Designing pitch controller for large wind turbines via LMI techniques

This paper proposes a design of robust LMI-based collective pitch controllers (CPC) for large wind turbines operating above their rated wind speeds. The proposed controller design takes into account model uncertainties by designing a controller based on a polytopic model. The LMI-based approach allows additional constraints to be included in the design (e.g. H _∞ problem, H₂ problem, H₂/H _∞ trade-off criteria, and pole clustering). These constrains are exploited to include requirements for perfect regulation, efficient disturbance rejection, and permissible actuator usage. The proposed controller is combined with individual pitch controller (IPC) that reduces the periodic blade's load by alleviating once per revolution (1P) frequency fatigue loads.