1. Aishwarya Kumar (2010102002)
Bhargavi Ganesh (2010102014)
Deepika Ramesh (2010102018)

2. •OffshoreWindTechnology
•Objectives of Project
•Methodology
•Design of Structure
•Results
•Conclusion

3. • Introduction
• Global Scenario
• Potential and Application in India

4.  To conduct the structural analysis of
possible supporting structures for an
offshore wind turbine
 To design a suitable supporting structure in
accordance with the specific site conditions

5. •Introduction
•Software Used
•Schematic Diagram of Methodology
•*Load Estimation & Load Cases
•*Input parameters
•Power Production at Site

6.  Capacity of selected turbine: 1.5 MW
 Location of Site: Off the coast of Rameshwaram
 Steps involved:
STAGE I: Load Estimation
STAGE II: Soil Structure Interaction
STAGE III: Structural Analysis & Design
STAGE IV: Power Production at Site
 Software Used:
1) FAST (developed by NREL)
2) USFOS (developed by SINTEF marintek & NTNU)

7. Stage Code/Theory based on
Software
Used
I. Load Estimation
Aerodynamic Loads on turbine IEC 61400 – Part 1 (2005) FAST
Hydrodynamic Loads on tower Airy’sTheory,
Morrison Equation
USFOS
Wind Loads on tower IS 875 – Part 3 (1987) USFOS
II. Soil Structure Interaction API RP 2A-WSD (2007) USFOS
III. Structural Analysis & Design IEC 61400 – Part 3 (2009),
API RP 2A-WSD (2007)
USFOS

8. STAGE I: Load
Estimation
•Aerodynamic
•Hydrodynamic
•Wind
STAGE II: Soil
Structure Interaction
•Foundation: Monopile
•Modeled as springs in
axial and lateral
direction at every 5 m
STAGE III: Structural Analysis &
Design
•Safety criteria: Displacement &
Interaction Ratio
•Designed such that criteria were
met

10.  Data obtained: Wind speeds at
10 m & 20 m above MSL from
September 1991 to August 1993
 Collected at site in Rameshwaram
(09°13’40”N, 79°20’35”E)
 Power Law used to extrapolate
speeds at different elevations
 Power curve generated for site
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25 30
Power(kW)
Wind Speed (m/s)
Power Curve

11. Turbine Parameters
Capacity ofTurbine 1.5MW
WindTurbine Class Class 2
Turbulence Category B
Cut-in Speed 5.0 m/s
Rated Speed 11.5 m/s
Cut-out Speed 25.0 m/s
Rotor Diameter 70.0 m
Hub Height
84.3 m (from MSL to hub
of turbine)
Tower Parameters
Tower Height 80.0 m
Diameter ofTower 4.0 m
Thickness ofTower 0.05 m
Material ofTower Steel
Pile Parameters
Type of Foundation Monopile
Diameter of Pile 3.5 m
Thickness of Pile 0.085 m
Length of Monopile 30.0 m (below mudline)
Length of Monopole 15.0 m (above mudline)
Material of Pile Steel
Young’s Modulus of Steel 200,000 MPa
Yield Strength of Steel 250 MPa
Turbine parameters are defined by the
manufacturer –This study uses the
properties defined by NREL (inbuilt in
FAST)

12. Design of
Structure
Tower Height = 80 m
Hub Height = 85 m
Monopile Length= 30 m
Monopole Length = 15
m
Depth of Water = 10 m
Total Height of
structure above mudline
= 95 m
Turbine
Tower
Monopole
Monopile
30m15m80m
10m85mMSL
Mudline

13. •Displacement & Interaction Ratio
•Capacity ofTower
•Bending Moment & Shear Force Diagrams
•Simulation on USFOS
•Power Production

14. DISPLACEMENT
 According to Nicholson
(2011):
Limiting value: 1.25% of height
of structure above mudline
(i.e. 95 m) (=1.1875)
INTERACTION RATIO
 According to API RP 2A-
WSD (2007):
Limiting value: 1
MaximumValue Corresponding Case
Displacement 1.16789 m ECD-R+2
Interaction Ratio 0.5979 EWM50
ECD-R+2: Extreme Coherent Gust with Direction Change when wind velocity at hub = Rated
speed + 2 m/s
EWM50 : ExtremeWind Speed Model with recurrence period of 50 years

15. Displacement &
Interaction Ratio
•The highest value of
displacement obtained
was for Case No. 6. (ECD-
R+2). It occurred at a time
instant of 53.1 s.
•For Extreme Wind speed
Models (EWM), the rotor
stops rotating because the
cut-out speed is reached in
such extreme conditions.
Thus, displacements in
these cases are not
considered for analysis.

16. 0
100
200
300
400
500
600
700
800
374 376 378 380 382 384 386
BaseShear(KN)
Time (sec)
TIME-HISTORY RESPONSE OF BASE SHEAR
Maximum
Base Shear
0
10000
20000
30000
40000
50000
60000
68 70 72 74 76 78 80 82
OverturnMoment(KNm)
Time (sec)
TIME-HISTORY RESPONSE OF OVERTURN MOMENT
Maximum
Overturn
Moment

17. Parameter Value
Maximum Base Shear 726.735 kN (at 380.1 s)
Maximum Overturn Moment 5.01 x 104 kNm (at 75.1 s)
MaximumTotal Axial Load 5.11 x 103 kN
Factored Pile Axial Capacity 1.19 x 104 kN
Factor of Safety 2.5
All the aforementioned maximum values were found to be for the loading
case ECD-R+2. Pile capacity was calculated as per API RP 2A-WSD.

18. B
B) Shear Force Diagram for the
Tower under ECD-R+2 loading
condition at the 53.1 s
A) Bending Moment Diagram for the
Tower under ECD-R+2 loading
condition at the 53.1 s
A
*Maximum Displacement occurred for this case at 53.1 s
*Maximum Displacement occurred for this case at 53.1 s

20. 0.00
5.00
10.00
15.00
20.00
25.00
09/91 12/91 04/92 07/92 10/92 01/93 05/93 08/93
WindSpped(m/s)
Time (MM/YY)
Wind Speed (Hub Level)
0.00
500.00
1000.00
1500.00
09/91 12/91 04/92 07/92 10/92 01/93 05/93 08/93
PowerProduction(kW)
Time (MM/YY)
Power Production - 1.5 MW
726
1345
2306
2734
3003
2836
2389
1411
605
148
39 2 00
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
0-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-20 20-22 22-24 24-26
FREQUENCY
DISTRIBUTION
OF WIND
SPEEDS AT
HUB
Frequency
Wind Speed at Hub Height (m/s)
For the Rameshwaram site (using
Power Curve generated):
•Average wind speed = 9.14 m/s
•Standard deviation of wind speed
= 4.12
•Avg. power generated = 0.781 MW
• Plant Load Factor = 0.52

21.  India has potential to support Offshore Wind
Technology
 A 1.5 MW capacity turbine gives a PLF of 0.52 at
the Rameshwaram site
 Based on analysis, the proposed design is
structurally feasible – further studies are
needed for cost analysis