Analysis Of Influencing Factors On Speed Profile Of Metro Trains And Its Energy Saving Optimization

With the rapid development of rail transit in China, energy consumption has increased significantly. The train energy-saving operation plays an important role in reducing energy consumption of rail transit system. The speed profile optimization of trains is one of method of train energy-saving operation, which is the reference speed profile for trains to follow in limits of safety and punctuation, making the minimum energy consumption. In this paper, some works related to optimization of speed profile has been done as follows:First of all, a theoretical proof of relationship between energy consumption and trip time for train energy efficient control is given. The maximum and minimum energy consumption are calculated in conditions of free running time. Simulations are presented with parameters of resistance function from actual metro trains.Secondly, the influence of train load on the optimal speed profile is studied. The resistance parameters of various train loads were calculated based on passenger information of Nanjing Metro Line 1 and corresponding optimal speed profiles were generated and compared with each other. Train load estimation and resistance parameters are obtained through the identification of train acceleration. As a result, optimal speed profiles were generated with the identified parameters.Thirdly, an optimization method is proposed for inter-station running time distribution of a train. As the track between two stations always has some different speed limits, the inter-station track can be divided into several intervals based on the number and values of the speed limits which influence the speed profile directly. The function of consumption and running time of each interval can be calculated through function fitting. An augmented objective function is established via Lagrange multiplier. Simulation results are obtained by the Quasi-Newton Method and tested based on CMC (Control Model on Chips) simulation platform.Finally, multi-train cooperation method is given. To absorb the regenerative braking energy in metro power supply section, a multi-train cooperation module is built,then surplus regenerative braking energy distribution method is given and the method to optimize typical speed profile is proposed. A simulation is presented based on Beijing Yizhuang metro line, where cooperation of three trains are realized to absorb the regenerative braking energy.