An Overspeed Protection Mechanism for Virtual Coupling in Railway

As a new technology to improve transportation capacity by compressing train tracking interval, virtual coupling (VC) has attracted significant attention from both industry and academia. The traditional overspeed protection mechanism cannot guarantee the safe running for a train fleet. Therefore, in this article, we study two key problems of the overspeed protection mechanism: the limit speed calculation and the safe control for the protection of train in the formation when overspeed occurs. This article describes the calculation methods of limit speed difference (LSD) based on relative coordinates and a collision mitigation approach by minimizing the relative kinetic energy, respectively. Finally, the effectiveness of the proposed method is verified through numerical analysis. The proposed calculation method of limit speed can realize large headway at low speed and small headway at high speed, which can meet the time requirement of switch and route arrangement in station areas. The performance of the model predictive control (MPC) based approach is compared with other two control strategies, i.e. basic adaptive cruise control (ACC) and directly maximum braking control (DBC). The simulation results show that the MPC strategy has the best performance among these three strategies in reducing the total relative kinetic energy of virtually-coupled train formation, followed by the DBC control strategy, and the basic ACC control strategy needs to be improved.