Research On Optimization Of High-speed Train Timetables Considering Energy Saving

At present,the "four vertical and four horizontal" high-speed rail network has been fully completed,and the "eight vertical and eight horizontal" high-speed rail network is taking shape.However,the problem of operating energy consumption and cost increasing year by year should also be paid enough attention to.High-speed rail is an important symbol of modern "green transportation" and a key field to achieve carbon peak and carbon neutrality.Therefore,it is of great practical significance to explore the energy-saving operation methods of high-speed trains.On the basis of the research achievements of domestic and foreign scholars on energysaving timetables,this paper takes high-speed railway trains as the research object,puts forward the energy-saving optimization method of high-speed railway train timetables,and constructs the optimal allocation model of interval running time,the energy-saving schedule model of train with regenerative braking energy utilization,and the cooperative optimization model of energy-saving timetables and EMU operation plan respectively.In the Python environment,Lagrange relaxation algorithm,simulated annealing algorithm and Gurobi solver were respectively used to solve the problem.Finally,a case study was carried out with the background of Baoji-Lanzhou high-speed railway line.The main research contents of this paper are as follows:(1)Aiming at the problem of reassigning interval running time to reduce the traction energy consumption of trains running between continuous stations,and considering that the existing research only takes single train as the research object,a new method of synchronizing time allocation of multi-train interval running time combining with schedule adjustment is proposed.Based on the "four-stage" control strategy adopted by high-speed trains between stations,the optimal driving strategy set was constructed.The conversion position of tractor-cruise,cruiseidle-run and idle-braking conditions was taken as the decision variable,and the traction energy consumption and interval running time were divided into calculation objectives to solve the linear relationship between traction energy consumption and interval running time in the optimal driving strategy set.On this basis,a multi-train interval operating time optimal allocation model is built.The model takes the minimum traction energy consumption as the goal,and considers the constraints of the total running time and decision variables of the multitrain entire multi-interval.The constraint on the total running time of multi-train interval is a complex constraint with coupling characteristics.The Lagrangian relaxation algorithm is applied to integrate the constraint into the objective function,so that the model is decomposed into sub-problems that can be solved independently in multiple intervals,which realizes the goal of synchronizing the running time allocation of multi-train interval and makes up for the shortcomings of the existing research.Taking Baoji-Lanzhou high-speed Railway as the background,the calculation process and results show that the proposed method has high calculation efficiency,a total of 595.958 KWH traction energy saving rate of 1.2%.From the perspective of schedule analysis,the energy saving method through the fine-tuning interval operation has a small impact on the range and range,which has strong practical significance.(2)The "four-stage" driving strategy is adopted when the high-speed train runs between stations,among which the traction stage and regenerative braking stage are respectively the "energy consumption" stage and the "capacity" stage.Making full use of the regenerative braking energy generated by the "capacity" stage can not only effectively reduce the traction energy consumption of the train,but also reduce the network pressure fluctuation of the traction network.Taking the time of first station departure and stop time of high-speed train as decision variables,considering the constraints of EMU traffic and the safety constraints of running diagram,the energy-saving schedule model of high-speed train was established with the optimization objective of maximum utilization of regenerative braking energy.A simulated annealing algorithm based on adaptive large-scale neighborhood search strategy was designed by adding the interval forward failure operator and interval backward failure operator.Finally,taking the Baoji-Lanzhou high-speed Railway as the background,the calculation results show that the schedule optimization model mentioned in the paper can make the regenerative braking energy utilization rate reach 49.3% within the acceptable calculation time,which verifies the effectiveness of the model and the algorithm.(3)From the perspectives of reducing traction energy consumption,increasing the utilization rate of regenerative braking energy and improving the use efficiency of EMU,a collaborative optimization method of energy-saving running diagram and EMU use plan of high-speed trains was proposed.Firstly,the train operation process was divided into several driving intervals with the stop as the breakpoint,and the linear relationship between traction energy consumption within the driving interval and the interval running time was obtained by adjusting the position of the working condition transition point.On this basis,the optimal allocation model of multi-train interval running time was constructed with the optimization objective of minimizing traction energy consumption,and the KKT condition was used to solve the problem.Secondly,taking the departure time of train starting station,stop time and the selection of train number undertaken by EMU as decision variables,and considering the constraint conditions such as variable value,safe train operation interval time and EMU traffic,a collaborative optimization model of the maximum utilization of regenerative braking energy and the use efficiency of EMU is constructed.This model is a multi-objective mixed integer programming model.Use the Gurobi solver to solve.Finally,taking Baoji-Lanzhou high-speed Railway as the background,the calculation results show that the total traction energy consumption of all trains reduces by 1.2% after the operation time of the reallocation interval,the solved energy-saving schedule regenerative braking energy utilization rate is 68.3%,the average service efficiency of EMU is 82.8%,and the energy-saving effect is remarkable.