Evaluation of Rail Potential and Stray Current with Dynamic Traction Networks in Multitrain Subway Systems

In multitrain subway systems, excessive rail potential and stray current (RP-SC) appear in the reflux system during the dynamic operations of an over voltage protection device (OVPD) and a drainage device (DD), which has not been clarified until now and has seriously affected the safe operation of the systems. To accurately evaluate RP-SC with dynamic traction networks, the equivalent method of the reflux system with mixed parameters is proposed, based on which a new simulation model that considers the dynamic characteristics of OVPD and DD is established. The control characteristics of OVPD and DD are analyzed in the established simulation model with multiple trains operating in the dynamic traction network. Dynamic RP-SC are simulated in different cases and are validated in the field tests at Guangzhou Metro Line 2. Results show that the RP-SC with dynamic traction networks can be effectively evaluated by the proposed model. RP-SC are greatly influenced by the dynamic operations of OVPD and DD, and excessive RP-SC can be mitigated by adjusting the grounding resistances of the closed OVPD.