Abstract: In order to study the influence of HVDC transmission on the geoelectric field in Linfen and Xiaxian seismic station of southern Shanxi Province, the variation patterns and characteristics of the interference on the geoelectric field observation are analyzed. Combined with the mechanism of HVDC transmission interference, the influence of different ground electrode on the same station and the influence of the same ground electrode region on different stations are quantitatively calculated and analyzed. The results show that: ① When the local electric field observation data are disturbed by HVDC transmission lines, the geoelectric field will be distorted, and the typical forms are square wave and square wave with sharp peak. The variation characteristics of the additional electric field signals observed by different stations are very different for different HVDC transmission lines. ② The earth loop current caused by the HVDC transmission line may have certain influence on the observation data of geoelectric field. The observation data of long and short pole distance in the same direction at the same station affected by the same HVDC transmission line have the same direction and the interference amplitude is basically the same. ③ When the HVDC transmission line fault causes the earth loop current, the interference of different stations is inversely proportional to the square of the distance between the ground electrode and the station, and is also affected by the conductivity of the station.

Key words: Geoelectric field observation, HVDC transmission, Interference analysis