Research On Optimization Of Distributed Electric Vehicle Energy Storage System

Energy has a crucial role in the development of society and economy.Its development and utilization have also had adverse effects on the environment.Power battery is the power source of electric vehicles.A large number of electric vehicles have considerable storage capacity,which can be used as a load in the power grid can also be used as power,and now the development of electric vehicles provide a new for the development of distributed energy storage.The distributed energy storage system described in this paper is for household micro-grids.The key research contents are as follows: mainly for the accurate estimation of the SOC of the electric vehicle battery pack in the distributed energy storage system and the charging /discharging control strategy for the electric vehicle.Ⅰ、Lithium ion battery SOC estimation study.Firstly,the Least Square Support Vector Machine(LSSVM)and the Differential Evolution algorithm based on probability estimation operator(MBDE)are introduced in detail.The SOC of the single lithium ion battery is estimated by using the two methods.The time,voltage and current data of the 18650 lithium ion battery as the input of the method and the corresponding SOC at all times as the output is to build a model.And use the verification data to verify,we can use this method to estimate the SOC value of a single cell is more accurate.On the basis of this,the paper analyzes the inconsistency of the battery pack,and introduces the definition of the SOC of battery pack and the calculation formula of the SOC estimation of the series lithium ion battery.The MBDE-LSSVM method is used to estimate the SOC of the single lithium ion,then the SOC of the battery pack is estimated.Ⅱ、Electric vehicle charging/discharging control strategy research.At this stage,a two-stage optimization model is established that takes into account not only the cost of the electric vehicle as a grid load,but also the cost of the electric vehicle as a distributed energy storage device and the cost of the battery.On the basis of the optimal cost of the electric car of the user,the second stage model is used to obtain the set of solutions which make the load curve of the grid more smooth.The strategy and the random charging strategy and the minimum cost of charging strategies were compared,respectively,from the cost and load of two aspects of analysis.It can be seen from the simulation results that the charging/discharging control strategy of electric vehicle based on the two-stage model is superior to the random charging strategy and the minimum cost charging strategy,both in terms of cost reduction and smooth load.