Optimization Method Of Train Operation Curve Considering Traction Power Supply Characteristics

In recent years,urban rail transit(URT)has been developing rapidly in China because of its advantages such as large capacity,safety,comfort,and convenience.However,the energy consumption problem in URT system is becoming more and more serious.It is important to reduce the operation cost and energy consumption in URT system.Since the energy consumption of train operation accounts for the largest proportion in the energy consumption of URT system,the advanced technology of energy-efficient train operation is studied in this paper,including optimizing the speed profile of a single train and improving the regenerative energy utilization of multiple trains.Urban rail trains can obtain electric energy from both the traction substation and energy exchange with other trains sharing the same traction network.Due to the above-mentioned reason,the structure and characteristics of DC traction power supply system are considered in this paper,and simulation models of traction power supply for single train and multiple trains are established.Then the validity of simulation models is verified by using the practical data from the Yizhuang line of Beijing Subway.The result shows that the energy consumption calculated by the proposed model is more accurate than the traditional method using traction work when comparing with the data in the practical situation.Based on the simulation model of traction power supply,a comprehensive model for speed profile optimization of a single train is constructed,considering the motor efficiency at different speed levels and the influence of voltage fluctuation of traction network on the traction/braking force of the train.The dynamic programning is used to solve the optimal speed profile under the given running time between stations.Moreover,in order to avoid the situation of low efficiency caused by the excessive state space,a strategy is put forward in this paper by designing the "fastest" and "slowest,speed profiles under practical operation situations,which improves the algorithm efficiency.The simulation results show that the energy consumption of optimized speed profile is reduced by 37.7%,thus verifying the effectiveness of the proposed algorithm.On the basis of the single train model,a comprehensive model for two-train speed profile optimization in the same power supply area is constructed,aiming to minimise the total energy consumption of substations.Under the condition of knowing the control strategy of font train,the improved genetic algorithm is developed to solve this two-train comprehensive model.Besides,real coding and adaptive crossover and mutation methods are designed to enhance efficiency.There is a 6.37%and 4.52%decrease in the total energy consumption of substations under two scenarios,respectively.Finally,combined with the study in this paper,a simulation software for urban rail train operation based on traction power supply model is developed in the GUI of MATLAB,which can be used to analyze the energy saving effect of trains with different speed profiles.