Abstract
The presented study concerns experimental dynamic identification of (slightly) anisotropic bladed rotors under operating conditions. Since systems with a rotating rotor do not fall into a category of time invariant system, a straightforward application of modal analysis is not valid. Under assumptions of linearity and constant angular speed, a system with rotating rotor can be considered as a linear periodically time variant (LPTV) system; dynamic identification of such systems require dedicated methods. The Harmonic OMA Time Domain (H-OMA-TD) method is one of very few techniques able to deal with anisotropic rotors. This study demonstrates the method on a simple six degrees-of-freedom mechanical system with a three-bladed rotor. It shows that the method is capable of identifying the phenomena specific for anisotropic rotors. The technique is compared with another technique, multiblade coordinate (MBC) transformation, and the advantages of H-OMA-TD become apparent when the rotor is anisotropic. Finally, the method is demonstrated on data measured on a real Vestas V27 wind turbine and data obtain via HAWC2 simulations of the same wind turbine.
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Notes
- 1.
Comparing Fig. 14.9 with Figs. 14.6 and 14.7, one has to take into account the scaling between the rotational and translational DOFs: in the analytical and simulation cases, the rotational DOFs are in angular units. In the case of measured data, the rotational DOFs are in translational units (here, the acceleration measured in the tangential direction at the tip of the blades).
References
Tcherniak, D., Chauhan, S., Rossetti, M., Font, I., Basurko, J., Salgado, O.: Output-only modal analysis on operating wind turbines: application to simulated data. In: European Wind Energy Conference, Warsaw, Poland (2010)
Jhinaoui, A., Mevel, L., Morlier, J.: A new SSI algorithm for LPTV systems: application to a hinged-bladed helicopter. Mech. Syst. Signal Process. 42(1), 152–166 (2014)
Allen, M.S., Sracic, M.W., Chauhan, S., Hansen, M.H.: Output-only modal analysis of linear time-periodic systems with application to wind turbine simulation data. Mech. Syst. Signal Process. 25, 1174–1191 (2011)
Requesón, O.R., Tcherniak, D., Larsen, G.C.: Comparative study of OMA applied to experimental and simulated data from an operating Vestas V27 wind turbine. In: Operational Modal Analysis Conference (IOMAC), Gijón, Spain (2015)
Mevel, L., Gueguen, I., Tcherniak, D.: LPTV subspace analysis of wind turbine data. In: European Workshop on Structural Health Monitoring (EWSHM), Nantes, France (2014)
Allen, M.S.: Frequency-domain identification of linear time-periodic systems using LTI techniques. J. Comput. Nonlinear Dyn. 4(4) (2009)
Yang, S., Tcherniak, D., Allen, M.S.: Modal analysis of rotating wind turbine using multi-blade coordinate transformation and harmonic power spectrum. In: Int. Modal Analysis Conference (IMAC), Orlando (2014)
Tcherniak, D., Yang, S., Allen, M.S.: Experimental characterization of operating bladed rotor using harmonic power spectra and stochastic subspace identification. In: International Conference on Noise and Vibration Engineering (ISMA), Leuven, Belgium (2014)
Tcherniak, D., Allen, M.S.: Experimental characterization of an operating Vestas V27 wind turbine using harmonic power spectra and OMA SSI. In: International Operational Modal Analysis Conference (IOMAC), Gijón, Spain (2015)
Ewins, D.J.: Modal Testing, Theory, Practice, and Application. Research Study Press, Baldock (2000)
Skjoldan, P.F.: Aeroelastic modal dynamics of wind turbines including anisotropic effects. PhD dissertation, Roskilde, Denmark (2011)
Hansen, M.H.: Improved modal dynamics of wind turbines to avoid stall-induced vibrations. Wind Energy 6, 179–195 (2003)
Hansen, M.H.: Aeroelastic stability analysis of wind turbines using eigenvalue approach. Wind Energy 7, 133–143 (2004)
Xie, W.-C.: Dynamic Stability of Structures. Cambridge University Press, New York (2006)
Wereley, N.M.: Analysis and control of linear periodically time varying systems. PhD dissertation, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge (1991)
Tcherniak, D.: Rotor anisotropy as a blade damage indicator for wind turbine structural health monitoring systems. Mech. Syst. Signal Process. (Accepted for publication) (2015)
Tcherniak, D., Chauhan, S., Hansen, M.H.: Applicability limits of operational modal analysis to operational wind turbines. In: International Modal Analysis Conference (IMAC), Orlando (2010)
Larsen, T.J., Hansen, A.M.: How 2 HAWC2, the User’s Manual. Technical University of Denmark, Lyngby (2013)
Tcherniak, D., Larsen, G.C.: Application of OMA to an operating wind turbine: now including vibration data from the blade. In: International Operational Modal Analysis Conference (IOMAC), Guimarães, Portugal (2013)
Acknowledgement
The work was partly supported by EUDP (Danish Energy Technology Development and Demonstration Programme), grant number 64011-0084 “Predictive Structure Health monitoring of Wind Turbines”. The authors wish to acknowledge the great help from Óscar Ramírez Requesón for performing the HAWC2 simulations of the Vestas V27 wind turbine.
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Tcherniak, D., Allen, M.S. (2016). Experimental Dynamic Characterization of Operating Wind Turbines with Anisotropic Rotor. In: Pakzad, S., Juan, C. (eds) Dynamics of Civil Structures, Volume 2. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-29751-4_14
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