Periodic Disturbance Accommodating Control for Speed Regulation of Wind Turbines

Performance of a model-based periodic gain controller is presented using Disturbance Accommodating Control (DAC) techniques to estimate fluctuating wind disturbances. Operation is restricted to speed regulation using Independent Blade pitch Control (IBC) and by measuring only rotor angle and speed. The modeled turbine is a free-yaw, two-bladed, teetered rotor machine with simple blade and tower flexibility — 6 discrete degrees of freedom. A comparison is made to a time-invariant DAC controller, constructed by various approaches. Results indicate that the two controllers perform nearly identically, despite the inherent periodic dynamics in the system. The best time-invariant state estimator model was designed by freezing the periodic plant at a specified rotor azimuth position.