Locating Current Leakage Point of Subway and HVDC with Multi Components Geoelectrical Potential Monitoring

Significant disturbances of stray currents caused by subway leakage and unbalanced high-voltage direct current (HVDC) have a significant impact on grounded motors. To obtain the subway leakage current and HVDC ground current, two types of multi-pole distance devices with 6/8 electrodes for orthogonal combination are used. The template matching method is applied to identify the spontaneous potential (SP) pulses generated by subway train start/stop, and daily variation correction is utilized to determine geoelectric field (GEF) step changes caused by HVDC. The results show that (1) the number of SP pulses picked up after template matching corresponds to the number of running trains and the combination of pulses from multiple component orientations reflects the orientation of leakage point; (2) the method for locating current leakage sources can identify the positions of two HVDC converter stations after daily variation correction by analyzing the GEF observation from numerous stations; (3) there are slight dissimilarities between the HVDC simulation and GEF observation due to local electromagnetic environment and electrical structure factors. Therefore, accurate signals of orthogonal observation and positioning methods are crucial for confirming the interference source; after correction in the normal signals, results of good electromagnetic observation can be obtained.