Rail Potential and Stray Current Mitigation for Urban Rail Transit With Multiple Trains Under Multiple Conditions

As one of the nonneglectable challenges in urban rail transit, rail potential and stray current issues may cause metallic corrosions and electronic shocks, which endangers the safety of the traction power system. Hence, a zero-resistance converter system (ZRCS), parallel to a conventional traction power system (CON-TPS), is introduced for mitigating rail potential and stray current. By establishing zero-resistance loops for the train current, its return path on running rails is shortened. Since multiple trains operate in the up-line and down-line, this article proposes the ZRCS share method in both lines. The control strategy based on rail-section detection and relevant operation principles of ZRCS is analyzed in detail with considering multiple trains under multiple conditions. Moreover, ZRCS does not affect the operational reliability of CON-TPS considering its independence from CON-TPS. The locations of switch units (SUs) in ZRCS are optimized to improve the mitigation performance of ZRCS. Both simulation and experimental results prove that zero-resistance loops are established by ZRCS in the up-line and down-line, and their rail potential and stray current are mitigated obviously.