Research On Optimization Method Of Operational Energy Consumption Of Hydrogen Fuel Cell Hybrid Electric Tram

The traditional locomotive based on diesel propulsion system has attracted people’s attention to the environment and sustainable development due to its emissions.In order to obtain an environment-friendly railway system,the locomotive based on fuel cell came into being,which has the advantages of high efficiency and environmental protection.The locomotive with fuel cell as the main power source does not need catenary and the third rail,which improves the beauty and safety of the city.In this paper,the methods to reduce the energy consumption of hydrogen fuel cell hybrid electric tram are studiedAccording to the main technical parameters of the tram and the ramp information of the running line,the required power of the tram under various extreme conditions is calculated,so as to obtain the power constraints of the hybrid power system and the capacity constraints of the power battery.According to the train size and axle load constraints,the volume and weight constraints of the power system are obtained.Finally,combined with the bus voltage constraints,the branch definition algorithm is used to solve the number of power sources in the power system.Based on the configuration of the power system,the fuel cell model,boost circuit model,power cell model,three-phase interleaving parallel bidirectional buck boost circuit model,braking resistance model and DC bus demand power model are analyzed and built.At the same time,the control method of boost circuit and bidirectional buck boost circuit and the establishment method of DC bus voltage are studied.A switching method of braking resistor for hybrid power system is proposed,which can control the switching of braking resistor according to the different states of tram.On the basis of the tram power system model,a two-layer operation energy consumption optimization method based on train and power system is proposed,which is mainly divided into two layers.One is the optimization of train operation curve at the top level,which is reflected in the optimization of train demand power,which is determined offline.In this layer,Pontryagin maximum principle is used to deduce and solve the optimization problem of tram running speed curve.For short distance operation,the running curve of tram includes full traction stage,coasting stage and full electric braking stage.In order to satisfy a series of boundary conditions of the optimization problem,this paper uses particle swarm optimization algorithm to search the optimal initial value of the covariate between each station.It is found that the energy consumption of tram after optimization is lower than that before optimization.Although the operation time is increased,it is within the acceptable range.The second is the research on the energy distribution method of the bottom power system,which is carried out in real time during the train operation,which is reflected in the optimization of the equivalent hydrogen consumption of the power system.Because the energy allocation method based on fuzzy logic control relies on expert experience and rule base,it is difficult to achieve the global equivalent hydrogen consumption optimization,and the energy allocation method based on dynamic programming can achieve the global equivalent hydrogen consumption optimization,because of its large amount of calculation,it cannot be controlled online in real time,Therefore,based on the study of the above methods,an energy allocation method based on off-line optimization and on-line operation is proposed.It is found that the proposed energy allocation method can achieve real-time control and lower global hydrogen consumption.In this paper,it is applied to the hybrid electric system of tram.The hardware in the loop simulation platform based on op5600 is built,including the model used to simulate the operation of tram and its power system and the peripheral hardware circuit used for communication,acquisition and control.In the first part,using the overall model of tram power system built in Matlab / Simulink environment,the RT-LAB compiler environment is used to convert the model into machine language and download it to op5600 to simulate the real-time dynamic response of tram.In the second part,the control circuit based on DSP28335 is designed,which is used for the digital to analog conversion circuit between op5600 and DSP.Based on the above hardware,the output distribution method of power source and the control algorithm of DC bus voltage are written in DSP compiler development environment ccs5.0.Finally,the tram power system simulated in RT-LAB platform is controlled,and the energy consumption optimization method proposed in this paper is verified by experiments.The results show that after optimization,the tram runs in the demonstration line condition,and the system equivalent hydrogen energy consumption is reduced by about544.3g.