Research On Capacity Optimization Configuration And Control Of Hybrid Energy Storage System In Wind-Storage Microgrid

Due to the increasingly serious energy consumption and environmental problems,new energy technology has developed rapidly.In particular,the new energy technology based on wind power has been favored by more experts and scholars.In recent years,the domestic wind curtailment rate has declined rapidly and the grid-connected capacity has increased year by year.However,wind power’s characteristics of volatility and anti-peaking bring great challenges to the wind-storage microgrid system output tracking and regulating plan.Energy storage has been widely used in various fields of the power system as a key technology to cope with the development of new energy and achieve the goal of "double carbon" because of its increasingly mature technology and its ability to improve grid-connected fluctuations.In order to improve the fluctuation of wind power grid connection,solve the peak regulation pressure and the single problem of energy storage operation mode,this thesis takes the hybrid energy storage system(HESS)in the wind-storage microgrid as the research object and conducts some studies on the capacity optimization configuration of energy storage,energy storage peak and valley filling and two-mode coordinated control of wind storage system.Firstly,the wind storage microgrid structure of HESS and various HESS topological and working principle are briefly introduced.Then,the structure and working principle of batteries and supercapacitors are described in detail,and the equivalent circuit model are established according to the characteristics of the two energy storage equipment,the respective charge discharge characteristics are analyzed by model simulation.Secondly,the wind power fluctuation characteristics of grid-connected and the access mode of wind farm energy storage are analyzed,and the centralized access to energy storage is considered.The reference power of hybrid energy storage and target grid-connected power are obtained by low-pass filtering,and reconstructed into low-frequency and high-frequency components through variational mode decomposition(VMD),which are smoothed by the battery and supercapacitor.On this basis,a capacity optimization configuration model for smoothing wind power fluctuations is established,adaptive particle swarm optimization(APSO)is used to solve the allocation of energy storage capacity,and the unified optimization of dividing point and annual comprehensive cost is realized.In addition,according to the typical daily load curve,an optimization model for energy storage to participate in peak shaving of the power grid is established,on the basis of existing constant power control strategy,this thesis proposes power-difference control strategy,in which the actual constraints are considered.Then,through the simulation of the two control strategies,the effect of the power-difference control strategy on peak and valley filling and the effectiveness of charge and discharge control are comparatively analyzed.Finally,in view of the single operation mode and the low utilization rate of energy storage system,a coordinated control strategy using HESS is proposed,in which two operation modes of smoothing fluctuation and peak-valley arbitrage are combined.For the mode of smoothing fluctuation,the internal primary dispensing is performed by VMD decomposition,and then secondary correction of power is realized combined with the state of charge(SOC)of the energy storage.For the mode of peak-valley arbitrage,based on the time-of-use electricity price mechanism,according to the SOC and load information,the energy storage charging and discharging status is determined.Based on this,two operating mode judgment mechanisms and switching control scheme are designed to realize the reasonable management of the windstorage microgrid system.Then,a corresponding example simulation is established in MATLAB to verify the accuracy and effectiveness of the control strategy.