Multi-train Operation Optimization And Control For Railway Traffic Conflict Detection And Resolution

Rescheduling and train operation control are two core functions of real-time railway traf-fic management.The purpose of rescheduling is to organize train operations,making sure a conflict-free and efficient railway system.Train control aims at regulating train’s speed,making the train run in accordance with its real-time traffic plan.Advanced rescheduling and train control methods are important in intelligentizing the dispatching system,improving the railway efficiency,and ensuring the operation safety.Emergent situations and random factors cause delays,making trains deviate from their traffic plans.How to reschedule trains’ traf-fic plans and regulate trains’ speeds,making trains get back to order,are the main issues for real-time railway traffic management.The dissertation will focus on the situation that trains are deviated from their traffic plans,and study the rescheduling problem and train operation optimization and control problem.The dissertation focuses on the following five aspects:1.A train-group modelling method using timed colored petri nets is studied.The railway topology is formulated with petri nets,using ’places’ to represent stations and blocks,’tokens’ to represent trains,’transitions’ to represent actions of a train moving from one block to anther,and ’arcs’ to present moving directions.Besides,every token is assigned a color to mark train’s number,route and running times,etc..Petri net’s enabling and firing conditions and color sets are settled in accordance with trains’ routes.So that the petri-net based train-group model can simulate train flows along railway network.The train-group model can be used for train operations prediction.2.Conflict detection and resolution method based on the petri net model and heuristic search methods is studied.The conflict detection rules are firstly established in accord-ing to train operation rules.Together with the reachability graph of Petri net,the conflict prediction method is proposed.With reducing secondary delays as the objective func-tion,a conflict resolution method is developed using A*search algorithm and dynamic search window search strategy.The method can produce conflict-free and less-delay new timetables.3.Train trajectory optimization method is developed with multiple-phase optimal control model and pseudospectral method.Train path envelope is adopted to reformulate real-time traffic plan or timetable to time and speed constraints at key points.So that train trajectory calculation model can directly response to real-time traffic plans.Multiple-phase optimal control model is used to formulate the train trajectory optimization prob-lem with energy-saving as the optimization targets,safety,punctuality,riding-comfort as the optimization constraints.Pseudospectral method is used to transfer the multiple-phase optimal control model into an nonlinear programming problem,which is solved with existing nonlinear programming solvers.A computation loop with given initial solutions is designed to improve the computation speed.4.A train speed regulation method with consideration of ATP(Automatic Train Protec-tion)speed protection is studied.Speed protection curve is proposed which links the ATP protection curve and speed limits curves.The method of re-calculating optimal train trajectory is designed for delay situations.Then a two-level speed control loop is proposed with model predictive control method.The control loop makes train’s speed staying below the speed protection curve as well as tracking the optimal train trajectory.5.Train speed control method with consideration of safe tracking is studied.Based on the request of safe tracking,a train speed control is designed which monitors the state of previous train and the distance between two tracking trains.A model predictive control method is used to regulate train’s speed and tracking distance.The train speed control aims at following the optimal speed trajectory,as well as making train’s speed staying below the speed limits and ensuring a safe tracking distance.