Stability limits for a full wind turbine equipped with trailing edge systems

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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

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Outline

• Motivation
• 2D stability
• 3D stability
• Results
• Conclusion

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Motivation
Complex terrain CFD by Dr. Bechmann Risø
Siemens Wind power
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Motivation
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Adaptive trailing edges
From 2003 to today three large research
projects involving more than 10 researchers, 6
master thesis and 3 Ph.ds
Inspiration
Not applicable!
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Typical turbine layout
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Controller
aerodynamic controller part
elastic controller part
pitch controller part
power controller part
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Motivation
Load reduction on Upwind turbine by P. B.
Andersen
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Wind tunnel results
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2D stability
2D stability results from L. Bergami and M. Gaunaa
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Full turbine stability Results -Original turbine
no flaps
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Full turbine stability Results -Original turbine
with and without flaps
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Moving the center of gravity
Figures made by Li Na in ADAPWING2 project funded
by Danish Research Council
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Moving the center of gravity
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2D Stability -Moving the center of gravity
From Hansen, M.H., Aeroelastic instability
problems for wind turbines. Wind Energy (2007)
10 , 551-577
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Moving the center of mass
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Full turbine stability Results -Moving the
center of gravity
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Full turbine stability Results -Moving the
center of gravity
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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.

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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