Relevant Criteria for Testing the Quality of Models for Turbulent Wind Speed Fluctuations

Abstract

Seeking relevant criteria for testing the quality of turbulence models, the scale of turbulence and the gust factor have been estimated from data and compared with predictions from first-order models of these two quantities. It is found that the mean of the measured length scales is approximately 10% smaller than the IEC model for wind turbine hub height levels. The mean is only marginally dependent on trends in time series. It is also found that the coefficient of variation of the measured length scales is about 50%. 3s and 10s preaveraging of wind speed data are relevant for megawatt-size wind turbines when seeking wind characteristics that correspond to one blade and the entire rotor, respectively. For heights exceeding 50–60m, the gust factor increases with wind speed. For heights larger than 60–80m, present assumptions on the value of the gust factor are significantly conservative, both for 3s and 10s preaverages. The usually applied value of kp≈3 should probably be reduced.