Study On Maximum Wind Energy Tracking Control Of Direct-drive Wind Power System Based On Magnetic-geared Generator

As environment problems andenergy shortagehave gradually attracted people's attention,the importance of the developing clean energyis self-evident.Direct drive wind power generation system has always been one of the main directions of wind power development.However,its application is mainly limited by the volume and weight of the direct drive generator.So,it is necessary to solve the problem,how to improve power density(or the torque density).In this paper,the torque density that magnetic-geared wind power generator provided is equivalent to 2~3 times of the ordinary permanent magnet synchronous motor,which is helpful to reduce the size and weight of generator.In this paper,the magnetic-geared generator,wind turbine and double PWM power converter in the direct drive wind power generation system are introduced and analyzed.According to the principle and the power characteristics of wind turbine,the optimal torque is adopted to realize the maximum wind energy tracking.The magnetic field formation mechanism and operation principle of the magnetic-geared generator are analyzed in detail.The finite element analysis of the model is carried out by using JMAG electromagnetic simulation software.At the same time,the mathematical model of the magnetic-geared generator in different coordinate system is established.In the realization of power AC-DC-AC,vector control strategy of generator side converter is adopted.It means the electromagnetic torque of generatorwhich match the optimal torque of the wind turbine when collecting the maximum power,is adjusted by the converter.Grid side converter adopts the grid voltage vector oriented control strategy.The voltage vector of power after inverted,achieves synchronization with the grid voltage vector.And the working principle of space vector pulse width modulation(SVPWM)is introduced.According to the analysis above,the simulation model of direct drive system is built based on Simulink.Under a given wind speed change,the simulation results show that the generator can track the change of the maximum wind energy,and the power voltage of the grid side inverter can also be synchronized with the grid.