Effect of Salt Fog on DC Discharge Characteristics of Rod-rod Gaps on High-Altitude Area

In recent years, ultra-high voltage AC and DC power transmission technology has developed rapidly, and some transmission lines have passed through high-altitude salt lakes. Heavy salt and heavily polluted environments directly affect the insulation reliability of key equipment. This article artificially created the high-fog and high-humidity environments with electrical conductivity of 0 (no fog), $500\ \mu\mathrm{S}/\text{cm},\ 3000\ \mu\mathrm{S}/\text{cm}$ , and $6000\ \mu\mathrm{S}/\text{cm}$ in the natural low-pressure environment of Xining area at an altitude of about 2500m. DC discharge characteristics tests of 1m, 1.5m, 2m, 2.5m, and 3m rod-to-rod gaps were carried out. The results show that the discharge voltage increases with the increase of the gap distance in a foggy environment with the same conductivity, and the discharge voltage has a linear relationship with the gap distance; under the same gap distance, the fog water conductivity has no significant effect on the discharge voltage. At the same time, under the same conditions, the gap discharge voltage decreases with an increase of altitude. The conclusions of this paper provide an important basis for the selection of external insulation parameters of transmission lines in high-altitude, salt lake areas.