| The modern tram system is an important part of urban public transport.In recent years,it has been greatly developed in the world.In order to eliminate the negative effect of traction net on urban beauty,some cities adopt on-board energy storage technology in their modern trams to reduce the laying of overhead traction wire.However,the tram system cannot be fully satisfied by a single energy storage device.Hybrid energy storage system(HESS)is a solution to solve the shortcomings of a single energy storage system in the tram field.Based on this background,this paper studies the optimization of sizing and energy management strategy for HESS combining batteries and supercapacitors in modern tram.Firstly,the principle and characteristics of the topological structure of HESS and energy storage devices for modern tram are analyzed in detail,and the load power is calculated based on the parameters of Wuhan tram line T1,which provides a theoretical basis for the study of energy management optimization of trams.Secondly,an optimization method of HESS sizing based on NSGA-II is proposed.This method can obtain the multi-objective Pareto solution by entering the results of traction calculation in different scenarios.It not only shows the change of target function values under different sizing results,but also can obtain the optimal solution by adding specific constraints.In addition,the topological structure and the sizing results of HESS are analyzed in detail by changing the distance between the tram stations.Besides,because of the special right-of-way of tram,this paper presents an energy management strategy(EMS)of HESS based on V2I communication.Based on the operation status of trams,the EMS is optimized offline by dynamic programming algorithm(DP)to obtain the optimal power distribution coefficient.In actual operation,the tramcar obtains the prediction of the running status through the V2I communication and obtains the corresponding power distribution coefficient through the look-up table to realize the online adjustment of the EMS.The paper verifies the superiority of this strategy compared with a rule-based strategy through simulations.Finally,a comparative experiment of different EMSs was completed through the HESS prototype of tram.In this paper,a control strategy based on virtual battery current is proposed to realize the proportional power distribution of HESS.The upper monitor is redesigned to realize the function of the upper computer to adjust the ratio coefficient of power distribution.The power of tramcar is scaled,and the validity of the online EMS proposed in this paper is validated under different operating and load conditions. |
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