Design Review for Scaled Autonomous Wave Energy Converter Prototype

Timothy M. LewisBret Bosma

School of Electrical Engineering and Computer Science

Oregon State University

July 18, 20121

Design Review Topics

• Prototype and Testing Goals • Mechanical Configuration • Electrical One-line Diagram • Bill of Material

• With Cost Estimates• Integration and Wave Tank Test List

• With Estimated Testing Cost• Schedule

• Fabrication and Integration• Testing (Linear Test Bed and Wave Flume Testing)

• Risks • Conclusion

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Prototype and Testing Goals

• Prototype Overview– Modified base design to be an 8m spar so that scaled prototype will fit

in the wave flume– This necessitates moving the dominant frequency of interest from 6

sec. to 4 sec.– Geometrics scaling will be used (1:4). This results in a 2 m long scaled

prototype– Prototype has externally mounted electric machine to allow for a

more simple spar/float connection, i.e. no CFTS

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Prototype and Testing Goals

• Testing Goals– Generate test data in the wave flume for comparison with both

OrcaFlex and AQWA predicted results• Validate power output vs. predicted• Validate linearized model parameters vs. predicted

– Test linearized model parameters vs.» Wave height» Wave period

• Test control algorithms– Binary optimal control– Binary optimal control (modified dampening)

» Measure dP/dz type of data– Ternary optimal control (with accelerometer data)

• Test conditions– Monochromatic 4 sec (scaled value = 2 sec) wave input– Spectral wave input

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Mechanical Configuration

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Mechanical Configuration

• View Solidworks slideshow

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Bill of Material (Solidworks)

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ITEM NO. PART NUMBER DESCRIPTION Desc1 QTY.1 RE-max29 spindle drive motor 12 GP32C spindle drive spindle 1

3 GP32C-N spindle drive spindle nut part of spindle drive 1

4 AWEC0002 motor support 6061-T6 (SS) 1

5 AWEC0008 ballscrew support 6061-T6 (SS) 1

6 AWEC0001 Top Spar Cap 6061-T6 (SS) 1

7 AWEC0003 spar support shafts 440C Series Stainless Steel 4

8 1305T172 float support shafts 440C Series Stainless Steel 4

9 6338K422 bushings for ball screw support Bronze Flanged Sleeve Bearing 4

10 AWEC0007 float top 3/4" PVC 111 16x24SCH40 float outer SCH40 PVC 16" OD 1

12 6x24PVCROD float inner Machined from rod 1

13 AWEC0006 float bottom 3/4" PVC 114 84945K116 float bearing material 3/4" UHMW 215 48855K17 spar body Schedule 80 PVC 3.5in OD 116 AWEC0004 bottom of spar plug PVC 117 8747K149 damping plate 3/8" PVC 118 AWEC0005 mounting sleeve for damp plate 6061-T6 (SS) 2

19 92290A168 motor mount and spindle nut screws M4 Screw 316 SS 20mm 8

20 92185A542 float and spar screws 1/4"-20 Type 316 Stainless 36

21 94150A335 motor mount and spindle nut nuts Hex nut, M4 x 0.7 Type 316 822 63215K52 spindle drive support bearing Ball Joint 1

23 92185A548 screws for damp mount sleeve 1/4“-20x1.75" Type 316 Stainless 2

24 94804A340 motor and float support nuts 1/2"-13 Nuts Type 316 Stainless 16

Bill of Materials Outstanding Hardware

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FIND NO. QTY U/M PART NUMBER DESCRIPTION Function SUBTOTAL TOTAL

1 1 EA 48855K17 10'length 3.5"OD 2.865"ID Thick-Wall (Schedule 80) Dark Gray PVC Unthreaded Pipe

spar body $46.13 $46.13

2 1 EA 63215K52 1/4" ID 21/32" OD Ball Joint Swivel Bearings Stainless Steel Housing with Stainless Steel Insert

spindle drive support bearing $15.62 $15.62

3 1 EA 84945K116 3/4" THICK 12"x12" Oil-Filled UHMW Polyethylene float bearing material $35.54 $35.54

4 4 EA 6338K422 1/2" shaft 3/4"OD Bronze Flanged Sleeve Bearings bushings for ball screw support $1.38 $5.52

5 3 EA 1305T172 1/2" Dia. 72" length Stainless Steel Hardened Shafts spar and float support shafts $35.90 $107.70

6 1 EA   6" Dia. 2' length PVC Rod float inner $194.29 $194.29

7 1 EA 8747K186 3/4" thick 36"x36" PVC sheet float top and bottom $156.14 $156.14

8 1 EA   16"OD 16"length Schedule 40 PVC float outer $79.77 $79.77

9 1 EA 94150A335 M4 Hex Nut Type 316 Stainless 50/pkg motor mount and spindle nut nuts $3.42 $3.42

10 1 EA 92290A168 M4 x 20mm Socket Head Screw Type 316 Stainless 25/pkg motor mount and spindle nut screws $7.72 $7.72

11 2 EA 94804A340 1/2"-13 Hex Nut Type 316 Stainless 10/pkg motor and float support nuts $5.47 $10.94

12 1 EA 8747K149 3/8" type 1 pvc 24"x24" damping plate $39.83 $39.83

13 1 EA 92185A548 1/4"-20x1.75 Socket Head Screw Type 316 Stainless 10/pkg screws for damp mount sleeve $6.67 $6.67

14 4 EA 92185A542 1/4"-20x1 Socket Head Screw Type 316 Stainless 10/pkg float and spar screws $4.16 $16.64

               

               

Total $725.93

Total Cost• Hardware BOM:

– Bottoms up estimate: $725– Additional misc. and shipping of above $750

• Estimate for Fabrication Costs (Manfred):– 30 hrs. @ $82/hr = $2460

• Data Acquisition and Control: – Accelerometer: $200 for low cost version – Requires use of dSpace control rack

• Modification for LTB:– $200 for material plus 8 hr ($656) for mechanical work

• Hinsdale Lab Use: – $19,400 (detailed below)

• Spent to date (Spindle drive, electronics, and cables)– $1894

• Total cost: $2628510

Integration and Wave Tank Test List

• Integration Tests – Benchtop testing of electronics

• Spindle drive assembly with servo and DC electric machine– Spindle drive assembly to arrive early August

• Integration and testing of accelerometers• dSpace control integration

– LTB• Verification of PTO performance with monochromatic wave• Verification of expected movement (position, velocity,

acceleration)• Initial course control/matching tuning• Testing of alternate control algorithms

• Integration: Final assembly and checkout

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Integration and Wave Tank Testing

• Hinsdale testing– $2800 per day for OSU internal rate

• $400 per hour– 2 days setup ($5600)– 1 day tear down ($2800)– 5 min per test monochromatic wave– 10 min per test spectral wave– 15 min between tests– 7 hrs per day

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Integration and Wave Tank Testing

• Hinsdale Tests– Min wave height, target wave period (mono), binary optimal control

• 25 runs to match simulations• Estimate 8 runs to ensure in the target area• 33 x 15 min => $3300

– Min wave, target wave period (mono), ternary optimal control• 25 runs to match simulations• 25 x 15 min => $2500

– Target wave period (mono), binary optimal control, sweep wave height• 10 runs to match simulations• 10 x 15 min => $1000

– Min wave height, binary optimal control, sweep wave period (mono)• 10 runs to match simulations• 10 x 15 min => $1000

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Integration and Wave Tank Testing

• Hinsdale Tests– Spectral wave series, binary optimal control

• 8 runs• 8 x 20 min => $1066

– Spectral wave series, ternary optimal control• 8 runs• 8 x 20 min => $1066

– Spectral wave series, wideband control• 8 runs• 8 x 20 min => $1066

• Totals: – $19,400– 7 days

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Schedule

• Review Excel spreadsheet schedule

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Risks

• Friction amount due to low power levels– Mitigation: High quality lead screw. Get initial friction numbers early.

Test friction of bushings.• Hinsdale wave test time

– Mitigation: Use the LTB for early validation. Use static water tank for buoyancy calibration and initial parameter determination (motor mode). Calibrate all data acquisition and sensors early.

– Mitigation: Bret’s fall wave tank testing with CPT• Use of low cost accelerometer

– Mitigation: Low cost one is cheap so easy to try but higher quality ones are approximately $2-3K

• Hinsdale wave tank mooring design– Mitigation: Potentially we could use NREL/CPT/OSU controlled

moored system

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Modeling Notes

• Model update. The full scale model simulation will have to be run again since practical aspects of prototype design slightly changed the geometries.– This is stated as more of a realization that the initial predictions will

have to be updated

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Conclusion

• The scaled prototype design meets the intent for wave tank testing and FEA design validation

• A balance between the original AWEC design and testability/fabrication has been used

• It is felt most of the known risk areas have been addressed

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