Optimization on the Dynamic Train Coupling Process in High-Speed Railway

This work focuses on the driving strategy optimization problem of a scenario in which two trains come from two branches under virtual coupling, aiming at going through the junction area efficiently. A distance-discrete optimal control model is constructed. The optimization objective is to maximize the trip time during which the two trains operate in coupled state. The line conditions, dynamic properties of the trains and the safety protection constraints are considered. The nonlinear constraints are converted into linear constraints with piecewise affine function and logical variables, and the proposed problem is converted into mixed integer linear programming (MILP) problem which can be solved by existing solvers such as Cplex. Four simulation experiments are conducted to verify the effectiveness of MILP. The dynamic programming (DP) algorithm is used as the benchmark algorithm in the case study. Compared with DP algorithm in small state space, MILP has better performance since it shortens the coupling time. Moreover, the improvement of line capacity of virtual coupling is 35.42% compared with the fixed blocking system.