Research On Flywheel Energy Storage In Wind Power Generation System Application

Wind in nature are characterized by randomness,intermittency and non-adjustability.The wind power captured by a wind turbine is proportional to the cube of the wind speed.A small change of wind speed will cause a large fluctuation of the wind power.With the large-scale integration of wind power generation system,the negative impact on the power system of our country becomes more and more prominent.The fluctuations of wind power connected to grid will not only significantly affect the stability of power grid voltage and frequency,but also endanger the safe operation of power system,even cause the collapse of the entire power system.Therefore,smoothing the active power output of wind power generation system is not only conducive to the safe operation of the entire power system,but also help to improve the acceptance of the wind power generation system.Firstly,on the basis of summarizing various types of wind power generation system and energy storage equipment,the working principle and mathematical model of permanent magnet direct-driven wind power generation system are studied.The wind speed model and wind turbine model are established.Using MATLAB/Simulink,the permanent magnet direct-drive wind power generation system model is simulated and analyzed,and the influence of wind speed fluctuation on the active power of the wind farm is illustrated.Secondly,the working principle and mathematical model of flywheel energy storage system is introduced,the energy conversion process of flywheel energy storage system is also introduced,and a quick breaker based on high speed repulsion mechanism with opening and closing about 3ms for flywheel energy storage system is proposed.And the space vector pulse width modulation of flywheel energy storage system is introduced.The simulation model of flywheel energy storage system is built by MATLAB/Simulink and the excellent characteristics of flywheel energy storage system are proved to be particularly suitable for the power smooth control of the wind power generation system.The flywheel energy storage system is selected to be installed on the DC side of the wind farm.The speed-current double closed-loop control strategy is proposed for both the flywheel side and the wind farm side converter.The control strategy is based on the grid voltage vector control.The stability and change rate of flywheel energy storage system to the wind farm active power when the wind speed fluctuates are simulated and analyzed by using MATLAB/Simulink.And the good smoothing effect of the proposed control strategy on the wind farm active power is verified.Finally,by comparing the cost of flywheel energy storage to super capacitor storage and superconducting magnetic energy storage at the same energy storage capacity and rated power,the economy of flywheel energy storage system in wind power generation system is further verified.By comparing different rated power of flywheel energy storage system,the smoothing effect of active power of grid-connected wind farms is obtained.The economic rating of wind farms is about 15%of power of wind farms.The economic storage capacity ratio is that can charge and discharge about 15 minutes based on economic rated power.