Optimal blade pitch control with realistic preview wind measurements

In above-rated wind speeds, the goal of a wind turbine blade pitch controller is to regulate rotor speed while minimizing structural loads and pitch actuation. This controller is typically feedback-only, relying on a generator speed measurement, and sometimes strain gauges and accelerometers. A preview measurement of the incoming wind speed (from a turbinemounted lidar, for example) allows the addition of feedforward control, which enables improved performance compared to feedback-only control. The performance improvement depends both on the amount of preview time available in the wind speed measurement, and the coherence between the wind measurement and the wind that is actually experienced by the turbine. We show how to design a collective-pitch optimal controller that takes both of these factors into account. Simulation results show significant improvement compared to baseline controllers, and are well correlated with linear-model-based results. Linearmodel-based results show the benefit of preview measurements for various preview times and measurement coherences. Copyright c © 0000 John Wiley & Sons, Ltd.