Study On Hybrid Energy Storage Control Strategy And Capacity Allocation To Stabilize Wind Power Fluctuation

Because the wind power has the characteristics of fluctuation and intermittence,the output power of large-scale wind farm is directly incorporated into the power grid,which will affect the stability and reliability of power system operation.Energy storage system can quickly and accurately compensate the energy required for the system to achieve energy balance and stability control.Due to the limitation of physical conditions,a single energy storage medium can not meet the stabilization task of wind power fluctuation.The hybrid energy storage system has the advantages of various energy storage mediums,which can better meet the requirement of stabilizing wind power.Technology is one of the effective means to stabilize the fluctuation of wind power.The key to the application of hybrid energy storage system is whether there is reasonable control strategy and effective capacity configuration method.The effective control strategy is designed to distribute the power between the energy storage media of the hybrid energy storage system reasonably and make the hybrid energy storage system to be in good running state,which has strong ability to stabilize the wind power.A reasonable capacity allocation method was developed to optimize the capacity allocation of hybrid energy storage system based on the requirement of wind power fluctuation.The topological structure and working principle of the hybrid energy storage system are introduced.The charge and discharge characteristics of the super-capacitor and the storage battery are studied,and the fluctuation characteristics and amplitude-frequency characteristics of the wind power output power at different time scales are analyzed.Based on the analysis of the fluctuation characteristics of wind power output,the wavelet packet method is used to decompose the wind power output to smooth the wind power output.According to the working characteristics of different energy storage media,a mixed energy storage control strategy with timing consideration is developed and the respective advantages of energy storage medium are brought into play.Considering the economy and operating life of the hybrid energy storage system,a multi-objective function model of hybrid energy storage system cost and battery charge-discharge conversion frequency is established.The optimal capacity of two kinds of energy storage mediums,which meet the requirements of wind power fluctuation stabilization,is studied with the objective of minimizing the cost of hybrid energy storage system and the number of charge/discharge cycles.The optimization process of the capacity configuration of the hybrid energy storage system is simulated and analyzed.The influence of different energy storage modes on the hybrid energy storage system and the stabilization effect of the wind power output are analyzed.