Effects of temperature and humidity on ground total electric field under HVDC lines

Abstract The characteristics of ground total electric field of HVDC transmission lines impacted by temperature and humidity are of significance in line design and environmental protection assessment. In this paper, an experimental setup encompassing wire-plate electrodes is built, and the effects of temperature and humidity on the ground total electric field under HVDC lines are studied under three conditions: constant temperature with variable humidity, constant humidity with variable temperature, and coupling change of temperature and humidity. The experimental results show that when the temperature and humidity increase separately, the ground total electric field increases, and it is of polarity dependence. When the coupling change of temperature and humidity in natural environment is simulated, that is, with the increase of relative humidity and decrease of temperature, the ground total electric field increases when the HVDC line is in positive corona, and it increases first and then decreases when the line is in negative corona. An important inference from the results is that the characteristics of ground total electric field obtained under the conditions that temperature and humidity change separately are not applicable for the analysis of ground total electric field in natural environment where temperature and humidity vary simultaneously.