计及充放电能量不平衡的储能分组控制策略OA

Configuring energy storage systems in wind farms to rapidly track power fluctuations can enhance the stability of grid-connected wind power.During the power smoothing process,energy storage systems need to frequently switch between charging and discharging to track the high-frequency fluctuations,which causes significant life loss.Adopting a dual energy storage control mode can to some extent alleviate the life loss caused by frequent charging and discharging,thereby extending the operational life of energy storage.However,existing research still has the following deficiencies:(1)The optimal depth of discharge(DOD)of the energy storage system under the dual energy storage control mode is obtained through simulation data,without providing a theoretical analysis result through strict reasoning,resulting in inefficiency and inaccuracy in obtaining the optimal DOD.(2)In the wind-energy storage system,the intrinsic mechanism of the random fluctuation of wind power and the imbalance of charging and discharging energy,as well as the SOC of the dual energy storage,has not been analyzed,and the design of the control strategy under the dual energy storage mode lacks a strict theoretical basis.causing most studies to fail to address the extreme situations where the dual energy storage operates at high/low state of charge(SOC).(3)The imbalance of charging and discharging energy caused by the random fluctuation of wind power during the operation of the dual energy storage has not been effectively solved.Although the first-order low-pass filter time constant control method based on SOC feedback can alleviate the operation of the dual energy storage at high/low SOC,it does not fundamentally overcome the imbalance of charging and discharging energy,and the two energy storage groups cannot operate at the optimal DOD to fully utilize their cycle life.To address these issues,this paper conducts systematic research on the determination of the optimal DOD,the analysis of the operation state at high/low SOC,and the development of a new dual energy storage control mode,and proposes a new energy storage group control strategy considering the imbalance of charging and discharging energy. Firstly,a method for determining the optimal DOD based on the energy storage life function is proposed,which can obtain the operating SOC range that maximizes the service life of different types of energy storage systems.Then,a model of the imbalance of charging and discharging energy in the energy storage system for smoothing wind power is constructed,and the intrinsic mechanism of the extreme situation where the dual energy storage operates at high/low SOC is analyzed,providing a theoretical reference for solving this problem.On this basis,a new dual energy storage control strategy and parameter design method are proposed,which greatly reduces the imbalance of charging and discharging energy,fundamentally solving the problem of the dual energy storage continuously operating at high/low SOC,and adds a power correction link based on the feedback of the imbalance energy,enabling the dual energy storage system to self-adjust to the optimal energy state and fully utilize its operational life.In addition,the proposed strategy is simple in design and has a small amount of calculation,making it easy to apply to real-time smoothing control. Simulation results based on actual wind power data show that:(1)The proposed method for determining the optimal DOD of the dual energy storage system can obtain the operating DOD that maximizes the service life of the energy storage system based on its life function,and this method is universal and can provide theoretical guidance for determining the optimal DOD of different types of energy storage.(2)By deriving the correlation model between the operating state of the dual energy storage system and the smoothing of wind power,the intrinsic mechanism leading to the continuous operation of the dual energy storage system at high/low SOC extreme states is analyzed,providing a theoretical basis for the design of energy storage controllers in the energy storage group control mode.(3)The proposed new dual energy storage control strategy fundamentally solves the extreme situation where the dual energy storage continuously operates at high/low SOC,and enables the two energy storage groups to operate at the optimal SOC,fully utilizing their cycle life,while ensuring that the grid-connected power meets the requirements at all times.The proposed parameter determination approach reduces the number of parameters and simplifies the design process.