  In this paper, an approach for active power control of individual wind
turbines is presented. State-of-the-art controllers typically employ separate
control loops for torque and pitch control. In contrast, we use a multivariable
control approach. In detail, active power control is achieved by using
reference trajectories for generator speed, generator torque, and pitch angle
such that a desired power demand is met if weather conditions allow. Then, a
linear quadratic (LQ) optimal controller is used for reference tracking. In an
OpenFAST simulation environment, the controller is compared to a
state-of-the-art approach. The simulations show a similar active power tracking
performance, while the LQ optimal controller results in lower mechanical wear.
Moreover, the presented approach exhibits good reference tracking and by
improving the reference trajectory generation further performance increases can
be expected.
