Research On Energy Management Strategy Based On Power Loss Optimization Of Hybrid Energy Storage Tram

In recent years,through the rapid economic development,the process of urbanization has been accelerating.With the consequent problems of traffic congestion and environmental pollution caused by automobile exhaust emissions,it has become a problem for sustainable development of large-scale cities.More and more cities began to vigorously develop public transportation.As a result of combining energy storage technology and tram technology,hybrid energy storage trams have many features such as energy saving,environmental protection,and beautiful appearance without a catenary.They have quickly become a research focus at demestic and abroad.This paper focus on hybrid energy storage electric tram with lithium batteries and super capacitors as power sourcesis and is studied for its power system topology,power system model,and energy management strategy.Themain contributions obtained in this dissertation are as follows.(1)According to the operating characteristics of hybrid energy-storage trams,four typical topology structures of the existing hybrid power system are compared and analyzedand choose the topologystructure from the four aspects of dynamic performance,system efficiency,economy and control effect etc.Based on the analysis of the tram dynamics,a tram dynamic model was established,and the traction power calculation is completed with reference to an existing tram line data.(2)The power loss during the energy transmission process of hybrid energy storage trams is studied deeply,and the power loss models of lithium batteries,supercapacitors and converters are established according to the tram parameters and the topology of the hybrid power system.Based on the above power loss model,a tram power loss evaluation system is further established.(3)According to the established model,a hybrid energy storage tram system simulation model is built in Matlab / Simulink,and three energy management strategies are developed on the premise of satisfying the performance and safety of the tram system.Firstly,a simple and reliable energy management strategy based on power tracking control is proposed based on dynamic performance,recovered braking power requirements,and power and energy characteristics of energy storage elements.Then,according to the load demand power and the state of the energy storage system,the fuzzy subset is divided,and based on the experience of experts,an energy management strategy based on fuzzy logic control is proposed.Finally,on the basis of meeting the load power requirements and considering the state of the energy storage system,from the perspective of reducing system power loss and improving system efficiency,a dynamic degree of hybrid online convex optimization energy management strategy is proposed..(4)Based on the established experimental platform for the simulation of hybrid energy storage tram systems,the three previously developed energy management strategies are simulated and verified from the power source power allocation range,power source SOC status,system power loss,and system instantaneous efficiency.The performance of three previously proposed energy management strategies are compared and analyzed.The analysis results show that the energy management strategy based on dynamic degree of hybrid online convex optimizationproposed in this paper is more reasonable and flexible,which not only effectively reduces system power consumption,improves system efficiency,but also has good practicability and significant energy saving effects.