Research on Influence of Humidity on Total Electric Field of Unipolar HVDC Line

It is of great significance to study the influence of humidity on total electric field of HVDC transmission lines to realize the differentiated design of transmission lines. In this paper, an outdoor experimental platform is built to study the effects of humidity on ground total electric field under unipolar negative HVDC lines in natural environment. The results show that in natural environment, with the increase of relative humidity, the ground total electric field under negative line increases at first, but when the humidity reaches a certain level, the increase trend of ground total electric field obviously slows down, and the electric field begins to decrease at high humidity. According to the analysis, the increase of relative humidity in natural environment is accompanied by the decrease of temperature, which is the main reason for this experimental phenomenon, that is, the decrease of temperature weakens the increasing trend of total electric field caused by the increase of humidity. The research conclusion can provide reference for transmission line design in different areas.