Battery Management System And Energy Storage Strategy Design Based On AC Microgrid

Owing to the increase of energy demand and the decrease of non-renewable energy reserves,the modern society has been facing with an energy crisis.Because of its high efficiency,no pollution,low loss and high stability,the microgrid which depends on renewable energy sources to generate electricity has been released into use.However,the using of microgrid not only causes the instability of the grid,but also results that the grid cannot consume excess energy from microgrid.In order to ensure the safety and economy of microgrid,this paper designs the grid-mode(connected to utility grid)energy storage control strategy based on the SOC(State of Charge),different electricity consumption period of the grid and short-term load forecasting,to achieve the micro-grid operation of the economy and security,and realize peak load shifting for the grid.Design and implementation of the BMS(Battery Management System),focusing on the estimation of the battery SOC,provide data basis to microgrid energy storage control strategy.The main research contents include:(1)Three-phase AC microgrid energy storage system is designed.Adding BMS in the energy storage system to monitor the battery status in real time,and then,provide data basis for energy storage control strategy.(2)The SOC estimation of battery is realized.The extended Kalman Filter(EKF)algorithm and the Unscented Kalman Filter(UKF)algorithm are studied,and are applied to the estimation of battery SOC,the performance is compared by MATLAB simulation.It is verified that EKF and UKF tracking effect is good,the error is small,the estimation effect is good.Compared to EKF,UKF algorithm is stable,the error is smaller,the effect is better.(3)Design and Implementation of BMS.Completed the battery voltage,temperature,battery current collection,and battery equalization through the dissipation of the way,SOC estimation,fault detection,and communication between BMS and the host computer.BMS not only to achieve the protection of the battery,but also for microgrid energy storage control strategy to provide data support.(4)Energy storage control strategy design in grid mode.Based on the different electricity consumption period of the grid,SOC,and daily load forecasting,the energy storage system control strategy of grid mode is designed.According to the different electricity consumption period of the grid and the SOC chose battery charge or discharge;according to daily load forecasting to determine the value of charge or discharge power.To achieve the peak period of electricity consumption,as far as possible to sell electricity to the grid in order to obtain economic benefits;in the electricity low ebb period,as far as possible to purchase electricity from the grid,stored up;in the flat load's period,according to the next period of electricity consumption,select the appropriate strategy.Both to achieve the safe operation of the microgrid,and realize peak load shifting.