Design Of Battery Management System For All-Vanadium Flow Energy Storage Power Station

With the gradual improvement of social productivity,the demand for energy in people’s production and life is increasing.And people are trying every means to develop renewable energy such as solar energy,wind energy,geothermal energy to replace non-renewable fossil energy as the leading energy source and convert new energy into electricity.Therefore,large-scale energy storage technology,as the lifeblood of the widespread use of renewable energy,has drawn great attention from researchers in various countries.At present,the all-vanadium flow battery is the first choice for large-scale energy storage batteries.It has many advantages such as long service life,no pollution,good safety,high cost performance and flexible conFig.uration.The battery management system(BMS)is an important part of the energy storage system.It can ensure the efficient,stable and safe operation of the energy storage system.Among them,the estimation of battery state of charge(SOC)and energy balance management are the main tasks of BMS.However,due to the large scale of the vanadium liquid flow energy storage power station,the internal reactions are complex and changeable,and it is difficult to describe,which brings great difficulties to the design of the BMS.Existing methods for estimating the state of charge(SOC)of a battery have the disadvantages of cumulative error and lack of self-adaptability;the existing equalization algorithms have disadvantages such as over-equalization and short duration.This thesis addresses the shortcomings of the above two aspects of BMS and does the following:First,a bus-type energy storage system structure is proposed,and the energy storage system is regarded as a multi-agent system.Based on the above system characteristics,a battery energy balancing system model based on multi-agent consistency and a control method model for system time delay compensation are established.A single cell model for battery SOC estimation was established,and the least square method with forgetting factor was used for parameter identification.A comprehensive model of all-vanadium flow battery energy storage system was established to improve the efficiency of the energy storage system and ensure the safe and stable operation of the system.Then,the influencing factors of SOC size,the commonly used SOC estimation methods and their advantages and disadvantages are analyzed.The SOC estimation method based on real-time error correction is proposed for the first time.Compared with other commonly used methods,this method has better real-time performance and higher estimation accuracy.The effectiveness and superiority of this innovative method were proved by simulation experiments.At last,Research the charging balance of energy storage system with SOC balance as the goal.First,the fuzzy control method is used to control the charge balance of the battery pack,and it points out that it cannot suppress the system’s possible overshoot and other shortcomings,and then proposes a double-loop structure equalization method based on information feedback.In order to solve the system delay problem,fuzzy logic system is used to compensate for the unknown delay,and an adaptive fuzzy tracking controller is designed to achieve the targeted equalization of the system and further improve the equalization efficiency.In this paper,the SOC estimation method proposed above can quickly and accurately estimate the battery SOC in a battery pack,and the effect is better than other methods.At the same time,the proposed battery energy balance algorithm can also quickly and effectively solve the energy balance problem of the energy storage system,reduce the energy loss of the system,and extend the service life.