Capturing wind turbine power curve and dynamics by atmospheric-like inflow at lab-scale
Creators: name: Neuhaus, Lars
name: Berger, Frederik
name: Peinke, Joachim
name: Hölling, Michael
Publisher: name: Zenodo
Year: 2019
Subjects: model wind turbine
Langevin power curve
active grid
turbulence

description: To test concepts and controls of wind turbines under atmospheric-like inflow conditions at lab-scale, a method is developed in the turbulent wind tunnel of the University of Oldenburg. Commonly, wind turbine models are investigated in wind tunnels under stationary conditions with constant mean velocities. In the atmospheric boundary layer, the flow is unsteady and more complex situations occur. Normally, new concepts cannot be tested under such conditions in the wind tunnel. The herein presented method allows for generating atmospheric-like inflow situations in the wind tunnel and thereby capturing wind turbine power curves and dynamics at lab-scale.<br> In this study, the 3 x 3m² active grid in the Oldenburg wind tunnel [1] and the model wind turbine with 1.8 m diameter (MoWiTO 1.8 [2]) are used. The wind velocity is changed by continuously varying the fan speed. To be close to the velocity distribution in the atmospheric boundary layer, the generated wind velocity by the fans is Weibull distributed. Additionally, the active grid generates a certain statistic of the flow (TI, intermittency). The turbulence intensity is calculated based on 10s sections and found to be constant for the most probable velocities. For higher velocities the turbulence intensity is slightly decreased. The generation and hence the velocity time series is completely reproduceable.<br> This tailored continuous variation of the mean wind velocity in combination with a constant statistic (turbulence intensity) allows to generate atmospheric-like turbulence in the wind tunnel. A 30 minutes velocity time series (corresponding to 25h in free field) generated like this in the wind tunnel can be used to measure the full power curve of a model wind turbine. In addition to the common estimated power curves based on 10-minute averages, also dynamic effects, e.g. of turbine controls, can be studied. To do so, the Langevin power curve analysis is used [3].<br> The presented method therefore allows for an easy test procedure to investigate the general behavior of a wind turbine under realistic atmospheric-like conditions. In combination with the Langevin power curve analysis this is giving insight into dynamic effects. This allows for extensive investigations of different concepts of control and design, such as leading edges slats on the rotor blades (part of the SmartBlades2 project), in the wind tunnel under realistic reproduceable atmospheric-like conditions. [1] Kröger et al.,<em> J. Phys.: Conf. Ser. </em><strong>1037</strong>, 052002, (2018).<br> [2] Berger et al., <em>J. Phys.: Conf. Ser.</em> <strong>1104</strong>, 012026, (2018).<br> [3] Wächter et al., <em>J. Wind Energy</em> <strong>14</strong>, (2011).
description: {"references": ["Kr\u00f6ger et al., J. Phys.: Conf. Ser. 1037, 052002, (2018).", "Berger et al., J. Phys.: Conf. Ser. 1104, 012026, (2018)", "W\u00e4chter et al., J. Wind Energy 14, (2011)."]}