Research On Hybrid Energy Storage System Apply To AC Electrified Railway

Railway electrification system has been taking up an important position in Chinese transportation.In recent years,high-speed railway also had a notable development.As a large industrial electrical power consumer,electrified railway traction power loads are unstable to the power grid.Regenerative braking energy created by engine braking also brings problems with power quality to the power grid,which directly influence the economic profit of the railway department.At the same time,people are paying more attention to power regeneration and efficiently reusing.The key to solve above problems is to efficiently reuse regenerative braking power to stabilize voltage fluctuation.One of the critical points is to create an energy storage system for AC electrified railway.Nowadays,there are various types of energy storage technologies.Different kinds of energy storage systems have already been used in railway applications and research.Still limited by technology development,most systems are using single energy storage methods like batteries and supercapacitors.This article will focus on combining advantages in different energy storage systems in AC electrified railway,and give out a plan of a hybrid energy storage system.Firstly,this article discusses the necessity of an energy storage system in AC electrified railway.Also basic theories are analyzed,including development and advantages of energy storage technology.Then,the combination of battery technology which is deeply developed and FESS(flywheel energy storage system)which is fast developing,is decided to be used as basic theory support.Single supply arm connected to ground in the substation is used to build up the system.Then,by sufficient analysis of structural features of FESS and battery,equivalent circuit model is built to calculate specific parameters.Based on performance characteristics of this system,more analysis will be shown in this article on engine control method of FESS,the motor side converter,the battery side bi-directional DC/DC converter.Next,more research is done on input and output control strategy of hybrid energy storage system.Based on physical characteristics of battery and FESS,power is efficiently distributed on different parts,and the topology of the whole structure is created.Then,the design is verified feasible by MATLAB/Simulink modeling.Finally,real test of hybrid energy storage system is simulated under true environment of Beijng-Tianjin city railway,and the result is significant.By comprehensive evaluation on saving electricity costs and device costs,analysis on hybrid energy storage system economical profit is given out.