This document summarizes a thesis on the design and development of a marine current energy conversion system using a hybrid vertical axis turbine. The thesis aimed to design a low cut-in speed turbine, test it in a flume tank, and develop an experimental energy conversion system. Key points included: designing and testing a hybrid turbine prototype, obtaining test results showing its power output at various water speeds, and building a microcontroller-based conversion system with maximum power point tracking. The summary provides an overview of the objectives, methodology, results, and conclusions of the thesis work.

1. “ DESIGN AND DEVELOPMENT OF A
MARINE CURRENT ENERGY CONVERSION SYSTEM USING
HYBRID VERTICAL AXIS TURBINE ”
MD. JAHANGIR ALAM
MASTER OF ENGINEERING
FACULTY OF ENGINEERING AND APPLIED SCIENCE
MEMORIAL UNIVERSITY OF NEWFOUNDLAND (MUN)
ST.JOHN’S, NL, A1B3X5, CANADA.

2. Agenda
Agenda
Ocean Currents
Marine Current Energy Conversion System
Thesis Objective
Prototype Design
Flume Tank Test and Test Results
Experimental Energy Conversion System
Conclusions
1

3. Ocean/Marine Currents
Ocean Currents
Horizontal movement of the Ocean water known as Ocean
currents.
Mainly three types-
I. Tidal Currents
II. Wind driven Currents
III. Gradient (Density) Currents
Estimated total power = 5,000 GW
Power density may be up to 15kW/m2
Fig: Labrador Current
2

4. Tidal Currents
Ocean Currents
Vertical rise and fall of the water
known as Tides
Due to the gravitational attraction
of the moon and sun
Tidal Cycle of 12.5 Hours
Fig: Tides (due to Gravitational Attraction)
3

5. Gulf Stream +THC or Great Conveyor Belt
Ocean Currents
4

6. North Atlantic current (Near St. John’s)
Ocean Currents
Water Depth (m) Average Water Flow (m/s)
20 0.146
45 0.132
80 0.112
Near Bottom 0.07
Table: Ocean Current Speeds (for different depths)
at different areas of St. John’s, NL
5

7. Marine Current Energy Conversion System
MCECS
Power Electronic
Turbine Gearbox Generator Converter Battery
Mechanical Conversion Electrical Conversion
Figure: Marine Current Energy Conversion System (MCECS)
6

8. Thesis Objective
(As a part of ONSFI Project)
Design and Development of a low cut-in speed
turbine for SEAformatics pods.
System testing in a deep sea condition.
Design and Development of Signal Condition
circuits for the generated power.
Maximum Power Point Tracker development for
the designed conversion system.
7

9. Ocean Current Turbines
Turbines
Types of Turbine:
(According to OREG)
Fig. I: Vertical Axis Fig. II: Horizontal Axis
I. Vertical Axis Turbines
II. Horizontal Axis Turbines
III. Reciprocating Hydrofoils
Fig. III: Reciprocating Hydrofoils
8

10. Commercial Application
Turbines
Fig: Vertical axis (Blue Energy)
Fig: Reciprocating Hydrofoil
(Engineering Business Ltd.)
** High cut-in speed
** Turbine Rotation
Fig: Horizontal axis (MCT Ltd.)
9

11. Vertical Axis Turbines
Turbines
Vertical-axis turbines are a type of turbine
where the main rotor shaft runs vertically.
Types:
1. Savonius Type (Drag Type) (1) Savonius type
2. Darrieus Type (Lift Type)
I. Egg Beater Type
II. H-Type
Gorlov, Squirrel cage etc.
i. Egg Beater Type i. H-Type
[ Turbine rotation is irrespective to the direction
of fluid flow]
(2) Darrieus type
10

12. Comparison
Turbines
Savonius Type:
Adv.: High Starting Torque
Dis.: Low Tip Speed Ratio (TSR ≈<1), Low Efficiency
Darrieus Type:
Adv.: High TSR (>1), High Efficiency
Dis.: Low start-up characteristics
TSR (λ) = (Blade Tip Speed/ Water Speed)= (ωR/V)
11

13. Advantages of a Hybrid Turbine Design
Turbines
Flexibility to meet specific design criteria
Knowledge of conventional rotors
Simple in structure
Easy to build
12

14. Prototype Design

15. Possible Combinations
Prototype Design
Fig: Type A Fig: Type B
14

16. Selected Prototype
Prototype Design
Fig: Hybrid Model (CAD View) Fig: Hybrid Model (Final product)
Solidity Ratio: ((No. of Blades * Chord Length)/Rotor dia.)
15

17. Design Equations & Parameters
Prototype Design
Savonius Rotor
Rotor Height (Hs) 400mm
Mechanical Power Output Nominal diameter of the
of Hybrid Turbine, paddles (di) 130mm
Diameter of the shaft (a) 20mm
Rotor diameter (Ds) 200mm
P = 0.5× ρ × V3 × (AsCPs + (Ad - As )CP d ) Overlap ratio (β) 0.298
Swept area (As) 0.08m2
(I)
Darrieus Rotor
Tip Speed Ratio (TSR), Airfoil Section NACA 0015
Number of Blades 4
ωR d Solidity Ratio [3] 0.40
λ= (II)
V Rotor diameter (Dd) 1m
Rotor Height (Hd) 1m
Swept area (Ad) 1m2
Chord length (C) 100mm
Solidity Ratio: ((No. of Blades * Chord Length)/Rotor dia.)
16

18. Working Principle (Hydrodynamics)
Prototype Design
V= Water Speed
ωRd
Y
V VR
α
900 V = V 1 + 2 λ cos θ + λ 2
R
−1  sin θ 
α = tan  
1800 ө
 cos θ + λ 
00
X
2700 Counter clock
α
17

19. Flume Tank
Flume Tank Test
8m wide x 4m deep x 22.25m long
Fig: Flume Tank (MI) Fig: Turbine With Frame 18

20. Test Setup
Flume Tank Test
Magnetic Particle Load Cell
Brake
Gear-tooth
Submerged
Turbine
Gear-tooth
Sensor Torque Arm
Fig: Torque and Speed Measurement
Fig: Submerged Turbine
Fig: DAQ board and Data Collection Terminal 19

21. Test results

22. Savonius Test Results
Test Results
2.2
2
1.8
1.6
Power output, P (W)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Water Speed,V (m/s)
Fig: Two-Stage Savonius
Fig: Power (P) vs. Water Speed (V)
21

23. H-Darrieus Test Results
Test Results
14
12
Power output, P (Watt)
10
8
6
4
2
0
0 0.1 0.2 0.3 0.4 0.5 0.6
Water Speed,V (m/s)
Fig: Power (P) vs. Water Speed (V)
22

24. H-Darrieus Test Results
Test Results
0.14
0.13 V( m/ s )
0.12 0.3
0.11 0.4
0.5
Power Coefficient (Cp)
0.1
0.6
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1
TSR
Fig: Power Coefficient vs. TSR (λ) for H-Darrieus
Maximum Cp = 0.1248 @ 0.6m/s, when, TSR = 2.67
Maximum TSR = 3.09 @0.4m/s, when Cp = 0.012
23

25. Hybrid Test Results (P vs. V)
Test Results
22
20 Hybrid
Savonius
18
Darrieus
16
Power output, P (Watt)
14
12
10
8
6
4
2
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
VIDEO
Water Speed,V (m/s)
Fig: Power (P) vs. Water Speed (V) for Hybrid Turbine
24

26. Hybrid Test Results (P vs. ω)
Test Results
22
20
V ( m / s)
18 0.3
0.4
16 0.5
14 0.6
Power (Watt)
0.7
12 0.8
10
8
6
4
2
0
1.5 2 2.5 3 3.5 4 4.5
Turbine Speed (rad/s)
Fig: Power vs. Turbine Speed (ω) for Hybrid Turbine
25

27. Hybrid Test Results (C P vs. λ)
Test Results
0.16
V( m / s )
0.14
0.3
0.4
0.12 0.5
Power Coefficient (Cp)
0.6
0.1 0.7
0.8
0.08
0.06
0.04
0.02
0
2.5 2.6 2.7 2.8 2.9 3 3.1
TSR
Fig: Power Coefficient vs. TSR (λ) for Hybrid Turbine
Maximum Cp = 0.1484 @ 0.6m/s, when, TSR = 2.6794
Maximum TSR = 3.1114 @0.5m/s, when Cp = 0.0539
26

28. Experimental Energy Conversion System

29. Experimental Energy Conversion System
Experimental Conversion System
Hybrid PM DC/DC Battery
Converter Battery
Turbine Generator Charger
Rectifier Current and Voltage
PWM Sensing
Control
Signal
Dummy
Load Microcontroller
Power and Voltage
Calculation & PWM Duty
Cycle Calculation
RS232 Communication
LCD Display
User Interface
Fig: Experimental Energy Conversion System (MPPT based)
28

30. Maximum Power Point Tracker (MPPT)
Experimental Conversion System
P
Switch Mode MPP
Source PIN POUT Load
Power Supply
4 2
0 0
1 3
MPPT
Algorithm
MPPT Control v
Fig. MPPT Actions (Graphical View of P & O)
Fig. Basic MPPT control blocks
Case dP dv Action
0→1 <0 <0 +
2→0 <0 >0 -
3→0 >0 <0 -
0→4 >0 >0 +
Fig. MPPT Actions
29

31. MPPT Algorithm (Perturbation & Observation)
Experimental Conversion System
Fig: MPPT Flow Chart
30

32. Detailed Circuit Diagram
Experimental Conversion System
31

33. Main features
Experimental Conversion System
Low cost microcontroller based
Less complexity
Easily extendable
Minimize the size due to less components
32

34. Laboratory Setup
Experimental Conversion System
DC Supply
Current
Sensor
Boost Converter LOAD
Dummy
Load
Microcontroller with
RS232 and LCD Display
Battery 12 V
33

35. Test Result (Boost Converter)
Experimental Conversion System
222 µH MUR815
Diode
30
27 Theoretical
24 Experimental
Output Voltage, Vout (V)
IRL 520
1300 µF 21
MOSFET (Logic level)
18
Fig: Boost Converter 15
12
9
6
3
0
0 1 2 3 4 5 6 7 8 9 10
Input Voltage, Vin (V)
Fig: Vout vs. Vin
34

36. Test Result (MPPT)
Experimental Conversion System
PWM Signal
Vout
Fig: Oscilloscope shots of PWM Signal and Vout
Vin
Vout = & Iout = Iin (1 - D)
(1 - D) ** 5 Volt/Div 35

37. Conclusions

38. Thesis Contribution
Conclusions
A simple, low cut-in speed, high TSR, lift type hybrid turbine
has been designed.
Designed turbine has been built, tested and analyzed in a
real world situation.
A low cost microcontroller based experimental energy
conversion system has been built and tested.
A MPPT control algorithm has been tested for the design
conversion system.
37

39. Future Work and Suggestions
Conclusions
More water speed data should be collected at other areas of St.John’s.
A CFD (Computational Fluid Dynamics) analysis should be done before
the actual design and test.
To get a higher torque at a comparatively low TSR, cambered airfoil (for
example, NACA 4415) can be used.
A low speed DC PMG can be used to avoid gearbox and rectifier losses.
More sophisticated MPPT algorithm and digital filtering can be
introduced in the control system.
38

40. Acknowledgements
Supervisor:
Dr. M. Tariq Iqbal
SEAformatics Group:
Dr. Vlastimil Masek
Dr. Michael Hinchey
Andrew Cook
Paul Bishop
Brian Pretty
Nahidul Islam Khan
Sanjida Moury
39

41. Publications
“Design and Development of Hybrid Vertical Axis Turbine”
presented at 22nd CCECE’09, St.John’s, NL, Canada, 03-06
May, 2009, pp.1178-1183.
“A Low Cut-in Speed Marine Current Turbine” submitted to
Journal of Ocean Technology, 2009.
40

42. Thanks