Control of a wind turbine using several linear robust controllers

A method to control a wind turbine over a wide range of wind velocities is presented in this paper. Because of the strong nonlinearity of a wind turbine along the wind velocity range several linear robust controllers are applied. Each linear controller has been designed to meet the specifications for the part of the wind velocity range a controller belongs to. Dependent on the wind velocity the appropriate controller is scheduled. Special attention is given to avoiding the harmful transients which arise after switching between controllers. This is done by conditioning the linear controllers which are not in the control loop. Together with some additional specific actions a controller has been synthesized which satisfies the specifications of the controlled wind turbine for the whole range of wind velocities