The Research On Capacity Optimal Allocation Of Wind Farm Hybrid Energy Storage System Based On Variational Mode Decomposition

As the "carbon emissions" issue continues to increase its impact on the global climate,countries will also shift their focus from traditional fossil energy to the development and utilization of clean energy.As the most technologically mature and complete wind power generation among new energy sources,its development and utilization have received extensive attention.At present,the integration of large-scale wind power into the power system has become a general trend.However,as the penetration rate of wind power continues to increase,the inherent volatility and uncertainty of wind power will also affect the safety and stability of grid operation,and to a certain extent limit the large-scale consumption of wind power.Taking into account the characteristics of flexible energy storage configuration and fast power throughput,a hybrid energy storage system composed of energy storage devices with different output characteristics is used,and it is configured on the side of the wind power plant to form a wind storage combined system,which can effectively increase the electrical energy of gridconnected wind power Quality and improve the consumption of wind power.Therefore,this article focuses on the research on the capacity optimization configuration of the hybrid energy storage system,so that it can smooth the power fluctuations in a variety of complex wind power scenarios,and improve the power quality of wind power grid-connected.This article first summarizes the operating characteristics of different types of energy storage equipment and the structure of the hybrid energy storage system,and builds a combined wind storage system based on hybrid energy storage.By considering the complementary output characteristics,configuration cost and flexibility,it is determined to build a hybrid energy storage system that can smooth high/low frequency fluctuations by using power supercapacitors and lithium batteries.Connect the hybrid energy storage system to the wind farm with a common AC bus topology to construct a combined wind storage system.Through the construction of a combined wind storage system based on hybrid energy storage,the fluctuating power of wind power and the response frequency of energy storage are obtained,which provides original data support for the configuration of hybrid energy storage capacity.Then,it compares the mainstream frequency division methods and analyzes the mathematical mechanism and step flow to determine the variational modal decomposition as the frequency division method in complex wind power operation scenarios.By comparing the three basic frequency division theories of wavelet packet decomposition,empirical mode decomposition,and variational modal decomposition,it is expounded and simulated to demonstrate that the variational modal decomposition(VMD)can effectively reduce the dependence of the decomposition process on the initial value and Modal aliasing effectively improves the frequency division effect.Aiming at the direct influence of the number of modes in the variational modal decomposition on the frequency division effect,a variational modal decomposition hybrid energy storage capacity optimization configuration method based on the adaptive modal number is proposed.This method can adaptively determine the number of decomposition layers based on the given unbalanced power of wind power and the quantized frequency points of energy storage equipment parameters,and obtain high-frequency components and lowfrequency components,which are respectively allocated to the corresponding energy storage equipment,and According to the high-frequency power distribution curve borne by the super capacitor and the low-frequency power distribution curve borne by the lithium battery,the power configuration and capacity configuration of the hybrid energy storage system are calculated.Finally,the typical historical statistical data of wind power from a wind farm in Yancheng,Jiangsu Province is used for simulation verification.The method described in this paper compares simulation analysis with the empirical mode decomposition method.The simulation results show that the hybrid capacity optimization configuration method based on adaptive modal number VMD is more in line with the output characteristics of the hybrid energy storage system in terms of power distribution,and is beneficial to improve the hybrid storage system.The operating life of the energy system,and at the same time,the method effectively reduces the configuration scale of the hybrid energy storage system,improves the economy of the wind storage system,and is conducive to the large-scale consumption of wind power.