Journal article
Implicit Floquet Analysis of Wind Turbines using Tangent Matrices of a Nonlinear Aeroelastic Code : Implicit Floquet analysis using tangent matrices of a non-linear code
Aeroelastic Design, Wind Energy Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark1
Wind Energy Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark2
Risø National Laboratory for Sustainable Energy, Technical University of Denmark3
The aeroelastic code BHawC for calculation of the dynamic response of a wind turbine uses a non‐linear finite element formulation. Most wind turbine stability tools for calculation of the aeroelastic modes are, however, based on separate linearized models. This paper presents an approach to modal analysis where the linear structural model is extracted directly from BHawC using the tangent system matrices when the turbine is in a steady state.
A purely structural modal analysis of the periodic system for an isotropic rotor operating at a stationary steady state was performed by eigenvalue analysis after describing the rotor degrees of freedom in the inertial frame with the Coleman transformation. For general anisotropic systems, implicit Floquet analysis, which is less computationally intensive than classical Floquet analysis, was used to extract the least damped modes.
Both methods were applied to a model of a three‐bladed 2.3 MW Siemens wind turbine model. Frequencies matched individually and with a modal identification on time simulations with the non‐linear model. The implicit Floquet analysis performed for an anisotropic system in a periodic steady state showed that the response of a single mode contains multiple harmonic components differing in frequency by the rotor speed.
Copyright © 2011 John Wiley & Sons, Ltd.
Language: | English |
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Publisher: | John Wiley & Sons, Ltd |
Year: | 2012 |
Pages: | 275-287 |
ISSN: | 10991824 and 10954244 |
Types: | Journal article |
DOI: | 10.1002/we.467 |
ORCIDs: | Hansen, Morten Hartvig |