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Aeroelastic stability analysis of wind turbines using an eigenvalue approach

Authors

  • M. H. Hansen

    Corresponding author
    1. Wind Energy Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark
    • M. H. Hansen, Wind Energy Department, Risø National Laboratory, PO Box 49, Dk-4000 Roskilde, Denmark
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Abstract

A design tool for performing aeroelastic stability analysis of wind turbines is presented in this paper. The method behind this tool is described in a general form, as independent of the particular aeroelastic modelling as possible. Here, the structure is modelled by a Finite beam Element Method, and the aerodynamic loads are modelled by the Blade Element Momentum method coupled with a Beddoes-Leishman type dynamic stall model in a state-space formulation. The linearization of the equations of motion is performed about a steady-state equilibrium, where the deterministic forcing of the turbine is neglected. To eliminate the periodic coefficients and avoid using the Floquet Theory, the multi-blade transformation is utilized. From the corresponding eigenvalue problem, the eigenvalues and eigenvectors can be computed at any operation condition to give the aeroelastic modal properties: Natural frequencies, damping and mode shapes. An example shows a good agreement between predicted and measured aeroelastic damping of a stall-regulated 600 kW turbine. Copyright © 2004 John Wiley & Sons, Ltd.

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