Reducing the loads experienced by wind turbine rotor blades can lower the cost of energy of wind turbines. “Smart rotor control” concepts have emerged as a solution to reduce fatigue loads on wind turbines. In this approach, aerodynamic load control devices are distributed along the span of the blade, and through a combination of sensing, control, and actuation, these devices dynamically control the blade loads. While smart rotor control approaches are primarily focused on fatigue load reductions, extreme loads on the blades may also be critical in determining the lifetime of components, and the ability to reduce these loads as well would be a welcome property of any smart rotor control approach. This research investigates the extreme load reduction potential of smart rotor control devices, namely, trailing edge flaps, in the operation of a 5 MW wind turbine. The controller utilized in these simulations is designed explicitly for fatigue load reductions; nevertheless its effectiveness during extreme loads is assessed. Simple step functions in the wind are used to approximate gusts and investigate the performance of two load reduction methods: individual flap control and individual pitch control. Both local and global gusts are simulated. The results yield important insight into the control approach that is utilized, and also into the differences between using individual pitch control and trailing edge flaps for extreme load reductions. Finally, the limitation of the assumption of quasisteady aerodynamic behavior is assessed.

1.
Lackner
,
M.
, and
van Kuik
,
G.
, 2009, “
A Comparison of Smart Rotor Control Approaches Using Trailing Edge Flaps and Individual Pitch Control
,”
47th AIAA Aerospace Science Meeting and Exhibit
.
2.
Barlas
,
T.
, 2006, “
Smart Rotor Blades and Rotor Control for Wind Turbines: State of the Art
,” knowledge base report for upwind wp 1b3, Delft University Wind Energy Research Institute (DUWIND), Report No. UpWind WP 1B3.
3.
Barlas
,
T.
, and
van Kuik
,
G.
, 2007, “
State of the Art and Prospectives of Smart Rotor Control for Wind Turbines
,”
J. Phys.: Conf. Ser.
1742-6588,
75
, p.
012080
.
4.
van Engelen
,
T.
, and
van def Hooft
,
E.
, 2005, “
Individual Pitch Control Inventory
,” Technical University of Delft, Technical Report No. ECN-C–03-138.
5.
Bossanyi
,
E.
, 2003, “
Individual Blade Pitch Control for Load Reduction
,”
Wind Energy
1095-4244,
6
, pp.
119
128
.
6.
Selvam
,
K.
, 2007, “
Individual Pitch Control for Large Scale Wind Turbine
,” MS thesis, Technical University of Delft, Delft, The Netherlands.
7.
Andersen
,
P.
,
Henriksen
,
L.
,
Gaunaa
,
M.
,
Bak
,
C.
, and
Buhl
,
T.
, 2008, “
Integrating Deformable Trailing Edge Geometry in Modern Mega-Watt Wind Turbine Controllers
,”
2008 European Wind Energy Conference and Exhibition
.
8.
McCoy
,
T.
, and
Griffin
,
D.
, 2006, “
Active Control of Rotor Aerodynamics and Geometry: Statues, Methods, and Preliminary Results
,”
44th AIAA Aerospace Science Meeting and Exhibit
.
9.
Lackner
,
M.
, and
van Kuik
,
G.
, 2009, “
A Comparison of Smart Rotor Control Approaches Using Trailing Edge Flaps and Individual Pitch Control
,”
Wind Energy
1095-4244, to be published.
10.
Zayas
,
J.
,
van Dam
,
C.
,
Chow
,
R.
,
Baker
,
J.
, and
Mayda
,
E.
, 2006, “
Active Aerodynamics Load Control for Wind Turbine Blades
,”
European Wind Energy Conference
.
11.
Bossayni
,
E.
, 2003, GH BLADED Version 3.80 Theory Manual, Garrad Hassan and Partners.
12.
Bossayni
,
E.
, 2004, GH BLADED Version 3.80 User Manual, Garrad Hassan and Partners.
13.
Jonkman
,
J.
,
Butterfield
,
S.
,
Musial
,
W.
, and
Scott
,
G.
, 2008, “
Definition of a 5-MW Reference Wind Turbine for Offshore System Development
,” National Renewable Energy Laboratory Report No. TP 500-38060.
14.
Troldborg
,
N.
, 2005, “
Computational Study of the Risøb1-18 Airfoil With a Hinged Flap Providing Variable Trailing Edge Geometry
,”
Wind Eng.
0309-524X,
29
(
2
), pp.
89
113
.
15.
Drela
,
M.
, and
Youngren
,
H.
, 2001, XFOIL 6.9 User Primer, MIT.
16.
Bir
,
G.
, 2008, “
Multi-Blade Coordinate Transformation and Its Application to Wind Turbine Analysis
,”
46th AIAA Aerospace Science Meeting and Exhibit
.
17.
Coleman
,
R.
, and
Feingold
,
A.
, 1958, “
Theory of Self-Excited Mechanical Oscillations of Helicopter Rotors With Hinged Blades
,” NASA, Technical Report No. 1351.
18.
Bossayni
,
E.
, 2004, “
Developments in Individual Pitch Control
,”
EWEA Special Topic Conference: The Science of Making Torque From Wind
.
19.
Leishman
,
J.
, 2006,
Principles of Helicopter Aerodynamics
,
Cambridge University Press
,
Cambridge
.
20.
Gaunaa
,
M.
, 2005, “
Unsteady 2D Potential-Flow Forces on a Variable Geometry Airfoil Undergoing Arbitrary Motion
,” Risoe, Technical Report No. R-1478(EN).
21.
Hansen
,
M.
,
Gaunaa
,
M.
, and
Madsen
,
H.
, 2004, “
A Beddoes-Leishman Type Dynamic Stall Model in State-Space and Indicial Formulations
,” Risoe, Technical Report No. R-1354(EN).
22.
Andersen
,
P.
,
Gaunaa
,
M.
,
Bak
,
C.
, and
Buhl
,
T.
, 2006, “
Load Alleviation on Wind Turbine Blades Using Variable Airfoil Geometry
,”
2006 European Wind Energy Conference and Exhibition
.
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