Influence of Metro OVPD on Stray Current Interference on Buried Pipelines

Taking a metro line and adjacent buried long-distance pipeline as the testing object, the pipeline and track electrical parameters under 4 kinds of over-voltage protection device (OVPD) operating conditions was simultaneously tested. The influence rule of OVPD on the stray current interference on buried pipelines was analyzed, and the distribution rule of rail-to-ground potential and flowing current between rail and ground were clarified. The results show that when the equipment was switched on, the peak current flowing between rail and ground was greater than 1 000 A; the current peak value increased by about 60% when two OVPD were switched on at the same time. When one of OVPD at two ends of a power supply interval was switched on, the rail-to-ground potential at the other end slightly lowered. When the OVPD near the intersection of the rail and the pipeline was switched on, the positive/negative offset of the pipeline potential showed an increasing trend, and the time distribution of inflowing and outflowing stray current did not change significantly; while the remote OVPD was switched on, the proportion of stray current outflow was significantly reduced, and pipeline potential beyond 4 km overall negative shifted, positive offset of the pipeline potential and outflowing current density were suppressed. The OVPD near the intersection of rail and pipeline had a greater effect on the positive offset of the pipeline potential than the remote one, while the effect on the negative offset of the pipeline potential was just the opposite.