An extreme loading study has been conducted comprising a general wind climate analysis as well as a wind turbine reliability study. In the wind climate analysis, the distribution of the (horizontal) turbulence standard deviation, conditioned on the meanwind speed, has been approximated by fitting a three parameter Weibull distribution to the measured on-shore and off-shore data for wind speed variations. Specific recommendations on off-shore design turbulence intensities are lacking in the presentIEC-code. Based on the present analysis of the off-shore wind climate on two shallow water sites, a design turbulence intensity for off-shore application is proposed which, in the IEC code framework, is applicable for extreme as well as for fatigue loaddetermination. In order to establish a rational method to analyse wind turbine components with respect to failure in ultimate loading, and in addition to establish partial safety factors for design of such components against this failure mode, structuralreliability methods must be applied. This type of analysis accounts for the variability of the external (wind) loading (as addressed in the analyses of the general wind climate) - and thereby the induced variability in the component stress response - aswell as variability in material resistance. The present study comprises the development of a procedure suitable for dealing with this type of analyses. The main effort has been put on the methodology. Application of the procedure is illustrated byapplication to the event of failure in ultimate loading in flapwise bending in the normal operating condition of a site-specific turbine.
Vindenergi og atmosfæriske processer; Risø-R-1111; Risø-R-1111(EN)