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Stability limits for a full wind turbine equipped with trailing edge systems. by Thomas Buhl, Mac Gaunaa, Leonardo Bergami and Peter B. Andersen. Outline. Motivation 2D stability 3D stability Results Conclusion. Motivation. Complex terrain CFD by Dr. Bechmann Risø. Siemens Wind power.
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Stability limits for a full wind turbine equipped with trailing edge systems by Thomas Buhl, Mac Gaunaa, Leonardo Bergami and Peter B. Andersen
Outline • Motivation • 2D stability • 3D stability • Results • Conclusion
Motivation Complex terrain CFD by Dr. Bechmann Risø Siemens Wind power
Adaptive trailing edges From 2003 to today: three large research projects involving more than 10 researchers, 6 master thesis and 3 Ph.d’s Inspiration Not applicable!
Controller ”aerodynamic” controller part ”elastic” controller part ”pitch” controller part ”power” controller part
Motivation Load reductiononUpwind turbine – by P. B. Andersen
2D stability 2D stability results from L. Bergami and M. Gaunaa
Full turbine stability Results -Original turbine with and without flaps
Moving the center of gravity Figures made by Li Na in ADAPWING2 projectfunded by Danish Research Council
2D Stability -Moving the center of gravity From: Hansen, M.H., Aeroelastic instability problems for wind turbines. Wind Energy (2007) 10 , 551-577
Full turbine stability Results -Moving the center of gravity
Full turbine stability Results -Moving the center of gravity
Conclusions • Results from 2D studies show that adding flap control generally lowers the stability limits • Results from 2D show that the effects of adding elastic trailing edges are not trivial. Possibility of drastically lowered flutter velocities. • The reference turbine is very stable. • The full turbine results show that the critical tip speed for which instability occurs is lower for turbines equipped with trailing edge flaps compared to the turbine without. • In most of the instability cases found an artificial propeller mode (large forward blade deflections) occurs.
Future work • Emergency stop • future extensions to this work should focused also on the controller parameters and the influence of these on the stability limits • Elastic flaps • Aggresivily tuned flap control • Less stable reference turbine • This work is partially funded by Acknowledgement