Energy-saving Optimization And Collaborative Control Of Hydrogen Fuel Cell Trams

Hydrogen fuel cell trams operate by combining a fuel cell as the main power source with a high energy density supercapacitor energy storage system,aiming to absorb braking energy,improve the fuel cell performance index,and extend the life of the hybrid system.However,the complex energy management of the multi-source power system and the coordination and cooperation problems during the whole vehicle operation restrict the application and development of trams in the field of rail transportation.Therefore,the following work is carried out to solve the above problems:First,to address the randomness and non-sequential nature of the tram driving process,a tram state transfer probability matrix is constructed and the next moment demand power distribution is predicted with the help of a two-dimensional Markov chain considering speed and demand power,and then the proposed method is verified to be able to predict the actual tram operating scenario with high accuracy through error analysis;subsequently,the fuel cell operating spectrum is extracted and classified into high load,idle speed and low load operating Then,the proposed method is able to predict the life time of the fuel cell by calculating the number of start-stop cycles and load changes,and comparing the results with the traditional test methods,the accuracy of the results is high,which verifies that the proposed method can save time and test cost while ensuring the accuracy.Secondly,when the traditional Pontryagin’s minimal value principle is applied to the energy management of fuel cell hybrid trams,there are problems of poor real-time and working condition adaptability due to the need to know the future working condition,so a strategy combining global optimization and real-time working condition construction is proposed.Based on the principle of minimal value,the global optimal reference output power of fuel cell is obtained under the constraint of ensuring the load demand and avoiding the wide range fluctuation of State of Charge(SOC)of supercapacitor,with the goal of minimizing hydrogen consumption.The proposed strategy,the conventional minimum value principle and the equivalent hydrogen consumption minimization strategy are compared and analyzed online in typical and atypical driving conditions of trams.The results show that the proposed strategy can improve the robustness of the hybrid system to cope with high power load surges,effectively reduce the number of fuel cell starts and stops,and achieve global and real-time optimal power allocation.Finally,in order to alleviate the congestion problem at intersections,a social vehicle,tram and pedestrian model considering road environment information is established based on a hierarchical road structure to lay the foundation for the further proposed distributed vehicle cooperative control strategy under interactive right-of-way.A new phase is introduced with trams as a necessary condition for guiding and activating the new phase for the convoy formed by them and social vehicles;secondly,a vehicle-level distributed coordination strategy is proposed to satisfy the scalability of traffic control and the smooth flow of vehicles at intersections by calculating the intersection signal timing.Simulation results for three intersection scenarios with different straight and turning demands show that the proposed strategy is effective in reducing vehicle delays at intersections.