Evaluation of a Wind Field Parametrisation Methodology for Lidar-Measured Wind Turbine Inflow

Abstract

There are different methods for the reconstruction of wind fields from lidar measurements, either expressing the wind condition as a set of global parameters, or by 2D or 3D wind vector reconstruction. In this work, we propose a four-parameter wind field parametrisation model as a further development of the three-parameter model introduced by Kapp and Kühn (2014, 2017), which includes a rotor-equivalent wind speed, the horizontal inclination angle of the wind with respect to the measurement plane, a wind shear exponent and a turbulence parameter. In our approach, the turbulence parameter is based on the spatial variations with respect to the rotor-equivalent wind speed over the measurement plane. The model is evaluated by applying it on a spatially and temporally highly resolved SpinnerLidar data set, measured from the nacelle of a wind turbine situated in flat terrain, with a met mast data set for comparison. First results show a good correlation for the rotor-equivalent wind speed and the horizontal inclination, however, a poor fit of the exponential shear. The turbulence parameter follows a physically different definition than the common definition of turbulence intensity, however, the analysis shows that they are weakly correlated with each other. Overall, the model shows potential, but must be further evaluated, e.g. with additional data or simulated lidar measurements within an LES wind field.