Browsing by Author "Grau, Patrick"

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    Comparison of linear and nonlinear model predictive control of wind turbines using LIDAR
    (2014) Schlipf, David; Grau, Patrick; Raach, Steffen; Duraiski, Ricardo; Trierweiler, Jorge; Cheng, Po Wen
    Recent developments in remote sensing are offering a promising opportunity to rethink conventional control strategies of wind turbines. With technologies such as LIDAR, the information about the incoming wind field - the main disturbance to the system - can be made available ahead of time. Feedforward control can be easily combined with traditional collective pitch feedback controllers and has been successfully tested on real systems. Nonlinear model predictive controllers adjusting both collective pitch and generator torque can further reduce structural loads in simulations but have higher computational times compared to feedforward or linear model predictive controller. This paper compares a linear and a commercial nonlinear model predictive controller to a baseline controller. On the one hand simulations show that both controller have significant improvements if used along with the preview of the rotor effective wind speed. On the other hand the nonlinear model predictive controller can achieve better results compared to the linear model close to the rated wind speed.
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    Look-ahead cyclic pitch control using LIDAR
    (2010) Schlipf, David; Schuler, Simone; Grau, Patrick; Allgöwer, Frank; Kühn, Martin
    LIDAR (Light detection and ranging) systems are able to provide preview information of wind disturbances at various distances in front of wind turbines. This information can be used to improve the control of wind turbines. This paper compares a predictive feedforward control structure combined with common PI controllers to a baseline controller and to an H∞ approach showing the advantage of look-ahead control to reduce wind turbine loads. The control design is verified by simulations with a turbulent wind field and a full nonlinear model of the wind turbine.