Research on Torque Ripple Reduction of Direct-drive Permanent Magnet Wind Power System

In order to solve the problem caused by the torque ripple generation of wind power system, this paper proposed a combined control strategy of individual variable pitch based on blade azimuth angle weight coefficient assignment and generator harmonic reduction. A harmonic voltage compensation controller is designed to eliminate the effect of the harmonic current on the electromagnetic torque, and meanwhile the individual pitch controller is used to balance the aerodynamic torque ripple. The simulation results show that the combined control strategy can eliminate the high harmonics of the generator and restrain the fluctuation of the electromagnetic torque and the aerodynamic torque, and also make the output torque of the wind turbine smoother at the rated working range. The results validate the effectiveness of the proposed design strategy for wind power control system.