wave and wind power seminar - cesos.ntnu.no · 1 introduction by torgeir moan, cesos wave and wind...
TRANSCRIPT
![Page 1: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/1.jpg)
1
Introduction by
Torgeir Moan, CeSOS
Wave and wind power seminarwith a focus on
the use of floating facilities
CeSOS, May 27. 2008
2
WIND
LAND
HEAT
OCEAN-waves
-currents
Sources of renewable energy- of primary interest to Norway
Facilities for transforming the energy into- electrical energy- possibly other uses
Solar cell
3
Source: Tande, SINTEF
Wind in Norway4
Wind turbine concepts
Bottom supported Buoyantsupport structures
tower
bladehub
nacelle
5 MW
![Page 2: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/2.jpg)
5
PelamisWaves
Prototype: 750 kW
Power conversion module
The Pelamis during sea trials (Picture from Ocean Power Delivery)
6
Fred Olsen conceptWaves
Rotor/flywheel for smoothing energy
Transfer of wave motioninto electric power:- hydraulics- mechanical- direct drive (linear generator)
7
3D Model of the Point absorber (Picture from Danish Wave Energy)
Principal drawing of thePoint Absorber (Picture from Rambøll)
Schematic of the Aquabouy
Other devices for converting wave power
And devices for converting current power(resembling wind turbines)
8
Site specific design criteria• Wave- wind climate • Bathymetry• Facilities for maintenance
Platform hierarchy/clustering• Platform grouping• Farm control• Replacement of units
Electrical infrastructure• Net connection• Connection between
platforms to main platform(s)• Smooting power
System configuration of power- producing units
![Page 3: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/3.jpg)
9
Data, methods,criteria
Fabrication & Operation
data
Layout/Scantlings
Design for- serviceability &- producability- safety
Fabrication &installation- Fabrication plan -- Inspection/repair
Operation- Operation plan
Inspection/monitoring/ repair / maintenance
Removal and reuse
Reassessment
Life Cycle Phases of Marine Structures
Example: Spar wind turbine
+ Installation ofthe mooring system
10 The challenges
A) Power production- Power = Force · velocity- Power smoothing
B) Safety for Man, Environment and PropertyEnvironmental issues relating to
- occupation of space - oil leaks
Life cycle costs- fabrication & installation- maintenance and repair due todamages due to extreme events, fatigue and wear and tear
Optimal solution ?
Ratio of power producing forces and maximal forces in the system n)- shut down during worst load scenarios (”load shedding”)
Survivability beforePower Capture Effect
11
Aim & Scope of this seminar• Power production
- basic principles- equipment
• Availability & Safety
• Dynamic modelling of the integrated system
Functionality BeforeLunch
Afternoon
the environment mechanical/ electricalhydraulic generator
Identify challenges
12
Program
Power generation 0915 Wave power – some basic principles and use of latching by Professor Johannes Falnes, NTNU 1000 System modelling and application of automatic control of wave power
(wave motion, hydraulics, electric generator) by Jørgen Hals, CeSOS
1030 Power production in a wave energy converter – Effect of controls and operational constraints by dr. Karl Erik Kaasen, MARINTEK
1100 Break
1115 Wind induced power – basic principles of power take-off and equipment by Professor Ole Gunnar Dahlhaug, NTNU 1215 Lunch Dynamic analysis of floating systems subjected to wave- and wind loads 1315 Introduction by Professor Torgeir Moan, CeSOS 1330 Dynamic modelling of multi-body structures – for wave power generation by Reza Taghipour, CeSOS 1400 Dynamic modelling of wind turbines under combined wave and wind loading by Dr. Rune Yttervik, StatoilHydro 1430 Coffee break 1445 Mooring of floating plants by Dr. Zhen Gao, CeSOS 1515 Discussion: Challenges for the future. 1600 End of the day
![Page 4: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/4.jpg)
1
1
Wave power:Some basic principles and use of latching control
Johannes Falnes
Lecture at CeSOS seminar,
NTNU, Trondheim, 27 May 2008:
Institutt for fysikk, NTNU&
Centre for Ships and Ocean Structures, NTNU
http://folk.ntnu.no/falnes http://www.ntnu.no/fysikk http://www.cesos.ntnu.no
2
Renewable energy
WIND
LAND
HEAT
OCEAN
Global resource of renewable energy:
Energy flow from the sun to our planet: ∼1017 W
Power in all the world’s winds: ∼1015 W
Power in all the world’s ocean waves: ∼1013 W
![Page 5: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/5.jpg)
2
3
Wind energy is more persistant than solar energy. Winds may blow during nights.
Wave energy is more persistant than wind energy. Swells may exist in cases of no wind.
We have more wind energy and wave energy in winter than in summer.
4
•
••• Wave energy: 2 - 3 kW/m2
• Average energy intensity:
• Solar energy: 100 - 200 W/m2
•
•• Wind energy: 400 - 600 W/m2
![Page 6: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/6.jpg)
3
5
• As we have seen, the water particles move in circles with decreasing radius in the depth. Consequently, the energy flow density decreases as we go deeper in the water. In fact, on deep water, 95 % of the energy transport takes place between the surface and the depth L/4. (L is the wavelength).
Vertical distribution of wave-energy transport
Dep
th
2
4
6
8
3,0 kW/m2
1,3 kW/m210 m
Water level
H = 2 m and T = 10 s
kW/m21 0 3 2
J = 40 kW/m
6
Ring-shaped waves from a stone dropped into a calm lake
Photo: Magne Falnes, 1999
![Page 7: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/7.jpg)
4
7
Swells propagating across the Pacific
• Since the group velocity is proportional to the period, low-frequency waves move faster away from a storm centre than high-frequency waves. The figure shows the situation 4 days after a storm with centre located at 170º east and 50º south.
T = 20 s
T = 18 s
T = 16 s
T = 14 s
T = 12 s
T = 10 s
Period
-10
-20
-30
-40
180 190 200Source: OCEANOR, Norway
8
Energy content of waves• For a sinusoidal wave of height H, the average energy E stored on a
horizontal square metre of the water surface is:
• Half of this is potential energy due to water lifted from wave troughs to wave crests. The remaining half is kinetic energy due to the motion of the water.
2HkE E=
2s/mkW 52m:Example ⋅=⇒= EH
kE = ρ g / 8 = 1.25 kW ·s/m4
ρ = mass density of sea water ≈ 1020 kg/m3
g = acceleration of gravity ≈ 9.8 m/s2
![Page 8: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/8.jpg)
5
9
Energy transport in waves• The energy transport per metre width of the wave front is
2THkJ J=
kW/m402m and s10:Example
=⇒== JHT
EcJ g=
On deep water the group velocity is cg=gT/4π, which gives
kJ = ρ g2 / 32 π ≈ 1 kW/m3s
10
Governmental funding of wave-power R&D from 1978.
UKNorwayTrondheimNTH
Those who cannot remember the past are condemned to repeat it.(George Santayana, 1863–1953, American philosopher. In 1905 in his treatise ”The Life of Reason”.)
No substantial increase in Norway during 1995-2008
![Page 9: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/9.jpg)
6
11
Kjell Budal(1933-1989)
- initiated wave power research at NTH, Trondheim, 1973- already in 1977 made a theoretical study of wave-power
absorption by a group of interacting oscillating bodies- invented many different types of wave-power buoys- proposed latching control of phase (and amplitude)- advocated reasonably small power buoys, operating at
full capacity a rather large fraction of the year
12
• Absorption of wave energy from the sea may be considered as a phenomenon of wave interference. Then wave energy absorption may be described by an apparently paradoxical statement:
• To absorb a wave means to generate a wave • or, in other words:
• To destroy a wave is to create a wave.
A paradox?
![Page 10: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/10.jpg)
7
13
Incident wave + reflected wave = standing wave
• Incident wave
• Wave reflected from fixed wall
• Interference result: Standing wave composed of incident wave and reflected wave
=
+
14
=
+
• Incident wave
• Wave reflected from fixed wall• Wave generation on otherwise
calm water (due to wall oscillation)
• Result: The incident wave is absorbed by the moving wall because the reflected wave is cancelled by the generated wave.
“To absorb a wave means to generate a wave”- or “to destroy a wave means to create a wave”.
![Page 11: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/11.jpg)
8
15
Array of buoys in heave and in surge/pitch
incident wave
radiated by heave
radiated by surge/pitch
d = a+b+c, superposed
To absorb a wave means to generate a wave.
[Illustration from: Falnes, J. and Budal, K.: "Wave power conversion by point absorbers". Norwegian Maritime Research, Vol 6, No 4, pp 2-11, 1978.]
16
Two upper bounds PA og PB for the power P that can be absorbed by means of an oscillating body of volume V when the wave is sinusoidal with period T and amplitude H/2. [Figure 2 in the paper: Falnes, J. "A review of wave-energy extraction". Marine Structures, Vol 20, No 4, pp 185-201, 2007. (DOI: 10.1016/j.marstruc.2007.09.001)]
![Page 12: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/12.jpg)
9
17
Budal's latching-controlled-buoy type wave-power plant
J. FALNES and P.M. LILLEBEKKENInstitutt for fysikk,
Noregs teknisk-naturvitskaplege universitet (NTNU),N-7091 Trondheim, Norway
Paper published inFifth European Wave Energy Conference: Proceedings of an International Conference held at University College Cork, Ireland, 17-20 September 2003. (Edited by Anthony Lewis and Gareth Thomas. Organised & Published by Hydraulics & Maritime Research Centre, Cork, Ireland, 2005, ISBN 0-9502440-5-8), pp. 233-244, [http://folk.ntnu.no/falnes/w_e/budal_latch_buoy_2003.pdf]and presented 2003-09-19 at the 5th European Wave Energy Conference:
Most of the presentation given 2003-09-19 is indicated on the following slides:
18
t
Optimal phase at resonance
Phase control by latching
[Reference: Falnes, J. and Budal, K.: "Wave power conversion by point absorbers". Norwegian Maritime Research, Vol 6, No 4, pp 2-11, 1978.]
![Page 13: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/13.jpg)
10
19
Video clip A (mpg): Latching-controlled buoy models in wave channelReference: Budal, K., Falnes, J., Kyllingstad, Å. and Oltedal, G.: "Experiments with point absorbers". Proceedings of First Symposium on Wave Energy Utilization, Gothenburg, Sweden, pp 253-282, 1979. (ISBN 91-7032-002-0)
20Video clip C (mpg): Latching-controlled buoy of type E in wave tank
[Video clip on http://folk.ntnu.no/falnes/w_e/index.html]
![Page 14: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/14.jpg)
11
21
Point absorber of "type E" with hydraulic machinery.
V1 - controllable valveV2, V3 - check valvesA1, A2, A3 - gas accumulatorsA1 is for latching controlA2 - high pressure accumulatorA3 - low pressure accumulatorM - hydraulic motor (turbine)
MC - mooring cable (or rod)PR, P - piston rod, pistonC - hydraulic cylinder
22
Building-up of latching-controlled buoy's heave oscillation to a stroke length of 0.8 m in wave of height 0.16 m and period 3.1 s. (Type E buoy model test)
![Page 15: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/15.jpg)
12
23
Upper graph shows the force in the mooring strut varying over a 9-kN range.
Lower graph shows: Building-up of input energy Eb from 5.6 kJ to 11.4 kJ during 25 s when the incident wave has a height (0.18 ± 0.02) m and a period 3.1 s.
(Type E buoy model test.)
24Video clip D (mpg): Latching-controlled buoy of type M2 in wave tank
[Video clip on http://folk.ntnu.no/falnes/w_e/index.html]
![Page 16: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/16.jpg)
13
25
Point absorber of "type M2" with pneumatic machinery.
C, P, PR - cylinder, piston, piston rod RD - diaphragm seals, A2 - energy-storing gas accumulatorV2 and V3 - rectifying check valves AI and AO - air inlet and outlet pipesER - engine room containing turbo-generator. Mooring strut MS, connected to universal joint UJ, is pre-tensioned by pressure in accumulator A1.Relative motion of the buoy along piston rod PR may be latched/unlatched by activating/deactivating mechanism L. The system is provided with guiding rollers G, end stop buffers ES, ballast weight W, and rolling diaphragm seals RD.
26
Array of point absorbers (latching-controlled buoy of type N2)
Source: SINTEF, Trondheim, Norway, 1982.
[Illustration used in White paper: Om nye fornybare energikilder i Norge, St.meld. nr. 65 (1981-82), The Royal Ministry of Petroleum and Energy, Oslo, 1982,and in Budal, K., Falnes, J., Iversen, L.C., Lillebekken, P.M., Oltedal, G., Hals, T., Onshus, T. and Høy, A.S.: "The Norwegian wave-power buoy project". Proc. Second International Symposium on Wave Energy Utilization(H. Berge, ed), pp 323-344, 1982. Tapir, Trondheim, Norway. (ISBN 82-519-0478-1)]
![Page 17: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/17.jpg)
14
27
Power buoy of type N2.
Buoy hull B, connected to submerged weight W, through cables C, is arranged to move along mooring strut MS
Buoy hull B, connected to submerged weight W, through cables C, is arranged to move along mooring strut MS, connected to universal joint UJ on anchor A. Hull B contains a latching mechanism and an OWC with rectifying valves, air turbine and electric generator.
28Video clip E (mpg): Latching-controlled buoy of type N2 in sea
[Video clip on http://folk.ntnu.no/falnes/w_e/index.html]
![Page 18: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/18.jpg)
15
29
Model (in scale 1:10) of power buoy of type N2. B – hull (diameter 1 m), open in the bottom, for providing communication with an internal OWC. BC – annular air chamber providing buoyancy. G –guiding rollers MS – mooring strutL – latching mechanismD – air duct O – calibrated orifice SS – supporting stay FW – flow-evening housing UJ – universal joint A – anchor
30
Experimental results from sea tests with N2 model.
Absorbed power Pa (measured) versus theoretical estimate Pt.The square points (red) obtained with modified buoy hull.
![Page 19: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/19.jpg)
16
31
Modified hull
- larger opening
- larger radius of curvature
[Illustration used in 1993 paper # 111 as specified in the publication list http://folk.ntnu.no/falnes/w_e/publwave.html.]
32
Hs /m T-1 /s J /Wm-1 Latching strategy Pa /W (Pa /J)/m0.24 2.5 69 2 latchings/cycle 18 0.260.24 2.5 69 1 latching/cycle 16 0.230.22 2.5 58 Latched all time 7 0.12
Power absorbed for three consecutive runs of the N2-buoy model, with different latching strategies.
The significant wave height Hs was slightly reduced at the time when the third run was made.
Different latching strategies.
![Page 20: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/20.jpg)
17
33
– upper graph –and one latching interval per oscillation cycle ("mode 2") –lower graph – .
Measured values (in metres) of the N2 model position relative to the strut, during 100 seconds. Two latching intervals per oscillation cycle ("mode 1")
34
Measurements from another "mode-2" run with the sea-tested N2 model.
Buoy velocity relative to the strut (in m/s) and of the hydrodynamic pressure (in kPa) at the collar on the strut, which pressure is a measure of the wave.
![Page 21: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/21.jpg)
18
35
Acknowledgements.
Jørgen Halsdrew the illustrations used in slides 2, 5, 13, 14, 16 and 18 of this presentation.
Per Magne Lillebekkendrew the illustration used in slide 10, and from an existing analogue video, he also digitalised the video clips shown during the presentation (corresponding to present slides 19, 20, 24 and 28.)
36
Those who cannot remember the past are condemned to repeat it.(George Santayana, 1863–1953, American philosopher. In 1905 in his treatise ”The Life of Reason”.)
![Page 22: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/22.jpg)
1
1
J. Hals: Power take-off systems for wave energy converters
Power take-off systems for wave energy converters
Jørgen Hals, PhD studentCentre for Ships and Ocean Structures (CeSOS)Norwegian University of Science and Technology (NTNU)Norway
NTNU Marinteknisk senter, 27 May 2007
2
J. Hals: Power take-off systems for wave energy converters
Outline
Some aspects of wave power and its conversionThe three main roads to electricityProperties compared
Source
: Nati
onal
Ocean
ic an
d Atm
osph
eric A
dmini
strati
on, U
S
![Page 23: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/23.jpg)
2
3
J. Hals: Power take-off systems for wave energy converters
Scope...
limited to oscillating systems, not over-topping devicesconversion to electricity
Source: Hagerman
4
J. Hals: Power take-off systems for wave energy converters
Power flow in wave energy conversion
![Page 24: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/24.jpg)
3
5
J. Hals: Power take-off systems for wave energy converters
The equation of motion- machinery force
( ) ( )m mF t R tη= − &
( ) ( ) ( )m m mF t R t S tη η= − +&
( ) ( ) ( ) ( )m m m mF t m t R t S tη η η= − + +&& &
( ) ( ) ( )m mF t R t tη= − &
( )( ) ( ), ( ), ( ), ( ),m eF t f t t t F t tη η η= & &&
( )( ) ( ) ( ) ( ) )( ) () (r r mem m t R t S t F t F tω η ω η η+ + + = +&& &
accelerated mass radiated waves buoyancyforce
waveexciation
force
machineryforce
|
PTO
R 5.0 m
η
z
x
( ) ( ) ( )m mP t F t tη= &
Useful power:
6
J. Hals: Power take-off systems for wave energy converters
Instantaneous power
The minimum peak-to-average power ratio is 2, but in practice considerably higher → need for energy storageTypical machinery force in the order of 1 MN.
-10
10
30 Instantaneous power
0 5 10 15 20 25 30 35 40time {s}
-1-0.5
00.5
1Position
Source: Henderson., 2006
![Page 25: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/25.jpg)
4
7
J. Hals: Power take-off systems for wave energy converters
The three main roads to electricity(seen today...)
Air turbine (+generator)Hydraulic pump (+generator)Direct-coupled electric generator
8
J. Hals: Power take-off systems for wave energy converters
Air turbines – used for OWCs
Wells turbineImproving performance through
– guide vanes– blade pitching– counterrotating turbines
Close to linear P/Q relationship
Impulse turbineImproving performance through
– guide vane design and pitching
Self-startingNo stallNonlinear P/Q relationship
Source: JAMSTEC, JapanSource: Setoguchi et al., 2001
Inherent energy storage in shaft rotationPneumatic gearing
![Page 26: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/26.jpg)
5
9
J. Hals: Power take-off systems for wave energy converters
Efficiency for air turbines
Average efficiencies in operated plants typically range from 35 to 50 %(pneaumatic to shaft power)
Source: Setoguchi et al., 2001Source: Richard Curran and Matthew Folley, 2008
10
J. Hals: Power take-off systems for wave energy converters
Hydraulic systemsHydraulic pumps, rotary or linearFluid power equipment easilyavailable, but not optimised withregard to lossCan take large forces and largepowerHigh power densityNeed for lubrificationNon-linear force characteristicEfficiency in the range 0.5-0.8 (mechanical to motor shaft power)
Source: Jamie Taylor 2008
or
![Page 27: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/27.jpg)
6
11
J. Hals: Power take-off systems for wave energy converters
Emulating a linear PTO force- time series from the Pelamis device
Source: Henderson., 2006
12
J. Hals: Power take-off systems for wave energy converters
Direct-coupled electric generators
Linear permanent-magnet generator, flat or tubularDemand for high force gives big machinesNon-linear force characteristic, but is easily controlledSimple; few moving componentsElectrical energy is storage a challenge
Source: Danielsson et al., 2008
![Page 28: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/28.jpg)
7
13
J. Hals: Power take-off systems for wave energy converters
Source: Danielsson et al., 2
008
Sour
ce:
Prad
o, 2
006
14
J. Hals: Power take-off systems for wave energy converters
Half a wave cycle of linear generator operation
Source: Polinder et al., 2004
Efficiency(from mechanical to grid)
![Page 29: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/29.jpg)
8
15
J. Hals: Power take-off systems for wave energy converters
Source: Neumann et al., 2006
14:30 14:35 14:400
50
100
150
200
Time
Con
verte
d po
wer
[kW
]
Source: Henderson, 2006
Air turbine, Pico plant
Hydraulic PTO, Pelamis
Direct-coupled generator, AWS
16
J. Hals: Power take-off systems for wave energy converters
Properties compared
SmallerLargerLargerSize (tendency)
Good (gasaccumulators)
DifficultModerate(shaft+flywheel)
Energy storage
Large forceLarge velocityLarge velocityForce or velocitypreference
HighLowHighNumber of components
0.5-0.8 (?)0.8-0.90.35-0.6Efficiency (average)
HydraulicsLinear generatorsAir turbines
![Page 30: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/30.jpg)
9
17
J. Hals: Power take-off systems for wave energy converters
So what is the best choise?
Depends onconceptfuture developments in each technologyend use (electricity or other)need for energy storage
![Page 31: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/31.jpg)
1MARINTEK
Wave and wind power seminar at CeSOSMay 27 2008
Power production in a wave energy converter. Effect of controls and operational constraints
Karl E. Kaasen, MARINTEK
![Page 32: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/32.jpg)
2MARINTEK
Topics
Heaving buoyFrequency domain modellingLinear power take-offIdeal world power maximisationRegular waves vs. spectral wavesConstrained maximisation
![Page 33: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/33.jpg)
3MARINTEK
Vertically moving buoyCase studied
Z
Wamit panel model(50 % submergence)
Diameter: 3.5 mMass: 20 tonsHeight, top-bottom: 5.25 m
![Page 34: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/34.jpg)
4MARINTEK
PTO as feedback from measured vertical speed
-
FE
FC
H(ω)
G(ω)
w
FE
FC
Theoretically optimal feedback:
G(ω) = 1/H(ω)*
(* = complex conjugation)
PTO dynamics
Buoy vertical velocity
Excitation forcefrom waves
Controlforce
Buoy dynamics
![Page 35: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/35.jpg)
5MARINTEK
Electrical equivalent (simpler and more intuitive)
E
I Z+
U
ZL
U = E - Z·I
load
˜ Internal impedance
E ~ FeU ~ FCI ~ u
Optimal load: ZL = Z*
![Page 36: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/36.jpg)
6MARINTEK
Power from a buoy in waves(J. Falnes)
21 1 12 2 2
21 12 2
(Available forcefor power generation)
Re{ } Re{ }
cos
exp( ), exp( )
, ,
e
e
e
e
e
e e F u
u F
F F Zu
P Fu F u Z u
F u R u
F F j u u j
Z R jX R B X A
γ
ϕ ϕ
γ ϕ ϕ
ω
= −
= = −
= −
= =
= −
= + = =(Z is the radiation ”impedance”)
![Page 37: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/37.jpg)
7MARINTEK
Power as a function of velocity amplitude (1 m wave amplitude, ω = 1.0 rad/s)
0 5 10 15 20 25 30-5
-4
-3
-2
-1
0
1
2
3x 10
5
Amplitude of velocity (m/s)
Pow
er (W
)
gamma = 0gamma = 45 deg
![Page 38: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/38.jpg)
8MARINTEK
Buoy in regular waves
10 20 30 40 50 60
-6
-4
-2
0
2
4
6
Phase = 0, no power
0 10 20 30 40 50 60
-6
-4
-2
0
2
4
6
Phase = pi/2, max power
![Page 39: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/39.jpg)
9MARINTEK
Power maximisation
2 2
maxcos cos
for8 2
e eF FP u
R Rγ γ
= =
2
for cos 1,8 2e e
MAXF F
P uR R
γ= = =
Maximisation with respect to velocity amplitude, u:
Maximisation with respect to u and phase angle difference, γ:
![Page 40: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/40.jpg)
10MARINTEK
Max power PMAX as function of frequency
Hypothetical (no constraints) for 3.5 m Ø buoy. 1 m wave amplitude
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2104
105
106
107
108
Frequency (rad/s)
Pow
er (
W)
![Page 41: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/41.jpg)
11MARINTEK
Optimum amplitudes of velocity and position(but violating premise of linearity)
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2100
101
102
103
104
Frequency (rad/s)
Velocity amplitude (m/s)Position amplitude (m)
Draught
![Page 42: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/42.jpg)
12MARINTEK
Added mass and damping at various draughts
67 % draught 50 % draught
33 % draught 15 % draught
![Page 43: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/43.jpg)
13MARINTEK
Excitation force at various draughts
0 5 10 15 20 25 300
20
40
60
80
100
Period T (s)
Hea
ve fo
rce
F 3 (k
N)
One egg alone
0 5 10 15 20 25 300
5
10
15
20
25
Period T (s)
Hea
ve P
hase
(deg
)
One egg alone
Draught 67 %Draught 50 %Draught 33 %Draught 15 %
Draught 67 %Draught 50 %Draught 33 %Draught 15 %
![Page 44: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/44.jpg)
14MARINTEK
Added mass and damping at various draughts
0 5 10 15 20 25 304
6
8
10
Period T (s)
Adde
d m
ass
Hea
ve A
33 (t
onn) One egg alone
0 5 10 15 20 25 300
2
4
6
8
Period T (s)
Dam
ping
Hea
ve B
33 (k
N/(m
/s))
Draught 67 %Draught 50 %Draught 33 %Draught 15 %
Draught 67 %Draught 50 %Draught 33 %Draught 15 %
![Page 45: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/45.jpg)
15MARINTEK
0 0.5 1 1.5 2 2.50
0.5
1
1.5
2
2.5
3 x 104
Frequency (rad/s)
Mass, added mass, total mass
kg
Total massAdded massDry mass
(50 % draught)
![Page 46: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/46.jpg)
16MARINTEK
Power absorption in spectral seas.How to choose controller characteristics?
0 0.5 1 1.5 2 2.5 30
0.5
1
1.5Jonswap spectrum, Hs=2.75, Tp=6.25, gamma=3.3
Frequency (rad/s)
![Page 47: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/47.jpg)
17MARINTEK
Load control
zgzgzgF pvaC ++=
ωωγ
ωγω
ωγ
∀≈−≈−≈−
≈≈+
+
≠==
,0)(:,:controlconjugateComplex
0)(::control(reactive)Resonance
0)(:0,0:controlPassive
2
kgmg
gmgk
gg
aa
ppa
p
ppa
![Page 48: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/48.jpg)
18MARINTEK
Constraints
Constraint on control force:
sigma_FC ≤ 50 kN (sigma = standard deviation)
Constraint on buoy motion:
sigma_z ≤ 0.5 m (absolute)or
sigma_zr ≤ 0.5 m (relative, zr = z – η)
![Page 49: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/49.jpg)
19MARINTEK
Ga [kN/(m/s2) ]
Gv
[kN
/(m/s
)]
Pow er as function of contro ller gains
0 20 40 60 80 100 1200
10
20
30
40
50
60
70
80
90
100
0
5
10
15
20
25
30
35
40
45
50
std X= 0,5 m
std Fc = 50 kN
3.5 m buoy, 20 t
Hs = 2.75 mTp = 6.25 s
Unconstrainedmax = 57 kW
Constrained max = 20 kW
Constrained optimum
Unconstrained optimum
![Page 50: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/50.jpg)
20MARINTEK
Results – constraint on force and absolute motion
Wave: Hs = 2.75 m, Tp = 6.25 s, gamma = 3.3Energy transport [kW/m] : 20.6Buoy diameter [m] : 3.5
Constrained optimum:Power output [kW] : 20.4Velocity gain, gv [kN/(m/s)] : 79Acceleration gain, ga [kN/(m/s^2)] : 53Standard deviation of motion [m] : 0.50Standard dev. of rel. motion [m] : 0.77Standard dev. of control force [kN]: 49.3
Unconstrained optimum:Power output [kW] : 56.6Velocity gain, gv [kN/(m/s)] : 7Acceleration gain, ga [kN/(m/s^2)] : 67Standard deviation of motion [m] : 2.83Standard dev. of rel. motion [m] : 2.89Standard dev. of control force [kN]: 194.
![Page 51: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/51.jpg)
21MARINTEK
Results - constraint on force and relative motion
Wave: Hs = 2.75 m, Tp = 6.25 s, gamma = 3.3Energy transport density [kW/m] : 20.6Buoy diameter [m] : 3.5
Constrained optimum:Power output [kW] : 18.7Velocity gain, gv [kN/(m/s)] : 32Acceleration gain, ga [kN/(m/s^2)] : 14Standard deviation of motion [m] : 0.69Standard dev. of rel. motion [m] : 0.50Standard dev. of control force [kN]: 27.5
Unconstrained optimum:Power output [kW] : 56.6Velocity gain, gv [kN/(m/s)] : 7Acceleration gain, ga [kN/(m/s^2)] : 67Standard deviation of motion [m] : 2.83Standard dev. of rel. motion [m] : 2.89Standard dev. of control force [kN]: 194.
![Page 52: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/52.jpg)
22MARINTEK
Frequency response of velocity – unconstr. optimum
0 0.5 1 1.5 2 2.50
2
4
6
8Amplitude response of velocity
(1/s
)
0 0.5 1 1.5 2 2.5-100
-50
0
50
100Phase response of velocity
Frequency (rad/s)
Deg
rees
![Page 53: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/53.jpg)
23MARINTEK
Velocity responseConstraint on abs. motion: sigma_z = 0.50 m
0 0.5 1 1.5 2 2.50
0.5
1Amplitude response of velocity
(1/s
)
0 0.5 1 1.5 2 2.5-50
0
50
100Phase response of velocity
Frequency (rad/s)
Deg
rees
(sigma_zr = 0.77 m)
![Page 54: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/54.jpg)
24MARINTEK
Velocity responseConstraint on rel. motion: sigma_zr =0.50 m
0 0.5 1 1.5 2 2.50
0.5
1
1.5Amplitude response of velocity
(1/s
)
0 0.5 1 1.5 2 2.5-50
0
50
100Phase response of velocity
Frequency (rad/s)
Deg
rees
(sigma_z = 0.69 m)
![Page 55: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/55.jpg)
1
1
Wind induced power – basic principles of power take-off
and equipment
Ole Gunnar DahlhaugDepartment of energy and process engineering
NTNU
2
Different types of wind turbines
• Drag-type turbines– Persian windmill– Chinese wind wheel– Saviounus
• Lift-type turbines– VAWT, Vertical Axis Wind Turbine
• Darrieus– HAWT, Horizontal Axis Wind Turbine
• The Danish concept• American multiblade• Grumman windstream
![Page 56: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/56.jpg)
2
3
Drag-type turbines
The Persian windmill
The Chinese wind wheel
Savonious
4
Drag-type turbines
Ref: www.ifb.uni-stuttgart.de/~doerner/edesignphil.html
![Page 57: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/57.jpg)
3
5
Lift-type turbinesVAWT, Darrieus
6
Lift-type turbinesVAWT, Darrieus
![Page 58: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/58.jpg)
4
7
Ref: www.ifb.uni-stuttgart.de/~doerner/edesignphil.html
8
Lift-type turbinesHAWT, American Multiblade
![Page 59: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/59.jpg)
5
9
Lift-type turbinesHAWT, Grumman Windstream
10
Lift-type turbinesHAWT, The Danish Concept
• The blades upwind the rotor• Constant speed on the rotor• Power output limitation
– Stall control
• Brakes– Mechanical– Aerodynamic
![Page 60: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/60.jpg)
6
11
SPEED n 20 17 13 5 – 15 3 – 10 rpm
HE
IGH
T [M
]
Development of HAWT
12
Onshore Wind Turbines
![Page 61: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/61.jpg)
7
13
Offshore Wind Turbines
14
Offshore Floating Wind Turbines
SWAY HYWIND
![Page 62: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/62.jpg)
8
15
Wind power and energy
• Power output from wind turbines:
• Energy production from wind turbines:
ηρ ⋅⋅⋅= AcPower2
3
Energy Power Time= ⋅
C
A
16
Energy flux for wind turbines
ηρ ⋅⋅⋅= AcP2
3
Recommended literature: Wind Turbine Technology, David A. Spera, ISBN no. 0-7918-1205-7
Where:P = Power [W]ρ = Density [kg/m3]c = Velocity [m/s]A = Area [m2]η = Efficiency [ - ]
![Page 63: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/63.jpg)
9
17
Global Installed wind power
Source: www.gwec.net
18
![Page 64: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/64.jpg)
10
19
Source: www.gwec.net
Installed wind power
20
Wind power capacity global forecast
Source: www.gwec.net
![Page 65: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/65.jpg)
11
21 Wind Power in Norwayper 1st January 2006
• Energy goal for 2010: 3 TWh
• Wind farms in operation:– Number of wind farms: 13– Number of wind mills: 165– Installed power: ca. 320 MW– Energy production: ca. 900 GWh
• Planned wind farms (License is given, but not built)– Number of wind farms: 15– Number of wind mills: 439– Installed power: 1214 MW– Energy production: 3866 GWh
• Planned wind farms (Applied for License)– Number of wind farms: 36– Number of wind mills: 1444– Installed power: 4496 MW
Hitra
22
![Page 66: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/66.jpg)
12
23
HAWTHorisontal-Axis Wind Turbines
SMØLA
24
HAWTMain Components
• Foundation• Tower• Nacelle• Hub• Turbine blades
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 67: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/67.jpg)
13
25
Towers
Guyed Pole Tower
Lattice tower Tubular steel towers,
Concrete tower
26
Tower designs
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 68: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/68.jpg)
14
27
Nacelle and Yaw system
Ref. www.windpower.org
28
Yaw system
Ref. www.windpower.org
![Page 69: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/69.jpg)
15
29
Nacelle
30
Nacelle
![Page 70: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/70.jpg)
16
31
Nacelle Design
Ref. Wind Power Plants, R.Gasch, J.Twele
32
Nacelle Drive Trains
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 71: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/71.jpg)
17
33
VESTAS V903 MW
108 TONS
34
![Page 72: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/72.jpg)
18
35
36
![Page 73: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/73.jpg)
19
37
Multibrid M5000 Power output: 5 MW
Diameter: 116 m.
Turbine speed: 5,9 -14,8 rpm
Masses:
Blade: 16.500 kg
Hub: 60.100 kg
Nacelle: 199.300 kg
38
(tons)
![Page 74: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/74.jpg)
20
39 Hydraulic transmission - 5 MW
P
M G
P = Hydraulic pump (Assumed weight 20 ton)
M = Variable displacement motor 8 x A4VSO1000
G = Generator placed at the bottom of the wind turbine
Weights in ton
40
Hub design
![Page 75: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/75.jpg)
21
41
Hub design
Ref. Wind Power Plants, R.Gasch, J.Twele
42
Hub design
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 76: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/76.jpg)
22
43 Blade Design
Ref. Wind Power Plants, R.Gasch, J.Twele
44
Design at different TSR
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 77: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/77.jpg)
23
45
46
Energy Flux in the wind
AreacP ⋅⋅=2
3
ρ
Where:P = Power [W]ρ = Density [kg/m3]c = Velocity [m/s]
![Page 78: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/78.jpg)
24
47
Wind velocity, power and energy
TimePowerEnergy ⋅=
0
100
200
300
400
500
600
700
800
900
1000
0 5 10 15 20 25
Velocity [m/s]
Tim
e [h
/yea
r]
0
100
200
300
400
500
600
0 5 10 15 20 25
Velocity [m/s]
Ener
gy [k
Wh/
m2 ]
ηρ ⋅⋅⋅= AcPower2
3
48
Power output
0
1 000
2 000
3 000
4 000
5 000
6 000
7 000
8 000
9 000
10 000
0 5 10 15 20 25
Wind Speed [m/s]
Pow
er [k
W]
Wind Power
Turbine Power
![Page 79: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/79.jpg)
25
49
Aerodynamic brakes
Ref. Wind Power Plants, R.Gasch, J.Twele
50
Stall control
Ref. Wind Power Plants, R.Gasch, J.Twele
![Page 80: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/80.jpg)
26
51
Turbine blade pitch system
Ref. Wind Power Plants, R.Gasch, J.Twele
52
Turbine blade pitch system
![Page 81: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/81.jpg)
27
53
54
Links
• www.windpower.org/• www.ewea.org• www.nve.no• www.hydro.com/no/our_business/oil_energy/new_energ
y/wind/index.html• www.statkraft.no/pub/vindkraft/index.asp• www.gwec.net• http://ec.europa.eu/research/energy/nn/nn_rt/nn_rt_wind
/article_1101_en.htm
![Page 82: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/82.jpg)
28
55
• Wind Power Plants, Fundamentals, Design Construction and Operation
– R. gasch, J. Twele, ISBN no. 1-902916-38-7
• Wind Turbine Technology– David A. Spera, ISBN no. 0-7918-1205-7
• Guidelines for design of Wind Turbines– DNV, RISØ, ISBN no. 87-550-2870-5
• Wind Energy Handbook– T. Burton, D. Sharpe, N. Jenkins, E. Bossanyi, ISBN no. 0-471-48997-2
• Aerodynamics of Wind Turbines– Martin O. L. Hansen, ISBN no. 1-902916-06-9
Recommended literature
![Page 83: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/83.jpg)
1
Introduction by
Torgeir Moan, CeSOS
Session 2Dynamic analysis of floating systems
subjected to wave- and wind loads
CeSOS, May 27. 2008
2
Wind turbine concepts
tower
bladehub
nacelle
Wave energy converter
Rotor/flywheel for smoothing energy
Basic systems
3
Data, methods,criteria
Fabrication & Operation
data
Layout/Scantlings
Design for- serviceability &- producability- safety
Fabrication &installation- Fabrication plan -- Inspection/repair
Operation- Operation plan
Inspection/monitoring/ repair / maintenance
Removal and reuse
Reassessment
Life Cycle Phases of Marine Structures
Example: Spar wind turbine
+ Installation ofthe mooring system
4
Guidelines and standardsOffshore wind turbineso The IEC 61400-3 “Safety requirements for offshore wind turbines”,
International Electrotechnical Commission (2006). • Emphasis is given to the determination of load assumptions• Should be used in conjunction with the appropriate IEC/ISO standards
o Design of offshore wind turbines structures, Det Norske Veritas (DNV) (2004). • Consistent design philosophy in compliance with onshore wind turbine design • Strongly integrated with latest best practice offshore technology
o Guideline for the Certification of Offshore Wind Turbines, Germanischer Lloyd WindEnergie (2005). • Reflects state of the art offshore wind engineering• Covers all necessary requirements to support structures, blades and machinery.
Wave energy converters- No specific standard- Implement codes, standards and guidelines for offshore engineering(Det Norske Veritas: “Guideline on the design and operation of wave energyconverters”, Carbon Trust (2005)).
![Page 84: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/84.jpg)
5 Design criteria for safety (with focus on structural failure modes)
System design checkAccidental collapse (ALS)- Ultimate capacity1) of
damaged structure with “credible” damage
Component design check depending on residual system strength andaccess for inspection
Fatigue (FLS)- Failure of welded joints
due to repetitive loads
Different for bottom – supported, or buoyant structures.Component design check
Ultimate (ULS)-Overall “rigid body”
stability- Ultimate strength of
structure, mooring or possible foundation
RemarksPhysical appearance offailure mode
Limit states
Collapsedcylinder
Totqlcollapse
Fatigue -fracture
6 Analysis for different criteria- different limit states (SLS, ULS, ALS, FLS)
Extreme displacement/stress, stress history in thestructure, mooring system, power off-take equipment
- assumed ”shut down” condition of moveable parts…(wind turbine, wave energy off-take system..)
- different fault conditions- account of automatic control
• SLS criteria : deflection criteria for turbine blade distance from tower• ULS criteria : different type of wave conditions for WEC,
combined wind and wavephenomena for WiEC- intact structure, including intentional ”shut down ”
conditionse.g. buoys of FO’s WEC in fixed upper or mean position
idle wind turbine• ALS criteria : fault conditions during power production and idle wind turbine• FLS criteria : combined long term wave and wind conditions
7
1330 Dynamic modelling of multi-body structures – for wave power generation by Reza Taghipour, CeSOS 1400 Dynamic modelling of wind turbines under combined wave and wind loading by Dr. Rune Yttervik, StatoilHydro 1430 Coffee break 1445 Mooring of floating plants by Dr. Zhen Gao, CeSOS 1515 Discussion: Challenges for the future. 1600 End of the day
Dynamic analysis of floating systems subjected to wave- and wind loads
![Page 85: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/85.jpg)
Wave and Wind Power Seminar @ CeSOSMay 27. 2008
Dynamic Modelling of Multi-Body Structures for wave power
generation
R. Taghipour, A. Arswendy, T. Moan
CeSOS
![Page 86: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/86.jpg)
Need among the state-of-the-art!
• Loads and response (wave-induced)
• Floating structure complexity
• Interactions
• Layouts
• Performance
![Page 87: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/87.jpg)
Objective and Scope
Structural response analysis
Objectives: First order wave-induced motions and internal loads, displacements and stressesPower output
![Page 88: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/88.jpg)
Case study: The FO3 WEC
![Page 89: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/89.jpg)
Hydrodynamic Analysis
![Page 90: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/90.jpg)
Motion AnalysisOriginal Modes of Motion:• Surge (platform and buoys )• Sway (platform and buoys )• Platform heave• Roll with sliding (platform and buoys)• Pitch with sliding (platform and buoys)• Yaw (platform and buoys)• Buoy #1~21 heave
i.e. total d.o.f.s = 27
Available Approaches:• Standard Approach: number of d.o.f.s to solve=132• Generalized Modes: number of d.o.f.s to solve=27
![Page 91: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/91.jpg)
Assumptions
• First order hydrodynamic loads
• Power absorption mechanism model
![Page 92: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/92.jpg)
Dynamic equilibrium:The equations of motions
![Page 93: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/93.jpg)
Motions of each componentFollowing-Seas Waves (B=0)
Results show symmetrical properties resembling the physical problem symmetry.
Strong influence on motions from the power absorption mechanism.
![Page 94: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/94.jpg)
Motions of each componentOblique-Seas Waves (B=45)
Results show symmetrical properties resembling the physical problem symmetry.
![Page 95: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/95.jpg)
Wave EnvironmentJONSWAP-Mitsuyasu Spectrum
![Page 96: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/96.jpg)
Power Absorption Statistics
Following-Seas Wave Condition Oblique-Seas Wave Condition
Wave is attenuated along its direction.Practically no power output from the buoys in the down-stream.Absorbed power was found independent of mean wave direction.The pattern of absorbed-power changes with wave direction.
![Page 97: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/97.jpg)
Structural Analysis
![Page 98: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/98.jpg)
The Interfacing Procedure
![Page 99: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/99.jpg)
Validation for simplified case by comparison with analytical solution
![Page 100: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/100.jpg)
Different Mesh Configurations
![Page 101: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/101.jpg)
Stress along the column
![Page 102: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/102.jpg)
FRF of the Axial Load and Bending Moment
![Page 103: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/103.jpg)
FEA of FO3
![Page 104: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/104.jpg)
Consistent hydrodynamic and structural models
![Page 105: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/105.jpg)
Verification@ B=0
ΣFa=FPTO
ΣRF=0
The unbalance was found in practice to be 1.3% of the inertia force.
![Page 106: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/106.jpg)
Comparative Study: Column-Deck Loads (Monochrome Following-Seas Wave B=0)
Axial Force-Amplitude Axial Force-Phase
Bending Moment-Amplitude (N.m.)
-1.0E+2
-6.0E+1
-2.0E+1
2.0E+1
6.0E+1
1.0E+2
1.4E+2
SC1 SC2 SC3 SC4
Columns Only FO3 WEC
0.0E+0
5.0E+4
1.0E+5
1.5E+5
2.0E+5
2.5E+5
3.0E+5
3.5E+5
SC1 SC2 SC3 SC4
Columns Only FO3 WEC
-1.8E+2
-1.4E+2
-9.0E+1
-4.5E+1
0.0E+0
4.5E+1
9.0E+1
1.4E+2
1.8E+2
SC1 SC2 SC3 SC4
Column Only FO3 WEC
Bending Moment-Phase (N.m.)
0.0E+0
5.0E+8
1.0E+9
1.5E+9
2.0E+9
2.5E+9
3.0E+9
SC1 SC2 SC3 SC4
Columns Only FO3 WEC
![Page 107: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/107.jpg)
Comparative Study: Column-Deck Loads (Multiple Following-Seas Wave Range B=0)
0.E+00
5.E+04
1.E+05
2.E+05
2.E+05
3.E+05
3.E+05
4.E+05
0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3wave frequency (rad/sec)
FO3 WEC SC1FO3 WEC SC2Columns Only SC1Columns Only SC2
0.E+00
5.E+08
1.E+09
2.E+09
2.E+09
3.E+09
3.E+09
0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3wave frequency (rad/sec)
Full Platform-SC1Full Platform-SC2Only Platform-SC1Only Platform-SC2
![Page 108: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/108.jpg)
Guide-Deck LoadsMonochrome Following-Seas Wave B=0)
Axial Force Bending Moment
• Significant load decrease along the direction of wave progression
0.0E+0
1.0E+3
2.0E+3
3.0E+3
4.0E+3
5.0E+3
6.0E+3
7.0E+3
8.0E+3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Guide Axial Force: Amplitude
-300
-250
-200
-150
-100
-50
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Guide Axial Force: Phase
0.0E+0
2.0E+7
4.0E+7
6.0E+7
8.0E+7
1.0E+8
1.2E+8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Guide Bending Moment: Amplitude
-200
20406080
100120140160180
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Guide Bending Moment: Phase
![Page 109: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/109.jpg)
Guide-Deck Loads(Multiple Following-Seas Wave Range)
Loads decrease as one moves towards the guides down streamWave is attenuated.Interaction/diffraction effects become dominant at the short wave range.
![Page 110: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/110.jpg)
FRF in Oblique Seas Waves
Column-DeckBending Moment
Column-DeckAxial Force
![Page 111: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/111.jpg)
1
Dynamic modelling of floating wind turbine under combined wind and wave loading
Wave and wind power seminar at CeSOS, Trondheim, 27.05.2008.
Rune Yttervik
2
Contents of presentation• Introduction / motivation
• Floating wind turbine – excitation mechanisms
• Floating wind turbine – damping mechanisms
• Floating wind turbine – dynamical properties
• H2SR analysis tool
• HYWIND Demo
– Purpose
– Main properties
• Issues of particular interest
![Page 112: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/112.jpg)
3
Introduction / motivation• Dynamic response is determined by excitation
mechanisms, damping mechanisms and dynamic properties.
• Excitation mechanisms
– Ocean waves
– Wind field
– Ocean currents
• Damping mechanisms
– Mechanical damping
– Hydrodynamic damping
– ‘Electrical/aerodynamic damping’ (power production)
• Dynamic properties
– Mass
• Structural mass
• Added mass
– Stiffness
• Elastic stiffness (beams)
• Geometric stiffness (mooring system)
• Hydrostatic stiffness
4
Floating wind turbine – excitation mechanisms• Ocean waves
– Stochastic, irregular, linear, directional spreading.
• Wind field
– Vertical shear.
– Stochastic atmospheric turbulence
– Mean speed and direction.
• Ocean currents
– Surface currents, variable speed and direction.
• Gravity
• Forces from interacting structure components
– Blade/tower
• Cyclic load on the cylinder structure
• Cyclic load on the rotor
• Steady load on the cylinder structure
• Steady load on the rotor
![Page 113: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/113.jpg)
5
Wind field simulation• Three velocity components
• 3D random wind field
• Homogenous in space
• Spectral tensor
• Wave number & separation vector (as opposed to frequency and time difference)
• Duration : 10 min. !!
rrkrk diRijij exp)(8
1)( 3
References :
Jakob Mann, ‘Wind field simulation’, Prob. Engng. Mech. Vol. 13, No. 4, pp. 269-282, 1998.
A. G. Davenport, ‘Wind structure and wind climate’, Safety of Structures under Dynamic Loading, Volume 1, pp. 209-237, Norwegian Institute of Technology, 1977.
Davenport (1977)
6
Floating wind turbine – damping mechanisms• Passive damping mechanisms
– Mechanical damping
– Hydrodynamic damping
• Hull
• Mooring system
• Active damping mechanisms
– ‘Electrical/aerodynamic damping’ (power production)
![Page 114: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/114.jpg)
7
Effect of different control strategies
0 200 400 600 800 1000 1200 1400 1600 1800-5
0
5
10
15
20
time [s]
tow
er to
p m
otio
n [m
]
CCADSCCWO
0 0.05 0.1 0.15 0.2 0.250
5
10
15
20
25
30
35
frequency [Hz]
sqrt(
Sf)
Tower Top Motion
CCADSCCWO
Active Damping Control with
Sea State Compensation
Active Damping Control with
Low Pass Filtering of Nacelle Velocity
Wind 17 m/s
Tint 10%
Hs 5m
Tp 12s0 200 400 600 800 1000 1200 1400 1600 1800
-5
0
5
10
15
20
time [s]
tow
er to
p m
otio
n [m
]
CCADC LP3WO
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.20
5
10
15
20
25
30
35
frequency [Hz]sq
rt(S
f)
Tower Top Motion
CCADC LP3WO
8
Floating wind turbine – dynamic properties• Mass
– Structural mass
• Hull
• Tower
• Mooring system
• Nacelle
• Rotor blades
– Added mass
• Hull
• Mooring system
• Stiffness
– Elastic stiffness
• Hull
• Tower
• Rotor blades
– Geometric stiffness
• Mooring system
– Hydrostatic stiffness
• Ballasting, stability
![Page 115: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/115.jpg)
9
Floating wind turbine – stiffness propertiesElastic stiffness (cylinder structure & rotor blades) Geometric stiffness
(mooring system)
Hydrostatic stiffness
Ballasting
Waterplane areaPitch
Heave
Roll
Surge
Yaw
Sway
10
Floating wind turbine – dynamics summarized
SurgePitchHeave Yaw
Wave
Wind
1st, 2nd and 3rd elastic bending
1p 2p 3p
17)( rpm :n
[Hz] 60np1
![Page 116: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/116.jpg)
11
Computer tool for analysis of dynamic response• HAWC2SIMORIFLEX (H2SR).
• HAWC2
– Wind field model
– Finite element structural modelling
– Aerodynamic modelling (Blade Element Momentum Method)
• SIMO
– Data exchange (position, velocity, acceleration, force).
• RIFLEX
– Wave field model
– Current field model
– Finite element structural modelling
– Hydrodynamic modelling (Morison)
HAWC2
RIFLEX
SIMO
12
Visualisation of computer simulation
Hs 11 m,
Tp 14 sek,
Uw 18.9 m/s
![Page 117: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/117.jpg)
13
HYWIND Demo - purpose
• Document proof of the HYWIND concept.
• Develop a basis for commercial attractive solutions for future floating offshore wind farms.
• Verify and optimize the concept, by further develop cost efficient technical solutions for fabrication, assembly and installation methods during project execution.
14
HYWIND Demo - concept• Main data
– WTG: 2,3 MW
– Turbine weight: 138 tons
– Rotor diameter: 82,4 m
– Draft: 100 m
– Displacement: 5300 m3
– Diameter at water line: 6 m
– Diam. submerged body: 8,3 m
• Characteristics
– Steel tower
– Steel substructure
– 3 point mooring system
– Dynamic pitch regulation
– Completed at inshore site
– Towed upright to field
– Designed for extreme North Sea conditions
![Page 118: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/118.jpg)
15
A common detailed test programme shall be carried out including:
• Testing of various control strategies of the turbine and investigate consequences for motions, fatigue loads, WTG performance and power production
• Testing of response to various failure modes
• Check of sensitivity to oblique wind and tilt
• Testing of alternative access systems
HYWIND Demo – test program
16
Issues of particular interest – future work• Definition of design codes to be used.
• Statistics of wind and waves, joint probability.
• Selection of load cases.
– ULS
– ALS
– FLS
– PLS?
• Analysis tool with full coupling of aerodynamic and hydrodynamic loading and response.
• Access offshore.
• Control algorithms for optimal combinations of power production, structural capacity and cost.
![Page 119: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/119.jpg)
1
CeSO
S
Mooring System for Wave Energy
Converter
Zhen GaoJu Fan
Torgeir Moan
May 27, 2008
![Page 120: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/120.jpg)
2
CeSO
S
Contents
• The FO3 Wave Energy Converter• Objectives• Mooring analysis method• Hydrodynamic analysis (survival condition)• Comparison of the time- and frequency-domain results• Sensitivity study• Conclusions• Future work
![Page 121: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/121.jpg)
3
CeSO
S
The FO3 Wave Energy Converter (WEC)
• The FO3 WEC model
![Page 122: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/122.jpg)
4
CeSO
S
Objectives
• Investigate possible mooring systems– Components: polyester lines, buoys– Configuration: multiple WECs
• Study the effect of mooring system on WEC motions– Surge, sway and yaw– Heave, roll and pitch
• Mooring system analysis for multiple WECs in a farm
![Page 123: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/123.jpg)
5
CeSO
S
Special considerations on WEC mooring systems (1)• Mooring system types
• Design considerations on WEC mooring systems– Shallow-water (70m)– Allowable vertical loads– Effect on vertical vessel motions– Farm design
a) b) c)Catenary Taut-line Taut-line with buoys
![Page 124: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/124.jpg)
6
CeSO
S
Buoys
Special considerations on WEC mooring systems (2)• Farm design considerations• Standardized mooring components • Accessibility• Connection/Disconn.• Stability• Mooring design
on the boundary• Inspection plan• Failure analysis
Buoys
Clump weightBuoy
Clump weight
Buoy
Taut-line system Taut-line system with interior catenary lines
![Page 125: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/125.jpg)
7
CeSO
S
Mooring analysis method
• Outline of mooring system analysis
• Frequency-domain analysis (uncoupled) • Time-domain analysis (coupled)
Wind
Wave
Current
OriginalPosition
MeanPosition
Dynamic Analysis (WF+LF)
Static Analysis
![Page 126: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/126.jpg)
8
CeSO
S
• Survival condition– Hs=10.4m, Tp=14.4s, P-M; Uwind=29m/s; Ucurrent=2m/s– Env. Dir. 0 and 45
• Position of eggs:
Hydrodynamic analysis of the WEC
Operational condition
Survival condition
Still water
Deck
![Page 127: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/127.jpg)
9
CeSO
S
Natural periods of WEC motions
• Hydrodynamic model (underwater part), WADAM
• Natural periods (sec)
(wave periods: 5-25 sec)
5510Roll (pitch)
136.2Heave
DeckStill water
![Page 128: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/128.jpg)
10
CeSO
S
RAO of WEC motions
• Direct calculation by single-body analysis• Re-generated from multi-body analysis using generalized
modes, considering motion constraint between the platform and the eggs (Still water case)
• When the eggs are assumed to move freely along the guides.
Circular frequency (rad/s)0.0 0.5 1.0 1.5 2.0 2.5
RA
O -
Hea
ve (m
/m)
0.0
0.5
1.0
1.5
2.0
2.5SB_DeckSB_StillWaterGM_FreeGM_StillWater
Circular frequency (rad/s)0.0 0.5 1.0 1.5 2.0 2.5
RA
O -
Pitc
h (d
eg/m
)
0
1
2
3
4
5SB_DeckSB_StillWaterGM_FreeGM_StillWater
Heave RAO Pitch RAO
![Page 129: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/129.jpg)
11
CeSO
S
The effect of viscous damping on RAO
Heave RAO Pitch RAO
• Viscous damping due to collars• 10%, 30% of critical damping
Circular frequency (rad/s)0.0 0.5 1.0 1.5 2.0 2.5
RA
O -
Hea
ve (m
/m)
0.0
0.5
1.0
1.5
2.0
2.50% of critical damping10% of critical damping30% of critical damping
Circular frequency (rad/s)0.0 0.5 1.0 1.5 2.0 2.5
RA
O -
Pitc
h (d
eg/m
)
0
1
2
3
4
50% of critical damping10% of critical damping30% of critical damping
![Page 130: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/130.jpg)
12
CeSO
S
• Mooring system configuration– Four-line system, S1=57.2m, S2=40m– Polyester, D=125mm, Breaking strength=4811kN
D=150mm, Breaking strength=6927kN– Buoy, B=1000kN
Time-domain mooring analysis (1)
Mooring system layout
Dir. 0Dir. 45
Largest tension36 m
![Page 131: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/131.jpg)
13
CeSO
S
Time-domain mooring analysis (2)
• SIMO+RIFLEX– Coupled analysis (vessel motion + mooring line tension)– Nonlinear analysis
• Mean offset:
6.7-0.6013.7
(FD: 13.5)Dir. 45
11.7-0.3017.1
(FD: 15.5)Dir. 0
Pitch (deg)Heave (m)Surge (m)
![Page 132: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/132.jpg)
14
CeSO
S
Time-domain mooring analysis (3)
• Time series of the tension in the mostly loaded line:– Dir. 0:
Buoyancy– Dir. 45:
Line stretching
Dir. 0
Dir. 45
![Page 133: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/133.jpg)
15
CeSO
S
Time-domain mooring analysis (4)• Spectral analysis (Dir. 0)
Surge
Heave Pitch
Tension
55 5555
55
2M
M AT
K Kπ
+=
+
ω ω
ωω
![Page 134: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/134.jpg)
16
CeSO
S
Comparison of the T-D and F-D results
• Dynamic vessel motions: T-D (F-D)
• Mooring line tension at fairlead: T-D (F-D)
7.0 (6.0)2.3 (1.7)2.8 (3.8)0.8 (1.1)8.2 (6.9)1.6 (1.7)Dir. 45
10.6 (8.9)3.1 (2.5)2.9 (3.8)1.0 (1.1)11.6 (9.5)2.5 (2.4)Dir. 0
1-h ext.Std.1-h ext.Std.1-h ext.Std.
Pitch (deg)Heave (m)Surge (m)
4097 (3274)872 (/)759 (725)Dir. 45
1045 (850)521 (/)471 (453)Dir. 0
1-h ext.Std.Mean
Tension (kN)
![Page 135: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/135.jpg)
17
CeSO
S
Sensitivity study• Buoyancy; Length of mooring line; Damping ratio in heave and
pitch; Position of fairlead• Horizontal length of anchor position: Dir. 0 (Dir. 45)
54 m 90 m 126 m
1004(4455)
36.4(25.8)
1200(5857)
34.3(24.2)
2658(8326)
35.2 (24.4)
B=500kN
900(1877)
24.8(19.9)
920(2124)
23.9(19.0)
850(3273)
25.0(20.4)
B=1000kN
1-h ext.tension (kN)
1-h ext.surge (m)
1-h ext.tension (kN)
1-h ext.surge (m)
1-h ext.tension (kN)
1-h ext.surge (m)
126 m90 m54 mFD results
![Page 136: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/136.jpg)
18
CeSO
S
Conclusions
• Hydrodynamic analysis of the WEC in survival conditions.– Eggs are locked at the still water level– Eggs are locked under the deck
• Natural periods of the heave, roll and pitch motions are close to the important wave periods.
• Viscous damping due to collars needs to be considered in the calculation of motion RAO.
• Mooring line tension in the proposed configuration is mainly induced by surge (or sway) motion. Heave, roll and pitch motions are not significantly affected by mooring system.
• The frequency-domain method is practically acceptable compared with the time-domain simulations.
![Page 137: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/137.jpg)
19
CeSO
S
Future work
Buoys
Buoys
Clump weightBuoy
Clump weight
Buoy
Taut-line system Taut-line system with interior catenary lines
• Time-domain Multi-WEC mooring analysis
![Page 138: Wave and wind power seminar - cesos.ntnu.no · 1 Introduction by Torgeir Moan, CeSOS Wave and wind power seminar with a focus on the use of floating facilities CeSOS, May 27. 2008](https://reader034.vdocuments.mx/reader034/viewer/2022042022/5e7928369a7d64397b1a6e0d/html5/thumbnails/138.jpg)
20
CeSO
S
Thank you !