Experimental Research on the Corona Inception Field of HVDC Conductor Under Different Air Pressure

When HVDC transmission lines pass through high-altitude areas, the impact of low pressure will cause a change in the corona inception field of the wires. Through simulation experiments, The influence of air pressure on the corona inception field of DC conductor can be obtained, providing data support for the electromagnetic environment prediction of HVDC transmission lines in high-altitude areas. In this paper, A wire-plate electrode experimental platform is established in the artificial climate chamber with controllable temperature, humidity and pressure. An experiment on the influence of air pressure on the corona inception field of DC conductor is carried out by using the wire with diameters of 3mm and 5mm, The experiment involved measuring the ground electric field under positive and negative polarity wires at altitudes ranging from 0 to 4000m. The corona onset voltage of the wire is determined using a fitting method based on the ground electric field data under different pressures, and the corona inception field of the wires is calculated accordingly. The experimental results show that with the increase of altitude (the decrease of air pressure), the corona inception field of the same diameter wire approximately presents a linear decline trend. The linear function can be used to reflect the relationship between the corona inception field and the change of air pressure. The larger the radius of the conductor, the smaller the absolute value of the slope <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$k$</tex> in the linear fitting function, the corona inception field on the surface of the conductor decreases at a slower rate with increasing altitude. In other words, for every 1000m increase in altitude, there is a smaller decrease in corona inception field.