Aeroelastic stability analysis of wind turbines using an eigenvalue approach

Abstract

AbstractA 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.