Negative Resistance Converter Traction Power System for Reducing Rail Potential and Stray Current in the Urban Rail Transit

In the urban rail transit, the rail current leaks into the earth inevitably due to the incomplete rail-to-earth insulation. It then forms rail potential and stray current issues, which endanger the personal safety and cause metallic corrosions on running rails and the third-party infrastructures. For mitigating the rail potential and stray current, this article proposes a negative resistance converter traction power system (NRC-TPS) to reduce their generating sources by providing zero-resistance loops to the rail current. NRC-TPS is constructed by installing power electronics equipment directly in the conventional traction power system (CON-TPS) without modifying trains, rails, or tunnels, and so on. The operation principles, control strategies, and mitigation performance of NRC-TPS are discussed in detail. The modeling, simulation, and experimental results indicate that the rail potential and stray current are reduced in NRC-TPS compared with those of CON-TPS. The feasibility and practicability of NRC-TPS are also proved through these results.