Modeling and Control of Rail Potential With Partial Backflow Obstruction in DC Metro Systems

Running rails are employed as the reflux conductor in DC metro systems, whose longitudinal resistance and joint resistance usually increase with the operating years of the system. Subsequently, the partial backflow obstruction occurs, which will greatly increase rail potential (RP) and endanger the security of the metro line operation. In this paper, a dynamic calculation model of DC metro systems with coupled multiple reflux paths is proposed to study the effect and control method of partial backflow obstruction. Firstly, the dynamic simulation model with coupled multiple reflux paths of DC metro is proposed, and the equivalent chain circuit and unified node admittance matrix are established with partial backflow obstruction. Secondly, the effect of backflow obstruction in DC metro systems is studied for the first time with multiple trains operating in Guangzhou Metro Line 2. Thirdly, the control method of partial backflow obstruction with parallel low‐resistance reflux conductors is proposed, and the effectiveness of the control method is analyzed. Results show that partial backflow obstruction will seriously raise the dynamic RP in nearby sections, and the parallel low‐resistance reflux conductors can effectively restrain the influence of backflow obstruction.