Lidar-based reconstruction of wind fields and application for wind turbine control
In this thesis horizontal, upwind scanning lidar systems of the focused continuous-wave type are regarded for wind turbines. The theory of wind field reconstruction is extended to a five parameter model describing the inflow in non-uniform conditions more accurately. Sensor requirements are derived. A new approach to spherically scan the inflow area is studied experimentally. Expected inaccuracies of the averaged wind direction signal in a wind farm environment are quantified and spatial inhomogeneities are analysed.
The use of inflow lidar measurements in feedforward blade pitch control is holistically modelled and simulated. As a supplement to individual feedback pitch control, lidar-based feedforward collective pitch control reduces damage equivalent loads, extreme loads, power output fluctuations and pitch activity significantly.