Research On The Power Smoothing Control Strategy Of Flywheel Energy Storage For The Direct-driven Permanent Magnet Wind Turbine

Research on the use of renewable energy is receiving great attention allover the world, mainly due to its relative technology maturation andadvantages for large-scale use, thus wind energy is getting rapiddevelopment. However, the randomness and intermittency of the windspeed will result in wind turbines’ grid-connected power to fluctuatecorresponding to the wind speed. With the expansion of wind farm, thepower fluctuation has greater effect on the stability and economics of thepower grid, and also has impact on the safety of the power grid.This paper puts forward a scheme that uses energy storage equipmentto reduce the effect of wind generator’s grid-connected power fluctuationproblem that is caused by the variations of the wind speed. A big inertiaflywheel is rotated at high speed; the flywheel energy storage device willtransform the electrical energy into kinetic energy through the energyconversion motor. The device has good development prospects in thewind power field because of its advantages that include a high density forenergy storage, relatively high efficiency, produce minimal or nopollution directly and a longer life cycle.Firstly, based on the basic structure and operating principle of theflywheel energy storage, the permanent magnet brushless DC motor ischosen as the driving motor. The double closed-loop control structure ofthe flywheel energy storage device energy control is designed based onthe analysis of the permanent magnet brushless DC motor. In addition, asystem model is built using the Matlab/Simulink software in order toanalyze the charging and discharging process.Secondly, in order to improve the energy storage system control’saccuracy and robustness; based on the fundamentals of fuzzy PID controlalgorithm, this paper adopts the fuzzy adaptive PID control for therotation outer-loop of the flywheel energy storage device’s doubleclosed-loop control system, and the rotation ring fuzzy inference system is put forward. The simulation results show that the control strategy of thecontrol system is valid.Then, the wind machine characteristics are analyzed. The controlstrategy of the dual PWM converter and wind energy’s maximum powertracking control in the direct-drive permanent magnet wind turbine arestudied. The direct-driven wind power unit simulation is built to showthat the established model and control strategy of the wind power unit arevalid.Lastly, a structure with flywheel energy storage system paralleled onthe DC side of the direct-drive permanent magnet wind turbine, and acalculation method of the flywheelenergy storage system’s power are putforward to smooth the wind system’s grid power. The simulation resultsprove that the control strategy is valid.