Eigen frequencies of a vertical axis wind turbine tower made out of laminated wood which are both bolted to the ground and supported by guy wires are studied and compared. Using beam theory, an analytical model taking the guy wires into account for calculating the first mode eigen frequency of the tower has been derived. The analytical model is then evaluated by comparing with FEM-simulations and measurements performed on the actual tower. The model is found to be reasonably accurate keeping in mind that the estimated masses and second moments of area are somewhat rough. Furthermore the model can be used to give an indication of the magnitude of change in eigen frequency when modifying a tower or guy wire property.
References
1.
ErikssonS.BernhoffH.LeijonM., “Evaluation of different turbine concepts for wind power,”Renewable and Sustainable Energy Reviews, vol. 12, pp. 1419–1434, ISSN 1364-0321, 2008.
2.
OttermoF.BernhoffH., “Resonances and Aerodynamic Damping of a Vertical Axis Wind Turbine,”Wind Engineering, vol. 36, no. 3, pp. 297–304, ISSN: 0309–524X, 2012.
DarrieusG. J. M., “Turbine having its rotating shaft transverse to the flow of the current”. US Patent 1.835.018, December 1931.
5.
KjellinJ., Vertical Axis Wind Turbines: Electrical System and Experimental Results, Ph.D. thesisUppsala University: ISBN: 978-91-554-8496-5, 2012.
6.
ErikssonS.BernhoffH.LeijonM., “A 225 kW Direct Driven PM Generator Adapted to a Vertical Axis Wind Turbine,”Advances in Power Electronics, vol. 2011, Article ID 239061, 2011.
7.
ErikssonS.KjellinJ.BernhoffH., “Tip Speed ratio control of a 200 kW VAWT with synchronous generator and variable DC-voltage,”Energy Science and Engineering, 2013: 1(3): 135–143.
8.
T. GMBH, “Wind Power Plant. Patent for Wooden Wind Turbine Tower”. Patent Pub. No: WO/2008/095667, International Application No: PCT/EP2008/000856.
9.
ErikssonS.BernhoffH.LeijonM., “Generator-Damped Torsional Vibrations of a Vertical Axis Wind Turbine,”Wind Engineering, 29(5): 449–461, 2005.
10.
BeerF. P., Vector mechanics for engineers: Statics and dynamics, ISBN 978-00-73-21222-7: McGraw-Hill, 2006.
11.
D'AmbrosioM.MedagliaM., “Vertical Axis Wind Turbines: History, Technology and Applications,”Master Thesis, Halmstad University, May 2010.
