Nacelle-based Lidar Measurements for the Calibration of a Wake Model at Different Offshore Operating Conditions

Commonly, wake models are calibrated in wind tunnels or using flow simulations with a wide degree of physical details. In general, it is assumed that these methods cannot fully reproduce the real operating conditions of wind turbines. This research aims at investigating the calibration of an analytical single wake model in relation to full-scale measurements. Within this scope, we fitted the wake model to wake measurements realised with a lidar installed on the nacelle of an offshore wind turbine. We studied the parameters returned by the fit separating cases at different levels of atmospheric turbulence and thrust on the wind turbine rotor. Comparing the results with a published calibration based on few LES wind fields representative for partial load conditions, we achieved good agreement when the considered wind turbines operated in similar conditions. For other situations, i.e. at full load, we found different calibrations of the model parameters. Our results show that and how nacelle-based lidar measurements can be complementary in the development of wake models. (C) 2017 The Authors. Published by Elsevier Ltd.