An Overspeed Protection Mechanism for Virtual Coupling in Railway

Abstract

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 paper, 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 paper 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.

A Survey on Control Methods for Virtual Coupling in Railway Operation

“…Safety: Xun [31], [32] designed a coordinated collision mitigation approach for virtually coupled trains by using MPC, with the optimization goal of minimizing the hazard of train collision within the platoon. It is compared with adaptive cruise control and maximum braking control through numerical simulation.…”

“…Able to improve the capability [7], [30] Able to maintain safe operation [31], [32] Suitable for analyzing the stability [33], [34], [35], [36] Suitable for modeling nonlinear optimization control problems [37], [38], [39] D: Computational Intelligent Method Suitable for scenarios where multiple trains converge to form a formation [42] Has the potential to be used in this area…”

Railway Virtual Coupling: A Survey of Emerging Control Techniques

“…3. Su et al [51] and Xun et al [65] used the following expression to determine the desired dynamic gap reference:…”

Research on intelligent formation operation performance of straddle-type rapid transit vehicles in heterogeneous operating environment

“…In terms of the train formation cooperative control method and control algorithm, in order to solve the speed limit calculation in VC and train safety control when overspeed occurs, the calculation methods of limit speed difference based on relative coordinates and a collision mitigation approach by minimizing the relative kinetic energy are pro-posed [3]. Moreover, a variety of model predictive control algorithms are used to construct VC controllers to study cruise control of virtual coupled train sets (VCTS), proving that VC can reduce train spacing while ensuring train safety [4][5].…”