Modeling And Simulation Of Flywheel Energy Storage System Applied In Wind Turbine

With the development of fossil energy crisis,air pollution and other problems,in recent years the new energy resources have developed rapidly worldwide.Among the new resources,wind power resource gradually becomes the main resource of power generation in the world because it is relatively abundant and wind-generated electricity is becoming increasingly competitive on price,performance and reliability.The characteristics of wind speed,like randomness and intermittence and other natures,result in the unstable output of the wind turbine.Therefore,no matter to the small independent wind power system to big grid-connected wind power crew,applying energy storage device plays an indispensable role in ensuring the load work safely and in improving the quality of power supply.Compared with the chemical battery,pumping and super capacitor energy storage,flywheel energy storage has distinctive advantages,such as high storage density,long service life,low requirement for the environment,low maintenance cost,etc.This thesis researches on the modeling and simulation in the light of the flywheel power storage system and its application characteristics in wind power generation system,therefore the selected topic has relatively high practical significance.In this thesis,the author proposes an overall topological structure of flywheel storage system that could be applied into the wind power generation system based on the previous discussion of the wind power generation system,the principle of flywheel energy storage system,and relevant mathematical models.The author also respectively builds a simulation model of the wind power generation system and the flywheel energy storage system in the environment of MATLAB/Simulink.In addition,the devices of flywheel energy storage are connected into the independent and the grid-connected wind power system.Simulation models are built respectively for the two situations,and then the operating characteristics of the system are analyzed deeply.Considering that the flywheel has three working modes during operation,i.e.the charging mode,the discharge mode and the hold mode,the flywheel charging system utilizes the double closed-loop control module by speed and electric current,and the current closed-loop control is realized through the speed control module,the hall signal measurement module.While in the process of discharging,the system uses the double closed-loop control module with voltage in the outer loop and speed in the inner loop,and with the decline of the revolving speed of the flywheel ontology and the counter EMF,boost chopper circuit is added to stabilize the output voltage in order to ensure the stability of generator voltage.Simulation results show that in the independent wind power generation system,connecting flywheel energy storage devices into the DC load terminal could help to store the excess energy when the wind speed is high and to release electricity when the wind speed is slow to ensure the normal work of the load under rated voltage.In the grid-connected wind power generation system,when the fluctuation of the grid is higher,compensating the active and reactive power by connecting flywheel energy storage system before the network side could effectively reduce the impact on the system.