Abstract
Vertical axis wind turbines (VAWTs) are advantageous for the development of large-scale offshore wind power because the drive system is located at the bottom of the turbine. This study investigates the structural strength of a tri-floater floating foundation supporting a 2.6 MW Darrieus VAWT. Finite element models of the floating foundation were developed using space plate-beam elements. The environmental loads, such as the aerodynamic loads, static wind loads, and wave-current loads, were considered. The general strengths of the floating foundation were calculated for the normal operating case (a cut-out wind speed of 25 m s−1 and blade rotation of 12 r min−1 were used to analyze the most unfavorable loads) and an extreme case (wind speed of 40 m s−1 and parked blades), and the weak components of the structure were analyzed. The results show that the floating foundation meets the strength requirements and the structural stress is highest when the wave, wind, and current are in a collinear direction. The main and secondary supporting bars transmit the loads between the stand columns and the tower foundation, and their stresses are higher than those in the other components. In the actual design, these supporting bars should be strengthened. The aerodynamic loads are very important and should be considered in the structural strength analysis of the floating foundation and the floating wind turbine system.
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References
API RP-2SK, 2005. Design and Analysis of Station Keeping Systems for Floating Structures. American Petroleum Institute, Washington, DC, 190pp.
Berg, D. E., 1983. An improved double-multiple stream tube model for the Darrieus type vertical-axis wind turbine. In: Proceedings of the Sixth Biennial Wind Energy Conference and Workshop. Minneapolis, MN, 75–85.
Blusseau, P., and Patel, M. H., 2012. Gyroscopic effects on a large vertical axis wind turbine mounted on a floating structure. Renewable Energy, 46: 31–42, DOI: 10.1016/j.renene.2012.02.023.
Borg, M., Shires, A., and Collu, M., 2014. Offshore floating vertical axis wind turbines, dynamics modelling state of the art. Part I: Aerodynamics. Renewable and Sustainable Energy Reviews, 39: 1214–1225, DOI: 10.1016/j.rser.2014.07.096.
Cahay, M., Luquiau, E., Smadja, C., and Silvert, F., 2011. Use of a vertical wind turbine in an offshore floating wind farm. Journal of Petroleum Technology, 63 (7): 105–107.
China Classification Society, 2005. Rules for Construction and Classification of Mobile Offshore Drilling Units. China Communications Press, Beijing, 453pp.
Collu, M., Borg, M., Shires, A., Rizzo, F. N., and Lupi, E., 2014. FLOVAWT: Further progresses on the development of a coupled model of dynamics for floating offshore VAWTS. In: Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. San Francisco, California, 9: V09BT09A044.
Det Norske Veritas (DNV), 2004. Structural Design of Column Stabilised Units (LRFD Method). Oslo, Norway, 33pp.
Det Norske Veritas (DNV), 2013. Design of Floating Wind Turbine Structures. DNV-OS-J103, Oslo, Norway, 129pp.
Faltinsen, O., 1998. Sea Loads on Ships and Offshore Structures. Cambridge University Press, Cambridge, 340pp.
Hu, Z. Q., Liu, Y., and Wang, J., 2016. An integrated structural strength analysis method for spar type floating wind turbine. China Ocean Engineering, 30 (2): 217–230, DOI: 10.1007/s13344-016-0013-y.
IEC61400-3, 2009. Wind Turbines, Part 3: Design Requirements for Off-Shore Wind Turbines. International Electrochemical Commission, Geneva, 268pp.
Kvittem, M. I., and Moan, T., 2015. Frequency versus time domain fatigue analysis of a semisubmersible wind turbine tower. Journal of Offshore Mechanics & Arctic Engineering, 137: 011901–1.
Lefebvre, S., and Collu, M., 2012. Preliminary design of a floating support structure for a 5 MW offshore wind turbine. Ocean Engineering, 40: 15–26, DOI: 10.1016/j.oceaneng.2011.12.009.
Liu, L. Q., Guo, Y., and Zhao, H. X., 2017. Motions of a 5 MW floating VAWT evaluated by numerical simulations and model test. Ocean Engineering, 144: 21–34.
Ma, T., Wang, F., Cai, Q., Yang, Y., and Peng, X. B., 2011. Application of inertia relief in reusable launch vehicle structure strength analysis. In: 62nd International Astronautical Congress. Cape Town, 7: 5921–5925.
Owens, B., and Griffithy, D., 2014. Modal dynamics and stability of large multi-megawatt deepwater offshore vertical-axis wind turbines: Initial support structure and rotor design impact studies. In: 32nd ASME Wind Energy Symposium. Maryland, 1–21.
Paravischivoiu, I., 2002. Wind Turbine Design with Emphasis on Darrieus Concept. Polytechnic International Press, Montreal, 352pp.
Ramtin, R., Paul, F., and Philippe, D., 2018. Fatigue life sensitivity of monopile-supported offshore wind turbines to damping. Renewable Energy, 123: 450–459.
Tang, Y. G., Hu, J., and Liu, L. Q., 2011. Study on the dynamic response for floating foundation of offshore wind turbine. In: Proceedings of the ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. Rotterdam, 929–933.
Vita, L., 2011. Offshore floating vertical axis wind turbines with rotating platform. PhD thesis. Danish Technical University, Denmark.
Wang, K., Luan, C., Moan, T., and Hansen, M. O. L., 2014. Comparative study of a FVAWT and a FHAWT with a semisubmersible floater. In: Proceedings of the 24th International Ocean and Polar Engineering Conference. Busan, 302–310.
Willy, T., Tjukup, M., and Sohif, M., 2015. Darrieus vertical axis wind turbine for power generation II: Challenges in HAWT and the opportunity of multi-megawatt Darrieus VAWT development. Renewable Energy, 75: 560–571, DOI: 10.1016/j.renene.2014.10.039.
Zhang, X. R., Liu, L. Q., Wang, F. D., and Tang, Y. G., 2017. Study on the aerodynamic characteristics of offshore floating vertical axis wind turbine. Journal of Harbin Engineering University, 38 (6): 859–865, DOI: 10.11990/jheu.201603083 (in Chinese with English abstract).
Acknowledgements
This project was supported by the National Natural Science Foundation of China (No. 51579176), the Natural Science Foundation of Tianjin (No. 16JCYBJC21200), and the Research Fund of the State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University (No. 1501).
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Liu, L., Zhao, H., Xu, W. et al. Structural Strength Analysis of a Tri-Floater Floating Foundation for Offshore VAWT. J. Ocean Univ. China 17, 753–762 (2018). https://doi.org/10.1007/s11802-018-3434-9
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DOI: https://doi.org/10.1007/s11802-018-3434-9