| With the increasing shortage of traditional energy and the deteriorating environment,the development of new energy has been greatly promoted,and its power generation scale is also rising rapidly.Meanwhile,the random and intermittent characteristics of wind power output have more and more serious adverse effects on the power system.To solve this problem,energy storage technology is widely used.Among them,energy storage and power storage have complementary advantages,and good energy storage characteristics can be obtained by using them together.Power type energy storage is typical of supercapacitors,while energy type energy storage mainly includes lead-acid battery,lithium battery and liquid flow battery.Different mixed energy storage has different influences on capacity configuration.This paper mainly focuses on three hybrid energy storage systems,namely lead-acid battery-super capacitor,lithium battery-super capacitor and liquid flow battery-super capacitor,to study the problem of wind energy storage and capacity optimization.The main research contents are as follows:Firstly,the development trend of new energy generation is analyzed,and the basic theory of electric hybrid energy storage system and grid-connected mode are discussed.A comprehensive summary of the current research status at home and abroad is made,and a wind farm equivalent model is established.At the same time,the working principle and equivalent model of lead-acid battery,lithium-ion battery,liquid flow battery and super capacitor are studied respectively,which provides a reference for the follow-up research.Secondly,a power distribution strategy based on variational mode decomposition and sliding average method is designed.Firstly,adaptive sliding average decomposition is used to suppress the wind farm output that does not meet the requirements of power fluctuation.Secondly,variational mode decomposition of hybrid energy storage power is carried out to obtain low and high frequency power signals and realize primary distribution of hybrid energy storage power.Finally,the overlimit monitoring of the supercapacitor is carried out,and fuzzy control is carried out to meet the charge constraint.Numerical analysis shows that the proposed method has a significant effect on the wind farm output power fluctuation,and at the same time ensures the rational distribution of the internal power of the hybrid energy storage,so that the energy storage system can run more safely and stably.Thirdly,aiming at three different kinds of hybrid energy storage,a model of capacity optimization allocation of hybrid storage system based on two-layer programming is proposed.The upper layer model takes the minimum cost of the whole life cycle of the energy storage life planning cycle as the objective function,while the lower layer takes the minimum day-ahead running cost of the hybrid energy storage system as the objective function according to the configuration information of the upper layer,and obtains the optimal running data of each typical day.By comparing and analyzing the data of rated capacity,power and life cycle cost of hybrid storage under seven different configuration modes,it is proved that the hybrid storage system combining energy storage and power storage has economic advantages over the single type of energy storage,and it is concluded that adopting the hybrid energy storage of accumulator and super capacitor can further strengthen the economy of the system. |
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