Robust LMI-Based Control of Wind Turbines with Parametric Uncertainties

This paper considers the design of robust LMI-based controllers for a wind turbine along its entire nominal operating trajectory. The proposed robust controller design takes into account parametric uncertainties in the model using a structured uncertainty description, which makes the controllers less conservative than controllers designed using unstructured uncertainty descriptions. The LMI-based approach enables additional constraints to be included in the design, which is exploited to include requirements for minimizing fatigue loads and actuator usage. Two different methods are adopted, of which the first method assumes full state information and therefore requires a separate observer. In contrast, the second method relies only on output feedback, but introduces complications in the design procedure in order to achieve feasibility in the solution of the control law. Simulation results are obtained that show improved performance of the robust controllers in a comparison with a controller designed based on classical methods.