Nonlinear control of wind turbines: An approach based on switched linear systems and feedback linearization

The main contribution of this paper is the development of a nonlinear control technique for the control of individual wind turbines in a wind farm. For this purpose, a control scheme based on feedback linearization and gain scheduled linear quadratic regulator (LQR) is applied to a horizontal axis, variable speed, pitch regulated wind turbine. As a result of the physical constraints of their components, wind turbines operate at different control modes with different control objectives. To capture this hybrid nature, a flexible modeling framework based on the notion of hybrid systems is introduced, and the developed controller is designed so as to operate in all modes and over a wide range of wind speeds. The performance and the efficiency of the proposed approach is validated via simulations, and is compared with standard LQR approaches.