todd griffith - challenges and opportunities for large scale floating offshore vertical axis wind...
TRANSCRIPT
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
Challenges and Opportunities for Large-scale Floating Offshore
Vertical Axis Wind Turbines
D. Todd Griffith, PhD
Sandia National Laboratories 2016 Wind Turbine Blade Workshop
Albuquerque, NM August 31, 2016
Document Number: SAND2015-9794 PE
Characteristics of Offshore Wind
Opportunities Proximity to population centers Better winds Vast resource Scale-up opportunity
Challenges High LCOE High BOS costs Accessibility Inexperience, Immaturity
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Large reduction in Deepwater Offshore COE may require non-incremental system
solutions
Floating VAWTs
Available at www.sandia.gov/wind
Partners
Sandia Team: Roles and Responsibilities
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T. Griffith Project Coordinator System Design, Dynamics & Loads, Cost Analysis
B. Owens VAWT Codes & VAWT Design
D. Bull K. Ruehl Carlos Michelen B. Gunawan S. Bredin V. Neary
Floating Systems (platform and mooring) Met ocean conditions Wave characterization & analysis Hydrodynamics codes
B. Ennis K. Moore
VAWT aero-hydro-elastic simulations Modal Analysis Drivetrain Modeling
G. Bacelli Controls; Design Optimization; Dynamic Stability M. Barone VAWT Aerodynamics J. Paquette VAWT Structural Analysis
Sandia Wind Program: From 1970s to 1990s
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Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
Standards Applicable to Large-
scale Floating VAWTs
Standards and Load Cases
IEC 61400-3 addresses offshore wind design conditions Gust with Direction Change
VAWTS are less sensitive as tower clearance would not be an issue and they aren’t as affected by direction changes
Vertical Shear VAWTs are less sensitive to vertical wind shear as they
assimilate those changes along the height of the rotor. Extreme Gusts
VAWTs may be more impacted as the total blades solidity will likely be higher.
Cut-Out VAWTs will likely be much more sensitive to cut-out load cases
because of stall control
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Project Objectives
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Improve knowledge of the technical and economic feasibility of a floating offshore VAWT system.
The most critical barrier to offshore wind, high Cost of Energy (COE), is specifically targeted through a series of studies:
1. Technical Barriers & Standards 2. Rotor Design Studies 3. Platform and Mooring Design Studies 4. VAWT Design Codes 5. Innovations & Opportunities 6. LCOE Analysis
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
Rotor Design Studies
VAWT Structural Design Study
Reduction of parameter space was essential at the early stages of the design process: Architecture of the rotor Number of blades Chord length Material Blade tapering scheme
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Structural Design Study: Configurations
Parameter Values Considered
Architecture Darrieus, V
Number of Blades 2, 3
Tip Chord Length 2m, 3m
Composite Material: Glass/Epoxy, Carbon/Epoxy
Tapering Scheme (Darrieus only, V-VAWTS used Single Taper)
No Taper, Single Taper, Double Taper
Curvature or Power Law Exponent (V-VAWT)
n=1, n=3, n=5 0
20
40
60
80
100
120
140
160
180
0 20 40 60
Heig
ht (m
)
Radius (m)
DarrieusV, n=1V, n=2V, n=3V, n=4V, n=5
ANSYS Beam Models of D and V
VAWTS
D and V VAWT Shapes
Rotor Aero Design Population
24 Candidate Rotor Design External Shapes 12 Darrieus :
large/small chord single/double/no blade taper two/three blades
12 “V”-Rotors : large/small chord power law shape exponent = 1/3/5 two/three blades
Constraints Max radius = 54 m Same capture area NACA 0021 airfoil section
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VAWT Aerodynamic Design Analysis
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AEP
Platform
Fatigue
Power curves
Parked Loads
Operating Loads
1 2
3 4
XY
Z
X Y
Z
X
Y
Z
X
YZ
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JUL 13 201214:35:33
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DISPLACEMENT DISPLACEMENT
DISPLACEMENT DISPLACEMENT
STEP=1SUB =5FREQ=2.0265DMX =.021155
STEP=1SUB =5FREQ=2.0265DMX =.021155
STEP=1SUB =5FREQ=2.0265DMX =.021155
STEP=1SUB =5FREQ=2.0265DMX =.021155
CACTUS to OWENS Code Coupling Results
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Configuration Max Tower Top Disp.
(m)
Max Blade Total Disp.
(m)
% Tower Top Disp.
% Blade Disp. at
Mid-Span DC2LCDT 2.14 2.05 1.6 3.1 DC3LCDT 2.68 2.35 2.0 3.6 DG2LCDT 7.53 4.41 5.7 6.7 DG3LCDT 1.26 0.95 1.0 1.4 VC2N5LC 0.23 1.92 0.4 1.9 VC3N5LC 0.23 1.66 0.4 1.6
Ultimate strain allowable: 6000 micro-strain
Fatigue strain allowable: 3500 micro-strain
Displacements:
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
Platform & Mooring Design Studies
Platform Options Tailored solution to a floating VAWT
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Spar
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Semi-Submersible
Platform Sizing Study for Range of Topside Masses
Dynamic Loading on Platform is Important for VAWTs
RPM 2P (seconds) 4P (seconds)4 7.500 3.750
7.2 4.167 2.083
RPM 3P (seconds) 6P (seconds)4 5.000 2.500
6.3 3.175 1.587
Two sources: Wave and VAWT Dynamics VAWT periods: Due to oscillating VAWT loads (torque, pitch, and roll)
VAWT Periods for 2 and 3 bladed Darrieus machines:
The lower per rev is dominant.
3 bladed VAWT has lower period of primary loading (close to 3 seconds).
Comparison: Spar vs. Semisubmersible
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HAWT
VAWT (with equal mass of
600 mt)
VAWT (with mass of 973
mt) Spar-buoy
Semi-Sub
Spar-buoy
Semi-Sub
Spar-buoy
Semi-Sub
Topside Mass (mt) 600 600 600 600 973 973
Platform Steel Mass (mt) 2,000 2,900 1045 1708 1,500 2,370
Percent mass reduction versus HAWT
-- -- 48% 41% 25% 18%
Comparison of platform steel mass for two platform/floater types and two topside types of equal power rating (5MW)
1. Fowler, M., Bull, D., and Goupee, A.: A Comparison of Platform Options for Deep-water Floating Offshore Vertical Axis Wind Turbines: An Initial Study, Sandia National Laboratories Technical Report, SAND2014-16800, August 2014. 2. Griffith, D. T., Paquette, J., Barone, M., Goupee, A., Fowler, M., Bull, D., and Owens, B.: A study of rotor and platform design trade-offs for large-scale floating vertical axis wind turbines, Science of making torque from wind conference, Munich, Germany, 2016.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
VAWT Design Codes @ Sandia
Sandia VAWT Codes List
Geometry/Modeling & Post-processing VAWTGen Code
Aerodynamics CACTUS code
Structural Dynamics OWENS code Features: Modal, Transient, Static
Hydrodynamics WaveEC2Wire code Notes: Coupled with OWENS
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Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of
Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. 2012-5130P
Innovations and Analysis to Mitigate Barriers and Design Challenges
Summary of Investigated Topics
1. Novel VAWT Airfoils (TU-Delft) 2. Aero-elastic Stability Analysis 3. Rotor-Platform Coupled Dynamic Stability 4. Manufacturing (ISU/Sandia) 5. Balance of Station Cost Reduction 6. Storm Survival and Load Alleviation
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Is Aeroelastic Stability an issue for large-scale VAWTs?
0 5 10 15 20 25 30-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
Rotor Speed (RPM)
Dam
ping
Rat
io
DG2LCDTDG3LCDTDC2LCDTDC3LCDTVC2N5LCVC3N5LC
Owens B.C. and Griffith, D.T. “Aeroelastic Stability Investigations for Large-scale Vertical Axis Wind Turbines,” Science of Making Torque from Wind Conference, Copenhagen, Denmark, June 2014
5 MW Design Studies
Trend with Increasing Blade Length: Approaching Flutter Speed for Horizontal Axis Wind Turbines (HAWTs
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2015-9794 PE
Deep-water Offshore VAWT LCOE Analysis
System LCOE Trends: AEP, RPM, Rotor vs Platform
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Website and References (selected)
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http://www.sandia.gov/wind http://energy.sandia.gov/energy/renewable-energy/wind-power/offshore-wind/innovative-offshore-vertical-axis-wind-turbine-rotors/ Publications 1. Sutherland, H.J., Berg, D.E., and Ashwill, T.D., “A Retrospective of VAWT Technology,” Sandia National Laboratories
Technical Report, SAND2012-0304, January 2012. 2. Owens, B., Hurtado, J., Barone, M., and Paquette, J., “An Energy Preserving Time Integration Method for Gyric Systems:
Development of the Offshore Wind Energy Simulation Toolkit” Proceedings of the European Wind Energy Association Conference & Exhibition. Vienna, Austria, 2013.
3. Owens, B.C., Hurtado, J.E., Paquette, J., Griffith, D.T., and Barone, M., “Aeroelastic Modeling of Large Offshore Vertical-axis Wind Turbines: Development of the Offshore Wind Energy Simulation Toolkit,” 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, April 8–11, 2013, Boston, MA, USA, AIAA-2013-1552.
4. Owens, B.C., Griffith, D.T., and Hurtado, J.E., “Modal Dynamics and Stability of Large Multi-megawatt Deepwater Offshore Vertical-axis Wind Turbines: Initial Support Structure and Rotor Design Impact Studies,” 32nd ASME Wind Energy Symposium, National Harbor, MD, USA, January 2014.
5. Ragni, D., Simao-Ferreira, C., and Barone, M., “Experimental and Numerical Investigation of an Optimized Airfoil for Vertical Axis Wind Turbines,” 32nd ASME Wind Energy Symposium, National Harbor, MD, USA, January 2014.
6. Fowler, M.J., Owens, B.C., Goupee, A.J., Hurtado, J.E., Griffith, D.T., and Alves, M., “Hydrodynamic Module Coupling in the Offshore Wind Energy Simulation (OWENS) Toolkit,” Proceedings of the 33rd ASME International Conference on Ocean, Offshore and Arctic Engineering (OMAE2014), June 8–13, 2014, San Francisco, California, USA, Paper OMAE2014-24175.
7. Owens, B.C., and Griffith, D.T., “Aeroelastic Stability Investigations of Large-scale Vertical Axis Wind Turbines,” Journal of Physics Conference Series, Science of Making Torque from Wind Conference, June 18–20, 2014, Lyngby, Denmark.
8. Fowler, M., Bull, D., and Goupee, A, “A Comparison of Platform Options for Deep-water Floating Offshore Vertical Axis Wind Turbines: An Initial Study,” Sandia National Laboratories Technical Report, SAND2014-16800, August 2014.
9. Griffith, D. T., Paquette, J., Barone, M., Goupee, A., Fowler, M., Bull, D., and Owens, B.: A study of rotor and platform design trade-offs for large-scale floating vertical axis wind turbines, Science of making torque from wind conference, Munich, Germany, 2016.
High-resolution Offshore Wind Farm Modeling
Offshore Wind @ Sandia
Deepwater Offshore
VAWT
Offshore Siting Analysis
Large Offshore Rotors
Sensing, Structural Health, and Prognostics
• Vision: Promote & accelerate the commercial OW industry and reduce costs through technical innovation:
• Siting/Permitting: Sediment Transport & Radar • Large offshore HAWT rotors • Deepwater VAWT system • Structural health and prognostics management • Offshore wind farm modeling