Effect of atmospheric parameters on AC corona onset voltage of conductors

With the implements of China´s Western Development Project and West-East Power Transmission Project, transmission lines will inevitably pass through high altitude regions with complex atmospheric conditions. Air density and air humidity along the line passages will change much, which will affect the corona discharge performance of conductors. Studies about the effect of air density and air humidity on conductor´s corona onset voltage are not common so far. Neither is there any report on the correction formula of conductor´s corona onset voltage with considering the combined effect of air density and air humidity. In this paper, air density and air humidity are adjusted in an artificial climate chamber and conductor is tested with AC voltage. The result shows that conductor´s corona onset voltage will increase with the increase of relative air density following a power function relation. The corona onset voltage will first increase then decrease with the increase of absolute air humidity. The calculation formula of conductor´s corona onset voltage with considering the combined effect of relative air density and air humidity is obtained.