Analysis on Characteristics of Influence of HVDC on Geoelectric Field Observation

A number of high voltage direct current(HVDC) transmission projects have been put into operation nationwide with the implementation of the basic strategy of "power transmission from West to East, mutual supply between South and North, and nationwide interconnection" in China, which causes increasingly prominent interference on geoelectric field observation. Thus, we summarize the characteristics and laws of interference from HVDC transmission system in geoelectric field stations throughout the country. The typical interference patterns are statistically generalized, including square wave, sharp peak and square wave + sharp peak, among which square wave is dominant, accounting for about 65.5%. In addition, the causes and influence mechanisms of different interference patterns are discussed through theoretical deduction and interference examples. It is concluded that the interference pattern is square wave in the near ground electrode region, sharp peak in the line center region, and square wave + sharp peak in the overlap region. At last, by comparing different interference events of the same line, we analyze the relationships between the interference characteristics and the relative position of the station and the HVDC line, the distance from the electrode, and the underground structure of the affected area, which provides the basis for identifying and judging such interference.