voltage increases slowly with the increase of absolute humidity, and good accordance is achieved between the measured and calculated results, while in region of high humidity, corona inception voltage decreases, and the difference between the measured and calculated results is big due to condensation on conductor, which distorts the surface electric field of conductors. Besides, The calculation formula and predicting method for corona inception voltage are presented, with conductor diameter, air pressure and humidity considered.