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ISRN Renewable Energy
Volume 2012 (2012), Article ID 904269, 5 pages
http://dx.doi.org/10.5402/2012/904269
Research Article

Parking Strategies for Vertical Axis Wind Turbines

1Division for Electricity, Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21 Uppsala, Sweden
2Swedish Centre for Renewable Electric Energy Conversion, Uppsala University, P.O. Box 534, 751 21 Uppsala, Sweden

Received 20 September 2012; Accepted 18 October 2012

Academic Editors: S. S. Kalligeros, S. Li, and P. Lund

Copyright © 2012 F. Ottermo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Strategies for parking a vertical axis wind turbine at storm load are considered. It is proposed that if a directly driven permanent magnet synchronous generator is used, an elegant choice is to short-circuit the generator at storm, since this makes the turbine efficiently damped. Nondamped braking is found to be especially problematic for the case of two blades where torsional oscillations may imply thrust force oscillations within a range of frequencies.