Modeling And Simulation On Hybrid Energy Storage System In DC Traction Power Supply System

With the development of the urban rail transit, the rational use of renewable energy is more and more important. In order to make use of the regenerative braking energy efficiently, energy storage technology has gradually become a hot spot in urban rail transit. The hybrid energy storage technology base on super-capacitor and battery has been used in electric vehicles, new energy power generation technology, micro network etc. Compared to the single device using super-capacitor, the hybrid energy storage system has been developed rapidly since the super-capacitor and battery have a very strong complementarity in the technology. The hybrid energy storage system in traction substation was studies in the thesis, it would provide technical support for the development of hybrid energy storage system using in the urban rail transit field.Firstly this paper introduces the DC traction power supply system model of each component, including the traction substation, contact line, railway and the train in order to build network model of the traditional DC traction power supply system and analyze the principle and the solution. Then the article analyzes the working principle of the hybrid energy storage system, and its mathematical modeling, including the system topology structure, model of charge and discharge condition. HESS mainly uses the ideal voltage source to model, it was added in the traditional model with the solution of modified nodal approach.It analyzes the working condition and connection of the HESS and the rectifier to establish the energy management system which manage the condition of HESS, the charge and discharge procedure of the super-capacitor and the battery, distribution of the energy. Power supply system energy management make preliminary judgment of HESS’s working condition based on conditions including charge, discharge voltage threshold and whether install storage device. According to the HESS’s working condition, it adjusted the rectifier unit’s working state. The HESS energy control strategy control the procedure of super-capacitor and battery’s charge and discharge based on the principles including the SoC security scope and super-capacitor’s priority response.Finally, it added the HESS model and energy management in DC traction power supply system simulation platform(DCTPS) and make the dynamic simulation of urban railway traction power supply system considering HESS in multi-train cases after using the results of traction calculation, train diagram and setting simulation parameters of each system., With the simulation result, we evaluate the HESS and make selection of the capacity in system level. The simulation results show that energy management strategy is effective, reasonable and achieve the energy-saving emission reduction effect.