1. Asa Sproul
MSEE Defense
April 3rd, 2015
Advisory Committee:
Duane C. Hanselman, Associate Professor of Electrical and Computer Engineering, Advisor
Bruce E. Segee, Professor of Electrical and Computer Engineering
Nathan D. Weise , Assistant Professor of Electrical and Computer Engineering at Marquette University

2. • Introduction
• Theory
• Testing
• Discussion
• Conclusion
Content
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3. April 3rd, 2015 Asa Sproul 3

4. • Ocean wave energy is highly underutilized
• 15-20x more available energy/m2 than wind or solar
• Estimated 8000-80,000 TWh/yr available throughout ocean
• Economical viability for capture not yet achieved
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Background

5. • WEC: Wave Energy Converter
• Mechanical structures absorb wave power
• Power capturing structure coupled with generator
• Maximum capture through mechanical resonance
• Can operate in various water depths
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What is a WEC?

6. • LIMPET:
• Pelamis:
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Technology Under Development

7. • Wave Dragon:
• PowerBuoy:
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Technology Under Development con’t

8. • No universal design converged upon
• Find viable control method of novel prototype
• Maximize mechanical efficiency
• Provide groundwork for large-scale device
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Research Purpose

9. April 3rd, 2015 Asa Sproul 9

10. • 𝐹 = 𝑚𝑥 + 𝑅𝑥 + 𝑆𝑥
• Can be compared with power
absorbing structure of WEC
• Provides basis for control
• 𝐹 = 𝐹𝑤𝑎𝑣𝑒
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Linearized Wave Equation

11. • 𝐹𝑔𝑒𝑛 = 𝑚 𝑔𝑒𝑛 𝑥 + 𝑅 𝑔𝑒𝑛 𝑥 + 𝑆 𝑔𝑒𝑛 𝑥
• 𝐹𝑔𝑒𝑛 ∝ 𝑇𝑔𝑒𝑛 ∝ 𝐼𝑔𝑒𝑛
• Current controller may be used
• Controller input based on acceleration, speed, and position
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Assisted Movement

12. April 3rd, 2015 Asa Sproul 12
Simplified Control Diagram

13. April 3rd, 2015 Asa Sproul 13
RTI F2

14. • Typically expressed as available power per meter crest length
• 𝑃 𝑤𝑎𝑣𝑒,𝑚𝑐𝑙 =
1
8
𝜌𝑔𝐻2 𝑐 𝑔
• Equation takes 3 forms
1. Shallow
2. Intermediate
3. Deep
• Equation form depends on water depth and wavelength
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Wave Power
𝜌 = mass density of liquid
𝑔 = acceleration due to gravity
𝐻 = peak-to-trough wave height
𝑐 𝑔 = wave’s group velocity

15. • Means of measuring efficiency and economic viability
• Defined as “The width of the wavefront (assuming uni-
directional waves) that contain the same amount of power as
that absorbed by the WEC.” Price et al., 2009
• 𝐶𝑊 =
𝑃 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑
𝑃 𝑤𝑎𝑣𝑒,𝑚𝑐𝑙
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Capture Width

16. April 3rd, 2015 Asa Sproul 16

17. • 120’ long, 12’ wide, 8’ deep
• Programmable wave maker
• Wave Staff
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UNH Chase Laboratory Wave Tank

18. • Mounted frame
• Vessel facing
wave maker
• Wave attenuator
at far end
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Device Setup

19. • Motor/generator
• Brushed DC
• Coupled with gearbox
• Controlled from control
platform
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Power Take Off

20. • CUSP Educational Lab Inverter
• MATLAB, Simulink, dSPACE
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Hardware and Software

21. • Determine optimal control technique
• Validate wave front parallel configuration
• Operate device as intended for structural considerations
• Analyze system losses
• Provide groundwork for ongoing development
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Objectives

22. • Wave height and wave period
• Control methods
– Damping control
– Damping + inertial control
• Added mass
• Plate angle
• Frictional correction
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Test Variables

23. • 𝑃1 = 𝐼𝑉
• 𝑃2 = 𝑃1 + 𝐼2 𝑅
• 𝑃3 = 𝑃2 + 𝐵𝜔2
• 𝑃4 = 𝑃3 + 𝑇𝑠𝑡𝑖𝑐
• 𝑃5 =
𝑃4
0.93
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Capture Widths and System Losses
𝐶𝑊1−5 =
𝑃1−5
𝑃 𝑤𝑎𝑣𝑒,𝑚𝑐𝑙

24. April 3rd, 2015 Asa Sproul 24
Capture Widths and System Losses con’t
≈ 0.38
Not enough
torque

25. April 3rd, 2015 Asa Sproul 25

26. • Stationary frame will be floating at full scale
• Capture width needs further improvement
• Prototype should be optimized to panchromatic conditions
• Other control strategies should be tested
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Things to Consider

27. • Direct drive would eliminate frictional losses due to gearbox
• Generator optimized for low speed
• Generator optimized for high torque
• Brushless DC would provide better efficiency than brushed
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Power Take Off Improvements

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Trending

29. • Prototype to full scale parameter estimates
• Froude scale factor = 11
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Froude Scaling
Parameter Prototype Full Scale
Generator 250W 1MW
Structure Width 1m 11m
PTO Peak Torque 1.35Nm 19.7kNm
PTO Peak Speed 42.3rad/s 12.8rad/s
Optimal Wave Period 2s 6.6s

30. April 3rd, 2015 Asa Sproul 30

31. • RTI F2 tested
• Efficiency maximized through control
• Linear wave theory basis of control theory
• Sufficient test data captured for analysis and
improvements
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Overview

32. • RTI working on next set of prototypes
• RTI F2S and RTI F2DS
• Utilize swingarm and dual swingarm configurations
• Better economic feasibility
• Stronger structures
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Future Models

33. • Nathan Weise
• Duane Hanselman
• Bruce Segee
• John Rohrer
• Sean Lewis
• Matt Rowell
• Matt Hall
• Lance Doiron
• Arjun Prabu
• Adam Nickerson
• Lonnie Labonte
• Sara Lemik
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Special Thanks

34. April 3rd, 2015 Asa Sproul 34

35. • J. Vining and A. Muetze, “Economic factors and incentives for ocean wave energy conversion,” IEEE Trans. Ind. Appl., vol. 45, pp. 547–
554, March 2009. Slide 4
• http://upload.wikimedia.org/wikipedia/en/thumb/2/26/Maine_Black_Bears_Logo.svg/1280px-Maine_Black_Bears_Logo.svg.png Black
Bear image on section headers
• N. Ahmed and M. Mueller, “Impact of airflow impingment on heat transfer from induction generators in oscillating water columns,” in Proc.
International Conference on Power Electronics, Machines and Drives (PEMD), pp. 1–6, March 2012. LIMPET picture
• N. Muller, S. Kouro, J. Glaria, and M. Malinowski, “Medium-voltage power converter interface for wave dragon wave energy conversion
system,” in Proc. IEEE Energy Conversion Congress and Exposition (ECCE), pp. 352–358, Sept 2013. Wave Dragon picture
• R. Yemm, D. Pizer, C. Retzler, and R. Henderson, “Pelamis: experience from concept to connection,” Philosophical Transactions of the
Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 370, no. 1959, pp. 365–380, 2012. Pelamis picture
• A. F. de O. Falco, “Wave energy utilization: A review of the technologies,” Renewable and Sustainable Energy Reviews, vol. 14, no. 3, pp.
899 – 918, 2010. Power Buoy picture
• J. Falnes, Ocean Waves and Oscillating Systems. Cambridge University Press, 2002. Mass Spring Damper picture
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References