Chapter33 Artificial and Natural Excitation Testing of SWiFT Vestas V27 Wind Turbines Timothy Marinone, David Cloutier, Bruce LeBlanc, Thomas Carne, and Palle Andersen Abstract The Scaled Wind Farm Technology facility has been developed by Sandia National Laboratories to enable rapid, cost-efficient testing and development of transformative wind energy technology. As part of this effort, ATA Engineering was contracted by Sandia to perform modal testing on multiple fully assembled wind turbines to gain a better understanding of the structures. This paper presents the results obtained from experimental modal analysis and operational modal analysis performed on Vestas V27 wind turbines recently installed at the Scaled Wind Farm Technology facility. Experimental modal results are compared between two identical wind turbines, identifying variability in both components and boundary conditions. Additionally, operational modal analysis was used on a single parked wind turbine under natural wind excitation. The operational modal results compare well to the results obtained from a conventional impact modal survey, providing promising results for future testing on larger turbines where measured external excitation may not be feasible. Keywords Wind turbines • Operational modal analysis • Stochastic subspace identification • Experimental modal characterization • Modal parameter estimation 33.1 Introduction Sandia National Laboratories (SNL) is developing the Scaled Wind Farm Technology (SWiFT) facility to enable rapid, costefficient testing and development of transformative wind energy technology. The site is intended to study complex turbine wake interactions and focus on damage mitigation, improved power performance, and recommended future site layouts. Since this site is designed to be open source and to provide data to all interested parties, the models must be accurate enough to be used for the desired analyses while preserving Vestas’ proprietary information. For this paper, two Vestas V27 (V27) wind turbines installed on site were tested to obtain modal properties for the validation of analysis models. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract DE-AC04-94AL85000. T. Marinone • D. Cloutier ( ) ATA Engineering, San Diego, CA 92130, USA e-mail: dave.cloutier@ata-e.com B. LeBlanc Sandia National Laboratories, Albuquerque, NM 87185, USA T. Carne MannaTech Engineering, Bozeman, MT 59715, USA P. Andersen Structural Vibration Solutions A/S, Aalborg East, Denmark M. Allen et al. (eds.), Dynamics of Coupled Structures, Volume 1: Proceedings of the 32nd IMAC, A Conference and Exposition on Structural Dynamics, 2014, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-04501-6__33, © The Society for Experimental Mechanics, Inc. 2014 343
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