Research On Hybrid Energy Storage Control Strategy And Energy Management For Smoothing Wind Power Fluctuation

In recent years,wind energy has become increasingly involved in the world’s energy mix due to many factors such as climate change mitigation and reduction of energy dependence on fossil fuels.In addition to its clean and renewable advantages,wind energy can exhibit undesired short-term power fluctuations,and its random and intermittent nature can affect power system power quality,reliability and generation scheduling.With the rapid development of energy storage technology,the application of energy storage to smooth out wind power fluctuations has become a new focus due to its maneuverability,convenience and economy.In this paper,we select a hybrid energy storage system(HESS)composed of battery and supercapacitor to start the research on the control strategy and energy management of wind power fluctuation smoothing.The main research contents are as follows:Taking the wind power grid fluctuation standard as the starting point,we discuss the problem of over-smoothing using the traditional wavelet packet method to smoothing wind power,and propose an improved wavelet packet smoothing wind power method combined with the wind power grid standard,which no longer completely filters out the power of high-frequency components at all moments,but only smoothes out the local transgression interval in the time domain to obtain the grid power components that meet the wind power grid standard,and then allocates the highfrequency components in the hybrid The proposed method reduces the accumulated power and the number of charge/discharge switching of the energy storage power command on the basis of meeting the wind power fluctuation standard,which is conducive to reducing the energy storage configuration cost and extending the energy storage life.A model predictive control(MPC)wind power leveling strategy that takes into account the level of battery output and the leveling capacity of supercapacitor is proposed to address the contradiction between energy storage output and leveling capacity in wind power leveling strategy.Then,a fuzzy control(FC)based on the feedback of the battery output and the state of charge(SOC)of the supercapacitor is designed to control the target fuzzy dynamically.The proposed method not only ensures that the battery output is smaller and prolongs the battery life,but also ensures that the supercapacitor has sufficient smoothing ability for wind power sudden changes.A two-layer energy management system(EMS)considering the degradation cost of energy storage is proposed based on the modeling of the degradation cost of energy storage based on the depth of discharge for the economic operation of wind storage systems integrated into the microgrid and the energy management of hybrid energy storage systems.The upper layer schedules power with the objective of minimizing the microgrid operation cost on a large time scale,while the lower layer schedules power on a small time scale with the objective of minimizing the deviation from the optimization results of the upper layer and minimizing the fluctuation caused by the wind power prediction error.The proposed two-layer EMS provides the basis for energy management and hierarchical control scheduling of energy storage after gridconnected wind storage systems.