Rational calibration of four IEC 61400-1 extreme external conditions

Authors

  • Gunner Chr. Larsen,

    Corresponding author
    1. Wind Energy Department, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde, Denmark
    • Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvel 399, PO Box 49, DK 4000 Roskilde, Denmark
    Search for more papers by this author
  • Kurt S. Hansen

    1. Department of Mechanical Engineering, Fluid Mechanics, Nils Koppels Allé, DTU-Building 403, Technical University of Denmark, Lyngby, Denmark
    Search for more papers by this author

Abstract

Based on a set of asymptotic statistical models on closed form this paper presents a rational and consistent calibration of four extreme external conditions defined in the International Electrotechnical Commission (IEC) 61400-1 standard: extreme operating gust, extreme wind shear, extreme coherent gust with direction change and extreme wind direction change. These four extreme external conditions are used in the definition of six of the IEC 61400-1 ultimate load cases. The statistical models are based on simple and easily accessible mean wind speed and turbulence characteristics of the atmospheric boundary layer. Using the wind climate characteristics prescribed in the IEC 61400-1 standard as input to the set of statistical models ensures consistency between the specified wind climate and the proposed extreme gust magnitudes. Differences and equalities between the present IEC specifications and proposed specifications of the magnitudes of the extreme external wind conditions are highlighted and discussed using an illustrative example based on two selected terrain types. Copyright © 2008 John Wiley & Sons, Ltd.

Ancillary