ECN publication
Ontwikkeling en validatie van een stochastisch windbelastingsmodel. Deel 3. Validatie
Published by: Publication date:
ECN 1-12-1997
ECN report number: Document type:
ECN-C--96-098 ECN publication
Number of pages: Full text:
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The validation of a model of normal wind conditions for wind turbinedesign fatigue load calculations is described. The model is proposed in volume 1 of this report, based on stochastic wind field simulation, complies with the IEC 1400-1 standard and should be accepted by the Dutch Design Code as an alternative for the gust model of the Dutch Handbook Wind Data for Wind Turbine Design, Version 3. To validate the wind load model fatigue life time load spectra of the blade root bending moments are calculated for three turbines ranging from 150 kW to 1 MW. These load spectra are compared with measured load spectra and calculated load spectra based on the Dutch Handbook. Additional comparisons are made with Handbook load spectra of five other bending moments, viz. the blade bending moments at mid span, the tilting moment at the top and the base of the tower and the tower torsion moment. It is concluded that the wind load model based on the IEC 1400-1 standard is capable of producing reliable design load spectra which compare well with measurements and Handbook calculations if: (1) at least the two horizontal velocity components of the turbulent wind field are simulated; (2) the von Karman turbulence model is used; (3) the exponential coherence function proposed in Annex B of the IEC 1400-1 standard is used for the longitudinal component; and (4) the exponential coherence function proposed by the 'Engineering Science Data Unit' (ESDU) is used for the transversal component. Furthermore, it is highly recommended to base the load spectra on at least six realisations and to include the spatial wind speed variations in longitudinal direction when the turbine is yawed. 41 figs., 18 tabs., 20 refs.

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