High Reliability Solutions & Innovative Concepts for Offshore Wind Turbines

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63rd IEA Topical Expert Meeting

HIGH RELIABILITY SOLUTIONS AND INNOVATIVE

CONCEPTS FOR OFFSHORE WIND TURBINES

September 21-22 2010

SINTEF Energy Research, Trondheim, Norway

Organized by: CENER


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Disclaimer:

Please note that these proceedings may only be redistributed to persons in countries participating inthe IEA RD&D Task 11.

The reason is that the participating countries are paying for this work and are expecting that theresults of their efforts stay within this group of countries.

The documentation can be distributed to the following countries: Canada, Denmark, EuropeanCommission Finland Germany Ireland Italy Japan Korea Mexico the Netherlands Norway Spain


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International Energy Agency

Implement Agreement for Co-operation in the

Research, Development and Deployment of Wind

Turbine Systems: IEA Wind

The IEA international collaboration on energy technology and RD&D is organized under

the legal structure of Implementing Agreements, in which Governments, or their delegated

agents, participate as Contracting Parties and undertake Tasks identified in specific Annexes.

The IEAs Wind Implementing Agreement began in 1977, and is now called the

Implementing Agreement for Co-operation in the Research, Development, and Deployment of

Wind Energy Systems (IEA Wind). At present, 24 contracting parties from 20 countries, the

European Commission, and the European Wind Energy Association (EWEA) participate in

IEA Wind. Australia, Austria, Canada, Denmark, the European Commission, EWEA, Finland,

Germany, Greece, Ireland, Italy (two contracting parties), Japan, the Republic of Korea,

Mexico, the Netherlands, Norway (two contracting parties), Portugal, Spain, Sweden,

Switzerland, the United Kingdom, and the United States are now members.

The development and maturing of wind energy technology over the past 30 years has been

facilitated through vigorous national programs of research, development, demonstration, and

financial incentives. In this process, IEA Wind has played a role by providing a flexible

framework for cost-effective joint research projects and information exchange.

The mission of the IEA Wind Agreement continues to be to encourage and support thetechnological development and global deployment of wind energy technology. To do this, the

contracting parties exchange information on their continuing and planned activities and

participate in IEA Wind Tasks regarding cooperative research, development, and

demonstration of wind systems.

Task 11 of the IEA Wind Agreement Base Technology Information Exchange has the


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IEA Wind TASK 11: BASE TECHNOLOGY INFORMATION

EXCHANGE

The objective of this Task is to promote disseminating knowledge through cooperative

activities and information exchange on R&D topics of common interest. Four meetings on

different topics are arranged every year, gathering active researchers and experts. These

cooperative activities have been part of the Agreement since 1978.

Two Subtasks

The task includes two subtasks. The

objective of the first subtask is to develop

recommended practices for wind turbine

testing and evaluation by assembling an

Experts Group for each topic needing

recommended practices. For example, theExperts Group on wind speed

measurements published the document

titled Wind Speed Measurement and Use

of Cup Anemometry. A document dealing

with Sodar measurements are presently

Documentation

Since these activities were initiated in

1978, more than 60 volumes of

proceedings have been published. In the

series of Recommended Practices 11

documents were published and five of

these have revised editions.

All documents produced under Task 11

and published by the Operating Agent are

available to citizens of member countries

participating in this Task.


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COUNTRIES PRESENTLY PARTICIPATING IN THE TASK 11

COUNTRY INSTITUTION

Canada National Resources Canada

Denmark Ris National Laboratory - DTU

European Commission European Commission

Finland Technical Research Centre of Finland - VTT Energy

Germany Bundesministerium fr Unwelt , Naturschutz und Reaktorsicherheit -BMU

Ireland Sustainable Energy Ireland - SEI

Italy Ricerca sul Sistema Energetico - RSE S.p.A.

Japan National Institute of Advanced Industrial Science and Technology AIST

Republic of Korea POHANG University of Science and Technology - POSTECH

Mexico Instituto de Investigaciones Electricas - IEE

Netherlands SenterNovem

Norway The Norwegian Water Resources and Energy Directorate - NVE

SpainCentro de Investigaciones Energticas, Medioambientales y Tecnolgicas

CIEMAT


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CONTENTS

Page

INTRODUCTORY NOTE

a) BackgroundIX

b) Techniques..X

c) Topics to be addressedXI

d) Expected outcomes..XI

e) AgendaXII

PRESENTATIONS

1.Presentation of Introductory Note

Mr. John O. Tande SINTEF 01

1.Review of the OC3 IEA Wind Task 23 & Plans for OC4 under Task 30

Jason Jonkman, National Renewable Energy Laboratoy (NREL), USA..09

2.Findings and Prospects in Research on Support Structures and Foundations

in GIGAWIND alpha ventusJan Dubois, Leibniz Univ. of Hannover, Germany ...33

3. DeepCWind Floating Offshore Wind Project in the U.S.

Amy Robertson National Wind Technology Center (NREL) USA 49


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Anand Natarajan. Ris DTU. Denmark ...87

7. IDERMAR METEO: an innovative solution for offshore wind assesment.

Ral Guanche Garca. IH Cantabria. Spain 97

8. ZEFIR Test StationRajai Aghabi Rivas. IREC. Spain 111

9. The status of research and technology development on offshore wind energy in Japan

Chuichi Arakawa.Kyoto University, Japan................121

10. Research and Development of a Hybrid-spar for Floating Offshore Wind Turbine

Tomoaki Utsunomiya, Civil and Earth Resources Engineering Dep, Kyoto Univ. Japan ..133

11. Influence of Waves to Wind Misalignment to Dynamic Characteristics...."

Yoshida Shigeo. Fuji Heavy Industries. Japan 163

12. Integrated Dynamic Response Analysis of Spar-Type Wind Turbines with Catenary and

Taut Mooring.

Madjid Karimirad.Torgeir Moan. NTNU. Norway 169

13. Innovative Concepts for Offshore Wind Installations.

Peter Jamieson. Univ Stratchclyde UK .179

14. WindFlip, a transportation vessel for offshore floating wind turbines.

Torbjrn Mannsker. Marintek. Norway ..201


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European Commission .235

SUMMARY

a) Participants

b) Discussion

c) Future actions under the umbrella of IEA Wind


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INTRODUCTORY NOTE

Prepared by John Olav Tande

a) Background

Targets are set for a massive installation of offshore wind farms. In Europe alone plans suggest 40 GW

by 2020 and 150 GW by 2030 as viable. The development is ongoing, but in an early stage. Only about

2 GW of offshore wind farms have so far been installed, and all relatively close to shore at shallow

waters using what can be called on-shore wind technology. The exceptions are the Beatrice wind farm

installed at 46 m water depth using jacket sub-structures, the Alpha Ventus wind farm demonstratingjackets and tripods for foundation, and the floating wind turbine concepts, HyWind and BlueH. New

concepts are under development, e.g. SWAY, WindFloat and WindSea.

The experience so far indicates that technical challenges related to offshore installation, operation,

maintenance and repairs have been underestimated, though are now being addressed by the industry and

applied research.

Bottom-fixed wind farms, and mainly at shallow waters, are expected to dominate the near term

development, whereas industry-scale deployment of deep offshore (floating) wind farms are expected

after 2020.

A joint challenge in offshore wind is costs. The very ambitious targets for development of offshore wind

farms are only likely to be realized provided significant cost reductions. This can be achieved through

incremental improvements, e.g. gaining cost reductions through more efficient mass-fabrication and

installation procedures, reduction of risks and contingencies through experience and better engineering

tools, improved quality in critical parts and more cost-efficient operation and maintenance.


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b) Techniques

Improving the reliability of offshore wind turbines is paramount to the success of offshore wind

energy in the future. The larger the machine and further away from the coast, the larger the economic

loss for non-operation and associated maintenance. Vintage wind turbines often have the same gearbox

for their entire working lives. Modern wind turbines are much larger and optimised by weight and

efficiency. They need a number of major overhauls during their lifetimes to ensure efficient operation,

as does any conventional power generation plant. Wind turbines are currently designed in such a way

that the exchange of main components or sub assemblies is difficult. More efficient and newer drive

train concepts are needed to bring turbine reliability up to the required level. A more modular build up

of drive trains with more built in redundancy could help faster, cheaper and more efficient turbine

maintenance. The need for extremely reliable machines offshore can also be an extra driver for the

reliability of onshore machines.

Innovative concepts, such as variable speed, direct-drive offshore wind turbines are currently

emerging, with the aim of limiting the number of moving parts and lowering maintenance costs, as

gearboxes are expensive to replace offshore. A multi-pole gearless machine also operates at lower drive

train speeds and thus creates less stress on components. A main challenge for these concepts is to reduce

the weight on top of the tower, in order to optimise the use of material and limit the transport and

installation costs. So far, gearless machines have been heavier and more expensive to produce than their

geared equivalent. Lighter gearless technology is now being tested onshore.

Larger machines (5 to 10 MW), specifically designed for offshore could bring benefits in terms of

economies of scale by placing fewer larger machines on fewer foundations, or increasing the wind

farms power output. For example, economies of scale could also be realised by increasing the lifetime

to 30 years, provided it does not negatively affect the design.

Concepts such as two-bladed downwind turbines could emerge in the medium term. Two-bladed


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volumes required. Therefore the offshore wind industry must take urgent steps to rectify this situation.

In addition, the supply of substructures should not been seen as independent from their transport and

installation as an integrated approach is taken, taking into account unique site conditions and the

location of the wind farm.

Substructures represent a significant proportion of offshore development costs. In the case described

by Papalexandrou , the foundation represents 25% (5 MW turbine) to 34% (2 MW turbine) of

investment costs in 25m water depth. Thus, novel sub-structure designs and/or improved manufacturing

processes that reduce costs will be critical to improving the economics of offshore developments.

c) Topics to be addressed

The main objective is to hold a meeting to discuss and gather information on:

Wind Characteristics Measurement for Offshore Assessment

New Technological Solutions for WT

New Technical Solutions for Support Structures

The participants were encouraged to prepare presentations relevant to these objectives.

d) Expected outcomes

One of the goals of the meeting will be to gather the existing knowledge on the subject and come up

with suggestions / recommendations on how to proceed for future developments. The proceedings

document will contain:

Presentations by participants

Compilation of the most recent information on the topic

Main conclusions of the discussion session.

D fi iti f IEA Wi d RD&D f t l i thi t i


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e)Agenda

Tuesday, September 21st

09:00 Registration. Collection of presentations and final Agenda

09:25 Introduction by Host

President Sverre Aam, SINTEF Energy Research

09:40 Introduction by AIE Task 11 Operating Agent. Recognition of Participants

Mr.Felix Avia, Operating Agent Task 11 IEAWind R&D

10:00 Presentation of Introductory Note

Mr. John O. Tande SINTEF

10:30 Coffee Break

11:10 Review of the OC3 Project under IEA Wind Task 23 & Plans for OC4

under Task 30. Jason Jonkman, National Renewable Energy Laboratoy

(NREL), USA

11:35 Findings and Prospects in Research on Support Structures and

Foundations in GIGAWIND alpha ventus. Jan Dubois, Leibniz University of

Hannover, Germany

12:00 Lunch

13:00 DeepCWind Floating Offshore Wind Project in the U.S.

Amy Robertson. National Wind Technology Center, NREL, USA

13:25 SAEMar Project. Anchoring Systems for Renewable Marine Energies

Offshore Platforms. Ral Rodrguez Arias, Centro Tecnolgico de

Componentes, CTC, Santander .Spain


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15:05 Coffee Break

15:30 ZEFIR Test Station.Rajai Aghabi Rivas. IREC. Spain

15:55 The status of research and technology development on offshore wind energy

in Japan.Chuichi Arakawa,Kyoto University, Japan

16:20 Research and Development of a Hybrid-spar for Floating Offshore Wind

Turbine. Tomoaki Utsunomiya, Department of Civil and Earth Resources

Engineering Kyoto University, Japan

16:45 Influences of Wave to Wind Misalignment to Dynamic Characteristics and

Fatigue Loads on Spar-type Floating Offshore Wind Turbine.

Yoshida Shig, Fuji Heavy Industries. Japan

17:10 Adjourn

19.00 Informal dinner

Wednesday, September 22nd

09:00 Welcome

09:15 Integrated Dynamic Response Analysis of Spar-Type Wind Turbines with

Catenary and Taut Mooring.

Madjid Karimirad.Torgeir Moan. NTNU.Norway

09:40 Innovative Concepts for Offshore Wind Installations.

Peter Jamieson. Univ. Stratchclyde. UK

10:05 WindFlip, a transportation vessel for offshore floating wind turbines.

Torbjrn Mannsker. Marintek. Norway.

10:20 Research activities on bottom-supported wind turbines.


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11:40 EU-funded activities under FP7.

Thierry Langlois dEstaintot. New and Renewable Energy Sources. Directorate-

General Research. European Commission

12:05 Lunch

13:00 Discussion and Summary of Meeting

14:00 Technical Tour to the Ocean Basin Laboratory at MARINTEK.

16:00 End of the meeting


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PRESENTATIONS


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HIGH RELIABILITY SOLUTIONS

AND INNOVATIVE CONCEPTS

John Olav Giver Tande

Director NOWITECH

Introduction to IEA Wind TEM #63

Trondheim, 21-22 September 2010

1

Senior Research Scientist

SINTEF Energy Research

[email protected]

www.nowitech.no

NOWITECH in brief

Objective:Pre-competitive research laying a foundation for industrial value creationand cost-effective offshore wind farms. Emphasis on deep sea (+30 m).

R&D partners: SINTEF, IFE, NTNU + associates: Ris DTU (DK), NREL & MIT(US), Fraunhofer IWES (DE), Universit y of Strathclyde (UK), TU Delft (NL)

Industry partners: Statkraft, Statoil, Vestavind Kraft, Dong Energy, Lyse,Statnett, Aker Solut ions , SmartMotor , NTE, DNV, Vestas, Fugro Oceanor,Devold AMT, TrnderEnergi, EDF + associates: Innovation Norway, Enova,NORWEA, NVE, Energy Norway, Navitas Network

TEM 63 "High Reliability Solutions and Innovative Concepts for Offshore Wind Turbines"


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NOWITECH vision large scale deployment of deep sea offshore wind turbines

an internationally leading research communit y on offshore windtechnology enabling industry partners to be in the forefront.

Means and main ambitions

Combine wind technology know-how with offshore and energy industryexperience to enhance development of o ffshore w ind.

Establish a recruitment and educational programme that provides fo rhighly qualified staff at Master and PhD level for serving the industry.

Build strong relations wi th selected top international research partners.

Facilitate active involvement by industry partners to ensure relevanceand efficient communication and utilization of results.

3

Support to industry is through pre-competitive research commercialdevelopment w ill come as a result and be run in separate projects.

Act ively pursue opportuni ties to increase R&D act ivi ty on crit ical issues.

Strong motivation for of fshore wind R&D

Huge potential

Offshore wind is vital forbattling climate change,

KarmyKarmyKarmy

Offshore 2030: 150 GW*

Offshore 2020: 40 GW* HyWind(floating, 200m)

(jacket, 46m)

security of supply

Development at an early

stage; less than 2% of the

l b l i d it i

Offshore 2009: ~2 GW


TEM 63 "Hi h R li bilit S l ti d I ti C t f Off h Wi d T bi "


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Lots of options to improve bottom-fixed support structures

Mono-pile dominates themarket for shallow waters

Jackets and tripods are-

depths (+30 m)

Various new concepts arebeing developed byindustry, incl. concrete sub-structures (Vici Ventus)

Lots of room forimprovements throughintegrated design, incl.control actions to reduce

5

Design should also consideralternative ways for

installation.

Graphics: copy from Haiyan Long , PhD student NTNU, 2009

Many exciting floating concepts

(2009, 2,3 MW)




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The HyWind demo in operation since Sept. 2009

Turbine power 2,3 MW

Turbine weight 138 tons

Nacelle height 65 m

Rotor diameter 82,4 m

Water depth 150700 m

Displacement 5300 tons

Moorin 3 lines

7

D @ water line 6 m

D submerged 8,3 m

Data from Statoil

One big advantage of floaters: relatively easy installation!




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Is HyWind stable? Yes; according to

Simulations and Test in Ocean Basin Lab (2005)

20

)

-5

0

5

10

wertopdisplacemen

t(

9

100 150 200 250 300

-15

-

Time (s)

To With stabilizer

Without stabilizer

2.5

3

changle[-] controller tuned

controller not tuned

Measurements of HyWind operating at 2,3 MW

1

1.5

2

eantowerpit

TEM 63 High Reliability Solutions and Innovative Concepts for Offshore Wind Turbines



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Will floaters be economic?

Wind

turbine

O&MWind

turbine

O&M

Sub-structure

Grid

Sub-structure

Grid

HyWind 2,3 MW floater: 1300 tons of s teel;simple struc ture, suitable for mass

production; quick installation; amounts of

steel can be reduced through

optimization

11

p a entus ac et: tons o

steel; complex structure & installation;

what wi ll the steel weight be at 50 m waterdepth?

Tower top weight is cr itical for keeping the cost down

TEM 63 High Reliability Solutions and Innovative Concepts for Offshore Wind Turbines



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An optimized grid is a key for eff icient in tegration

Hydropower

withstora e

Statnett vision (2009)Main challenges

Many possible grid configurations

New market solutions are required

New technology (HVDC VSC, mult i-

SK

1,2,3

NorNed

SK 4

NORD.LINK / NorGer

Ekofisk

Wind farms

i

terminal, hybrid HVDC/HVAC, .. )

Cost, Reliability and Security of Supply

1080

10100

10120

10140

leconfigurations

13

Wind and hydro:

a win-win combination

0 5 10 15 20 25 3010

0

1020

1040

10

Number of nodes

Numb

erofcab

Why bother with all th is new, when there are

plenty of challenges in need for urgent attention?

Need for both; long term R&Dare the answer to be prepared

for the ur encies of tomorrow

New solutions should be robust

Systems for remote monitoring,

state estimation and control

g y p



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NOWERI: a platform for R&D (expected 2012)

~225 kW

15

Rounding up

Remarkable results are already achieved by industry and

R&D institutes on offshore wind

Technology still in an early phase Big potential provided

The goal of this meeting is to address high reliability



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Review of the OC3 ProjectUnder IEA Wind Task 23

& Plans for OC4 Under Task 30IEA Wind Task 11 TEM #63

September 21-22, 2010

Trondheim, Norway

Jason Jonkman, Ph.D.Senior Engineer, NREL

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

The Offshore Code Comparison Collaboration (OC3)

project operated under Subtask 2 of IEA Wind Task23

The OC3 & OC4 Projects



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IEA Wind Task 11 TEM #63 3 National Renewable Energy Laboratory

OWTs are designed using aero-hydro-servo-elastic codes

The codes must be verified to assess their accuracy

OC3/OC4 Background

Discuss modeling strategies

Develop suite of benchmark models & simulations

Run simulations & process results

Compare & discuss resultsActivities

OC3/OC4 Activities & Objectives



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OC3 Participants & Codes

3Dfloat

ADAMS-AeroDyn-HydroDyn

ADAMS-AeroDyn-WaveLoads

ADCoS-Offshore

ADCoS-Offshore-ASAS

ANSYS-WaveLoads BHawC

Bladed

Bladed Multibody

DeepC

FAST-AeroDyn-HydroDyn

FAST-AeroDyn-NASTRAN

FLEX5

FLEX5-Poseidon

HAWC HAWC2

SESAM

SIMPACK-AeroDyn

Simo

All inputs are predefined:

NREL 5-MW wind turbine, including control system Variety of support structures

Wind & wave datasets

A stepwise procedure is applied:

Load cases selected to test different model featuresApproac

h

OC3/OC4 Approach & Phases



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Load Cases

1.X Full-System Eigenanalysis

Full-system flexibility

Elastic response only

Compared natural frequencies &

damping ratios2.X Rigid

Rigid turbine

Aerodynamics without hydro:

Steady & turbulent winds

Hydrodynamics without aero:

Regular & irregular waves

3.X Onshore Wind Turbine

Flexible tower, drivetrain, & rotor

Rigid substructure

Aero-servo-elastics without hydro:

Steady & turbulent winds

4.X Inverted Pendulum

Flexible support structure

Rigid tower top

Hydro-elastics without aero:

Regular & irregular waves

5.X Full-System Dynamics

Full-system flexibility

Full aero-hydro-servo-elastics:

Steady winds with regular waves

Turbulent winds with irregular waves

Output Parameters



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OC3 Results

1 conference paper per phasepublished/presented:

Phase I: Torque, 2007

Phase II: EOW, 2007

Phase III: AIAA, 2009

Phase IV: EWEC, 2010

Final report reviewing allphases in publication,including updated results

submitted since originallypublished

Journal article in progress

Jump in complexity from monopile to

tripod: Multiple members

Statically indeterminate (loads influencedby relative deflection of members)

Nonaxisymmetric

OC3 Phase III Results: Tripod



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Jump in complexity from fixed to floating:

Low-frequency modes (influence onaerodynamic damping & stability)

Large platform motions (coupling with turbine)

Complicated shapes (radiation & diffraction) Moorings (new component)

Key findings (may only apply to thisspar):

Radiation damping is negligible; so, codes thatapply Morisons equation are adequate

Quasi-static mooring models provide adequatereactions for global response analysis;dynamic mooring models, however, result inmore line excitation at higher frequencies

Turbine structural flexibilities had an effect onturbine loads, but little effect on spar motions

Spar Concept bySIWAY

OC3 Phase IV Results: Spar Buoy

OC3-Hywind Spar Buoy

Title: Verification of simulation codes for ajacket-supported fixed-bottom WT

Coordinator: Fraunhofer-IWES

Rambll has kindly agreed to make theUpWind WP4 reference jacket available to

OC4 Phase I Plans: Jacket



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Title: Verification of simulation codes fora WT on a floating semi-submersible

Coordinator: NREL

OC4 participants will choose betweenPrinciple Power Inc.s (PPI) WindFloat &DeepCwind generic semi-submersibles:

PPI WindFloat is a patented commercialsystem with first full-scale installationscheduled for late 2011

DeepCwind is a generic publically availabledesign to be wave-tank tested at 1/50th scale

in early 2011

Code-to-code comparison results will bepublished in a conference paper in 2012

Spar Concept by SWAY

OC4 Phase II Plans: Semi-submersible

WindFloat(Image: D. Roddier, PPI)

OC4 focuses on code-to-code verification;

code-to-experiment validation also needed OC4 participants dont comprise all experts

needed to develop field validation plan

Separate meeting proposed for 2011

OC4 Code Validation Experts Meeting



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OC3/OC4 aims to verify OWT dynamics

codes

Benchmark models & simulations established

Simulations test a variety of OWT types &model features

Code-to-code comparisons have agreed well

Differences caused by variations in:

Model fidelity

Aero-, hydro-, & structural-dynamic theories

Model discretization

Numerical problems

User error

Many code errors have been resolved

Engineers equipped with modeling experience

Spar Concept by SWAYSemi-submersibleConcept

Summary

Thank You for Your Attention



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IEA Task 23 Organizational Structure

OC3 Coordination & Meetings

E-mail coordination

Net-meetings held every 1-2months

Physical meetings held 1-2



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Countries will pay 5,000/year to participate

9 countries assumed to join, for an annual budget of 45000/yr

No limit on the number of participants, but each participant

should be approved by the countrys ExCo representative Meeting hosts will donate costs voluntarily

Spar Concept by SWAY

OC4 Funding & Cost

Operating Agent Responsibilities Funding (3 yr)

NREL WP2 CoordinationExpert Meeting Coord.

ReportingProject Management

Website

95000

Fraunhofer-IWES WP1 CoordinationReporting

40000

TOTAL 135000

OC4 Project Schedule

ID Tas k Na me

1 ExCo Approval of Annex 302 Receive Commitment Letters3 Receive Funds4 Jacket Code Comparison - Work Package 15 Publish Paper or Report on Jacket6 Establish Floating Design Concept7 Floating Platform - Work Pakage 2

11/9

2/1

3/31

1/29

O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O

2010 2011 2012 2013



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OC4 Organizational Structure

Interested countries must joinTask 30

Committed:

Germany, USA

Declined:

EC, EWEA, Switzerland

Country Commitments



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Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute Battelle

OC3: Benchmark Exercise of

Aero-elastic Offshore WindTurbine Codes

J A Nichols and T R Camp, Garrad Hassan and Partners Ltd.

J Jonkman and S Butterfield, NRELT Larsen and Anders Hansen, Ris

J Azcona, A Martinez and X Munduate, CENERF Vorpahl and S Kleinhansl, CWMT

M Kohlmeier, T Kossel and C Bker, Leibniz University of HannoverD Kaufer, SWE University of Stuttgart

Phase III: Offshore Tripod

Significant jump incomplexity frommonopile substructure.



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Modelling wave loads

Importance of modelling the structure near thesea surface in detail

Without a fine discretisation, sharp jumps areseen in load signals

-4000.0000

-3500.0000

-3000.0000

-2500.0000

-2000.0000

-1500.0000

-1000.0000

-500.0000

0.0000

0 5 10 15 20 25 30 35

Time [s]

ShearForce[kNm]

Upwind leg axial shearforce (coarsediscretisation)

Upwind leg axial shearforce (fine

discretisation)

A

xialForce

(kN)

Modelling overlapping members

It is important to takeaccount of theoverlapping regionswhen structuremembers join at nodes



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Modelling shear deflection

Bernoulli-Euler theoryonly considers purebending of a beam.

One side is compressedwhile the other isstretched.

In real beams, there issome shear deformationof the material.

This becomes importantonce relative deflection ofjoined members becomes

xM

P( )MPl

EI

lx 6)4(

12

2

++=

l

212lGA

EI

S

=

Modelling shear deflection



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Results - Eigenanalysis

0.0000

0.5000

1.0000

1.5000

2.0000

2.5000

3.0000

1stT

owerFore-Aft

1stT

owerSide

-to-Side

1stD

rivetrain

Torsion

1stBlad

eCollectiveFlap

1stBlad

eAsymmetric

Flap

wise

Pitch

1stBlad

eAsymmetric

Flap

wise

Yaw

1stBlad

eAsymmetric

Edgewise

Pitch

1stBlad

eAsymmetric

Edgewise

Yaw

2ndTowerF

ore-Aft

2ndTowerSide

-to-Side

2ndBladeCollective

Flap

2ndBladeAsymmetric

Flap

wise

Pitch

2ndBladeAsymmetric

Flap

wise

Yaw

CENER FASTNASTRAN Natural Frequency (Hz)

CENER Bladed Natural Frequency (Hz)

CWMT ADCoS Natural Frequency (Hz)

GH Bladed Natural Frequency (Hz)

GH Bladed (Timoshenko) Natural Frequency (Hz)

LUH WaveLoadsANSYS Natural Frequency (Hz)

Risoe HAWC2 Natural Frequency (Hz)

Risoe HAWC2_BE Natural Frequency (Hz)

SWE FLEX5Poseidon Natural Frequency (Hz)

Results Output Locations

1

2

3

4

5

6

1

2

3

4

5

6



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Results bending moments due to wave loads

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0

5000

10000

5 10 15

Simulation Time (s)

BendingMoment(kNm

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0

5 10 15

Simulation Time (s )

BendingMoment(kNm)

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0

2000

4000

6000

8000

5 10 15

Simulation Time (s)

BendingMoment(kNm)

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0

5 10 15

Simulation Time (s)

BendingMoment(kNm

-1500

-1450

-1400

-1350

-1300

-1250

-1200

5 10 15

Simulation Time (s)

BendingMoment(kNm)

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

5 10 15

Simulation Time (s)

BendingMoment(kNm)

1 2

3 4

5 6

-15000

-10000

-5000

0

5000

10000

5 10 15

Simulation Time (s)

BendingMoment(kNm

-700

-600

-500

-400

-300

-200

-100

0

5 10 15

Simulation Time (s )

BendingMoment(kNm)

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

5 10 15

Simulation Time (s)

BendingMoment(kNm)

-3000

-2500

-2000

-1500

-1000

-500

0

5 10 15

Simulation Time (s)

BendingMoment(kNm

-1500

-1450

-1400

-1350

-1300

-1250

-1200

5 10 15

Simulation Time (s)

BendingMoment(kNm)

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

5 10 15

Simulation Time (s)

BendingMoment(kNm)

1 2

3 4

5 6

Results shear forces due to wave loads

-100

-50

0

50

100

150

5 10 15

Simulation Time (s)

ShearForc

e(kN)

-200

-150

-100

-50

050

100

150

200

250

300

5 10 15

Simulation Time (s)

ShearForc

e(kN)

40

60

80

100

ce(kN)

20

30

40

50

ce(kN)

1 2

3 4

-100

-50

0

50

100

150

5 10 15

Simulation Time (s)

ShearForc

e(kN)

-200

-150

-100

-50

050

100

150

200

250

300

5 10 15

Simulation Time (s)

ShearForc

e(kN)

40

60

80

100

ce(kN)

20

30

40

50

ce(kN)

1 2

3 4



43/266


Results axial forces due to wave loads

-7103

-7102

-7102

-7101

-7101

-7100

-7100

-7099

-7099

5 10 15

Simulation Time (s)

AxialForce(kN)

-4500

-4000

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

5 10 15

Simulation Time (s)

A

xialForce(kN

-1200

-1000

-800

-600

-400

-200

0

200

400

600

5 10 15

Simulation Time (s)

A

xialForce(kN

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

500

1000

5 10 15

Simulation Time (s)

AxialForce(kN

-6000

-5000

-4000

-3000

-2000

-1000

0

5 10 15

Simulation Time (s)

AxialForce(kN

-7250

-7240

-7230

-7220

-7210

-7200

-7190

-7180

-7170

-7160

5 10 15

Simulation Time (s)

AxialForce(kN)

1 2

3 4

5

6

-7103

-7102

-7102

-7101

-7101

-7100

-7100

-7099

-7099

5 10 15

Simulation Time (s)

AxialForce(kN)

-4500

-4000

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

5 10 15

Simulation Time (s)

A

xialForce(kN

-1200

-1000

-800

-600

-400

-200

0

200

400

600

5 10 15

Simulation Time (s)

A

xialForce(kN

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

500

1000

5 10 15

Simulation Time (s)

AxialForce(kN

-6000

-5000

-4000

-3000

-2000

-1000

0

5 10 15

Simulation Time (s)

AxialForce(kN

-7250

-7240

-7230

-7220

-7210

-7200

-7190

-7180

-7170

-7160

5 10 15

Simulation Time (s)

AxialForce(kN)

1 2

3 4

5

6

Motion of the dynamic support structure

-0.035

-0.030

-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

5 10 15

Tower

Top

Displacement

(m



44/266

Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute Battelle

IEA Wind Task 23 OC3:Phase IV Results Regarding Floating Wind Turbine Modeling

Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by the Alliance for Sustainable Energy, LLC

Floating Challenges & Phase IV Model

Low frequency modes:

Influence aerodynamic damping & stability

Large platform motions:

Coupling with turbine

Complicated shape:

Radiation & diffractionChallenge

s



45/266


Aero-Hydro-Servo-Elastic Capabilities

FAST Bladed ADAMS HAWC2 3Dfloat Simo SESAM / DeepC

Code Developer

NREL GH MSC + NREL

+ LUH

Ris-DTU IFE-UMB MARINTEK DNV

OC3 Participant

NREL + POSTECH GH NREL + LUH Ris-DTU IFE-UMB MARINTEK Acciona + NTNU

Aerodynamics

( BEM or GDW )

+ DS

( BEM or GDW )

+ DS

( BEM or GDW )

+ DS

( BEM or GDW )

+ DS

( BEM or GDW ) BEM None

Hydrodynamics

Airy++ ME,

Airy + PF + ME

( Airy+or Stream )

+ ME

Airy++ ME,

Airy + PF + ME

Airy + ME Airy + ME Airy + PF + ME Airy++ ME,

Airy + PF + ME

Control System (Servo)

DLL, UD, SM DLL DLL, UD DLL, UD, SM UD DLL None

Structural Dynamics (Elastic)

Turbine: FEMP+( Modal / MBS ),

Moorings: QSCE

Turbine: FEMP+( Modal / MBS ),

Moorings: UDFD

Turbine: MBS,Moorings: QSCE,

UDFD

Turbine: MBS / FEM,Moorings: UDFD

Turbine: FEM,Moorings: FEM, UDFD


MBS


FEM

Airy+ Airy wave theory+) with free surface corrections

BEM blade-element / momentum

DLL external dynamic link library

DNV Det Norsk Veritas

DS dynamic stall

GDW generalized dynamic wakeFEM

P finite-element method

P) for mode preprocessing only

MBS multibody-dy namics formulation

ME Morisons equation

MSC MSC Software Corporation

PF l inear potential flow with radiation &diffraction

QSCE quasi-st atic catenary equations

SM interface to Simulinkwith MATLAB

UD implementat ion through user-defined

subroutine available

UDFD implementat ion through user-defined force-

displacement relationships

Phase IV Load Cases

LoadCase

Enabled DOFs Wind Conditions Wave Conditions Analysis Type

1.2 Platform, tower,drivetrain, blades

None: air density = 0 Still water Eigenanalysis

1.3 Platform, tower,drivetrain, blades

None: air density = 0 Still water Static equilibrium solution

1.4 Platform None: air density = 0 Still Water Free-decay test time series

4.1 Platform, tower None: air density = 0 Regular Airy: H= 6 m, T= 10 s Periodic time-series solution

4 2 Platform tower None: air density = 0 Irregular Airy: Hs = 6 m Tp = 10 s Time-series statistics DELs



46/266


Output Parameters (57 Total)

Rotor BladeLoads & Deflections

13 Outputs

Drivetrain & GeneratorLoads & Operation

7 Outputs

TowerLoads & Deflections

15 Outputs

EnvironmentWind & Waves4 Outputs

PlatformDisplacements6 Outputs

Mooring SystemFairlead & Anchor

Tensions & Angles12 Outputs

Output Parameters & Results Legend

Results Legend

Full-System Eigenanalysis



47/266


Free Decay

Free Decay in Platform Surge

Free Decay in Platform Pitch

Hydro-Elastic Responsewith Regular Waves



48/266


Hydro-Elastic Responsewith Irregular Waves

Aero-Hydro-Servo-Elastic Responsewith Regular Waves



49/266


Aero-Hydro-Servo-Elastic Responsewith Irregular Waves

Aero-Hydro-Servo-ElasticEffective RAOs



50/266


Close agreement was not achieved by all codes:

What was the reason?

The effective RAO load case was somewhat academic:

What response charateristic is more relevant? Alternative suggested by IF RAOs could be derived from irregular

time series & cross spectra between excitation & response

The stochastic response statistics & spectra are sensitive to

simulation length:

What length would be more appropriate?

How can we eliminate start-up transients from the comparisons?

Unresolved Issues of OC3 Phase IV

OC3-Hywind platform was considered as a rigid body; nohydro-elastic effects

OC3-Hywind platform is simple in shape; only a single member

Hydrodynamic radiation & diffraction was negligible in theOC3-Hywind spar buoy

Sea current was never considered

Limitations of OC3 Phase IV



51/266

FindingsFindings andand ProspectsProspects

in Research on Supportin Research on Support StructuresStructures andand

FoundationsFoundations in GIGAWINDin GIGAWIND alphaalphaventusventus

Raimund Rolfes1, P. Schaumann1, Jan Dubois1,T. Schlurmann1, L. Lohaus1, M. Achmus1, H. Huhn2

1) Leibniz Universitt Hannover2) Fraunhofer IWES

1. The alpha ventus Wind Farm

2. The GIGAWIND alpha ventus

Research Project within RAVE

3. Research Objectives

4. GIGAWIND alpha ventusin DetailWP1 - Load Modelling for WavesWP2 - Fatigue Resistance /

Nov 2009



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1st German offshore wind farm

12 x 5MW OWECs (Multibrid / REpower) Operator: DOTI

Distance from coast: 45 km

Water depth: 30m

Planning: since 2006

Installation: 2008 2009

Research: RAVE

alpha ventus

2nd installationphase 2009

About alpha ventus

Location



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Layout of alpha ventus

Multibrid M5000

REpower 5M

Met MastFINO 1

GIGAWIND project GIGAWIND project

Holistic design concept for offshore windturbine support structures

BMU project (Coordination: LUH)3 Mio.

member in

50 Mio.



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GIGAWIND alpha ventusConsortium

Franzius-Institutfr Wasserbau und

Ksteningenieurwesen

Cooperation Partners:

coordination

deputy coordination

associated project in: funded by:

Cost reduction of OWEC support

structures

lighter support structures

optimised design process

Comprehensive simulation and design

package

holistic design concept

Research Objectives

corrosionrate



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WP1 - Load Modelling for Waves

Large scale model tests

Impact loads of breaking waves

Waveloads of nonbreaking waves

Spatial and time-resolved pressuredistribution

Wave kinematics Validation

Computational fluid dynamics (CFD)

Calibration of numerical models

Analysis of impact loads

Probabilistic design concepts

Influence of sea state parameters

Source: Franzius-Institute for Hydraulic, Waterways and Coastal Engineering, Arndt Hildebrandt, 2010

Wave Loads

Large scale model tests:

Impact loads of breaking waves

Waveloads of nonbreaking waves Spatial and time-resolved pressure

distribution

Wave kinematics

Validation

Wave Loads



56/266

fixture and box

pile

sleeve

testedinlaboratory

anima

tionoffshore

box

Measurements on Grouted Jointsof real structures

Hybrid connections for Offshore-WEC Grouted Joints

WP 2 - Fatigue Resistance /Manufacturing Aspects

Source: Nick Lindschulte, Institute of Building Materials Science, 2010

18m

sea level

tripod

relative displacementbetween pile and sleeve

z

r

t

measuring box

standard inductivesensor

Measurement of manufactured

geometry

Implementation of filters

FE-analyses of imperfect structure

Assessment of fatigue resistance of

imperfect tubular welded joints

Influence of Manufacturing Aspects on Fatigue Assessment



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Transfer of electrochemical laboratory methodsonto offshore structures

Example: EP-coating on thin sheet for tin cans in 3% acetic acid

laboratory cell

proper coating weak coating

10-2

10-1

100

101

102

103

104

103

104

105

106

107

108

109

1010

1011

Impedance/Z/

/

c

m2

10-2

10-1

100

101

102

103

104

103

104

105

106

107

108

109

1010

1011

Impedance/Z/

/

c

m2

t = 0

t = 4d

t = 8d

t = 11d

t = 0

t = 4d

t = 8d

t = 11d

defect after 46 days

Corrosion Monitoring

WP3 - Corrosion Protection

Source: Fraunhofer IWES, Holger Huhn

Implementation and testing of sensor electrodes oncoated samples

2 weeks

6 months




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Field exposure test of sensorized and coated samples

WP3 - Corrosion Protection


Source: Fraunhofer IWES, Holger Huhn

High Performance Mortar for Corrosion Protection

By polymer modification of the HPM:

The freeze-thaw resistance can beincreased compared to a concrete for

Hydraulic Structures The spalling of the surface decreases

to a minimum (153 g/m)

Spalling of the concrete surfaces after several freeze-thaw-cycles

0

250

500

750

1000

1250

1500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

freeze-thaw-cycles

spalling[g/m]

reference

styrene-butadiene10,0%

styrene-butadiene20,0%

styrene-acrylate10,0%

styrene-acrylate20,0%



59/266

Example Reduction of stiffness in the upper sectionof the mast by dissolving 264 bolts: ~100%

Method Multi-parameter eigenvalue problem,scanning parameter

Detection Parameter of intact/defect system: 0,999 => 0,004

means reduction of stiffness of 99,6%.

Inverse load detection from measured structural responses

Early damage detection

Damage localisation (global, local)

Damage quantification

Damage curve over life time percomponent

Estimation of residual load capacityand residual life time

Serial, cost-efficient offshore application

Test of the monitoring system atan onshore-WT with girder mast

Sdwind S70 1,5MW

SHM

REpower5

M(

av)

WP4 - Load Monitoring Systems

Monitoring of an Offshore Support Structure (SHM):(foundation, tower and rotor blades)

Source: Institute of Structural Analysis, Johannes Reetz

TP5:Arne Stahlmann



60/266

WP5 - Scour Protection /Scour Monitoring

Research Activities on Scouring Phenomena

0, 3000

RW: d=2.5m, Hm=0.76m, Tm=5.48s

S/D1P: 0.823P: 1.13MC: 1.11 3P

1P

MC

Physical model tests (1:40 & 1:12)

Modeling of scours

Flow pattern and turbulences

Scouring processes at complex offshore

structures

Scour protection systems Calibration and validation of numerical

models

Computational fluid dynamics (CFD):

Simulation of scour depths and evolutions

Forecasting and dimensioning

Soil-structure interaction

Franzius-Institute (2010)

Franzius-Institute (2010)

Innovative Scour Protection Chains

Connected chains of concrete elements;

physical model tests (1:40 & 1:12)

Soil-Structure Interaction (FEM)

Investigations on the effect of scours on

the stiffness distribution, deflection lines

and secant rotations (right figure)

Scour Protection & Soil-Structure Interaction

Monopile: S: scour depth



61/266

Foundation system and loading

condition of monopile foundation

a) pile deflection lines

after N cycles

b) Accumulation rate of horizonatal

displacement at pile topStress distributions from the numerical analyses

WP6 - Soil Modelling

Source: Institute of Soil Mechanics and Foundation Engineering, Khalid Abdel-Rahman, Marina Mller

Investigation based on Cyclic triaxial test results FE simulations

Result: Performance of a monopile

under cyclic loads

Stiffness Degradation Method (SDM):Estimation of Monopile Deformationunder Cyclic Lateral Load

Validation of the Stiffness DegradationMethod (SDM)

SDM Characteristics:

Allows estimating the accumulatedpile deformation under cyclichorizontal loading

Combination of cyclic triaxial testresults and numerical simulations



62/266


Prediction of the Axial Pile Capacity

Predicting the shaft friction with CPT-based methods

Validated against a database

Just 6 pile tests are relevant for German Conditions

Pile diameter is almost less than 1.0 m

Over proportional arise of pile capacitywith increasing diameter


Source:InstituteofSoilMechanicsandFoundationEngineering,

Khalid

Abdel-Rahman,

MarinaMller

General structural modelinitial state based on construction data

Measurement datadynamic behaviour from system

identification (AR models)

Definition of validation

parameter

on the basis of sensitivity analysis

Validation process- optimisation algorithm, e. g. Newton iteration,

inverse eigenvalue problem (Natke)

GUI of the software Vali tooleigenfrequencies as

target values



63/266

WP8

FAST

ADAMS

Aerodynamic

loads

Aerodynamic

loads

Date Base Controller GUI / Visualization

AeroDyn

PoseidonWaveLoads ANSYS

Design- and Simulation Framework for Offshore Wind Turbines (DeSiO)

GIGAWIND alpha ventus -Tools

Poseidon/WaveLoadsAV4 alpha ventusAdams/WaveLoads/ AeroDynOC3 Tripod

WaveLoads OC3 Tripod

DeSiO OC3 Tripod

WP8 - Holistic Design Concept

Source: Institute for Steel Construction, Vsquez; Institute of Structural Analysis, Reil, Kohlmeier, 2010

Modelling

AeroDyn

WaveLoadsADAMS

FAST

DeSiO

Poseidon ANSYS

GIGAWIND alpha ventus - Tools

ControllerDate base Visualization

FALCOS



64/266

Multibody Dynamics Simulation

AeroDyn

WaveLoadsADAMS

FAST

DeSiO

Poseidon ANSYS



FALCOS

OC3 floating turbine

analysed in Adams

OC4 jacket structure

analysed in Adams

5MW NREL Baseline Turbinegenerated with FAST

Wave loading on floating

spar-buoy structuregenerated by WaveLoads

WP8 - Holistic Design Concept

Source: Institute for Steel Construction, Vsquez; Institute of Structural Analysis, Reil, Kohlmeier, 2010

OC4 jacketstructure

analysed inWaveLoads

FE-Modelling of Structural JointsFatigue assessments according to the

structural stress concept

Y-, Double-K, Tripod-Joint, and others

AeroDyn

WaveLoadsADAMS

FAST

DeSiO

Poseidon ANSYS



FALCOS



65/266

Conclusion

Methods for several aspects of the

design process for OWEC support

structures has been developed

Holistic design concept with an easyoperable design and simulation package

Validation of simulation models against

measurement data from the offshore test

field alpha ventus

Offshore test field alpha ventusin November 2009

OWEC support structures have to become

an cost efficient mass product!

Cost optimisation of support structuresdesigned for further offshore wind farms

Thank you for yourThank you for your

attention!attention!

www.gigawind.de

www.rave-offshore.de

www.alpha-ventus.de

This presentation is composed bycontributions from researchers ofGIGAWIND alpha ventus:

WP 1 Arndt HildebrandtWP 2 Nick Lindschulte

Malte GottschalkWP 3 Holger Huhn

Hannes WeickenWP 4 Johannes Reetz



66/266



67/266

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

DeepCWind Floating Offshore WindProject in the U.S.

Topical Expert Meeting#63

Amy Robertson

September 21, 2010

DeepCWind Project Maine, USA

New Technology Development

Initiative for floating windtechnology

Funding ~ $25M US Dollars

1/50th scale model testing

D

(>60 )



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NATIONAL RENEWABLE ENERGY LABORATORY

UMaine Test Site Timeline

This is a pilot project to evaluate feasibility and cost ofdeploying floating offshore wind turbines.

The primary objectives are to:

Validate coupled aeroelastic/hydrodynamic models for floatingoffshore wind turbines.



69/266


STEP 1: Scaled Model Testing

5

1/50th scale models willbe tested at a world classwave/wind facility

Models are based onNREL 5MW referenceturbine.

Model testing isscheduled for April 2011.

Generic Floating Platforms

Three generic platformdesigns have beenidentified for tanktesting.



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Validate/revise coupled aeroelastic/hydrodynamic models

7

Development ofnumerical models ofall three generic

designs. Data generatedfrom these tests willbe used to validateNRELs coupledaeroelastic/hydrodynamic

models.

Model Scaling

Offshore platforms are typically scaledusing Froude Number and geometricsimilarity:

Frm= Frf m= model

Lm= Lf f = full scale

Froude Number will not scale all parametersproperly, but maintains proper inertia scaling

Fr =C

2

gL

Froude Number:ratio of bodysinertia to

gravitational forces

C= wave celerity



71/266


Summary of Scale Factors

9

0.5

A 2 2

3 3

3

C 1 0.5

0.5

1 0.5

2 3

23 7/2

12

12

1 0.5

D

1.

2. C/

3. () ?

Reference Full-Scale Spar Platform

C3 =50 =60 =75

B ( ) A ( ) 10

= / 0.200 0.167 0.133

( B ) A ( ) 87. 6 = / 1.752 1.460 1.168

() 249718

= /

31.998 1.156 0.592

() 77.6

= / 1.552 1.293 1.035

D () 3.78

= / 0.076 0.063 0.050

B D () 6.5

= / 0.130 0.108 0.087



72/266


FAST with AeroDyn and HydroDyn

11

Structural-dynamic model for horizontal-axis turbines:

Coupled to AeroDyn, HydroDyn, and controller for aero-hydro-servo-elastic simulation

Evaluated by Germanischer Lloyd WindEnergie

Turbine Configurations

HAWT

2 or 3-bladed

Upwind or downwind

Land-based or offshore

Offshore monopiles or floating

Rigid or flexible foundation

FAST Verification

Participated in OC3, which compared the results of avariety of load cases for the OC3 HyWind Spar, with the

NREL 5 MW turbine placed on top.

New verification efforts are looking at understandinglimitations in the HydroDyn Module of FAST



73/266


STEP 2:Testing of 1/3 Scale Model at Test Site

13

Approximately 1/3rd Scale of5MW

Commercial turbine with provenrecord of performance is planned

~100 kW (will be provided). Floating platform designs willbe selected from competitiveindustry solicitation

Turbine will be deployed attimes when desired scaled wind/wave conditions are present.

100 1/3

1/3 Scale Prototype Monhegan Island

Approx. 2.5 miles south

from Monhegan Island

Up to 400 ft depth

9.0 m/s +averagewinds



74/266


Test Window for 1/3 Scale Turbine

15

52%

69%

56%A 47%

28%

7%

0%

A 1%

4%

46% 58%

D 73%

Current Status of 1/3 Scale

A Request for Interest (RFI) forindustry participation in testing planhas been released

Several submissions have beenreceived. Prequalification questionnaires

have been reviewed.

A Request for Proposals (RFP) iscurrently under development.



75/266

FUNDACINCENTROTECNOLGICO DECOMPONENTES

SAEMar ProjectRal Rodrguez Arias

Head of Renewable Energies Unit

CTC

IEA R&D WIND TASK XI

Topical Expert Meeting #63on

HIGH RELIABILITY SOLUTIONS ANDINNOVATIVE CONCEPTS FOR OFFSHORE

WIND TURBINESSINTEF Energy Research, Trondheim, Norway

September 21-22 2010

SUMMARY



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1

CTC Presentation

Technological Centre of Components, CTC

CTC is a non-profit foundation and aims to contribute

to economic and social development, helping companies toassess the technological feasibility of their ideas, as well as

technically execute their R+D+I projects, as part of the

Science-Technology-Enterprise system.



77/266

SAEMarProject

FACILITIES

CTC is located in the Scientific and Technological Park ofCantabria (PCTCAN), in an enabling environment for activitiesrelated to R & D.

5

The new facilities include a laboratory with equipment and

space necessary for project implementation and research.

2



78/266

SAE

MarProject

SAEMar Project: an overview

7

SAEMar Project: Anchoring Systems for Renewable Marine EnergiesOffshore Platforms

National call: Fundamental and BasicResearch

Project Coordinator: CTC

Partners: Cantabria University and A CoruaUniversity

36 months (January 2011-December 2013)

Total budget: 811 K(420 k funded byMICINN)

3



79/266

SAE

MarProject

Project's main objective and key points

9

Main objetive

The main objective of the project is to create a methodology for thereliable design of the system formed by the mooring line-anchor-soil ofFloating Ocean Energy Platforms (FOEP).

Key points

Probabilistic design (level III) of the system life cycle (mooring line-anchor-terrain)

Mechanical design and material selection.

Fatigue analysis using advanced probabilistic methods of fracturemechanics.

Dynamic terrain of the seabed and hydrodynamic analysis platforms.

Laboratory experimental program, including not only hydrodynamic

tests in a wave tank, but also geotechnical testing of the seabedterrain.

SAEMar Project: initial hypothesis

The main reason to present this proposal is to cover the gaps ofscientific knowledge and to develop a specific methodology forthe selection and improved design of anchoring systems for aFOEP.

The initial hypothesis which support the objectives are the



80/266

SAE

MarProject

Specific objectives (I)

11

1. To develop specific methodologies for the analysis andselection of the suitable alternative of the anchoringsystem for an individual offshore floating moored platform.

2. Based on the previous objective, to adapt or develop

specific methodologies for the analysis and selection of the

suitable alternative of the anchoring system of a set of

platforms in a farm configuration.

3. To generate synergies in the knowledge of the

interrelationship mechanisms between the dynamics ofthe floating platforms, moorings systems, anchoring

systems and loads in the sea bottom materials.

PAGE11

Specific objectives (II)

4. Analyse different typologies of FOEPs, its anchoringsystems and the different sea bottom characteristics inorder to select some types for mooring lines forcesparameterization.

5. Analysis, parameterization and statistical descriptionh d l f f i h i



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4

Consortium and subprojects

Consortium and subprojects (I)



82/266

SAE

MarProject

Consortium and subprojects (II)

15

Consortium and subprojects (III)

SP1 (CTC): Methodologies to select and design the anchoringsystem in FOEP



83/266

SAE

MarProject

Consortium and subprojects (IV)

17

SP2 (UC): Hydrodynamics and Geotechnics of FOEP mooringSystems

Analysis, parameterization and statistical description (short and longterm) of the acting forces and loads in the mooring lines and anchorsdue to the combined actions induced by wind, waves and currents

Characterization of the response of the soil and its interaction withthe anchor

Consortium and subprojects (V)

SP3 (UDC): Life cycle and integration of FOEP mooring andanchoring system



84/266

5

Work Packages and dissemination activities

Workpackages (I)

Preliminary analysis: platform and mooringconfiguration (UDC)

WP 1.2

Coordination and dissemination (CTC)WP 1.1

SP1: Methodolog ies to select and design the anchoring

system in FOEP



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SAE

MarProject

Workpackages (II)

21

Geotechnical tests (UC-GG)WP 2.3

Offshore geothecnical analysis (UC-GG)WP 2.2

Platform Hydrodynamics (UC-IH)WP 2.1

Mooring platform interface: analysis and design (UDC)WP 3.3

Life cycle analysis of the mooring and anchoring systems(UDC)

WP 3.2

Mooring design (UDC)WP 3.1

SP3: Life cycle and integration of FOEP mooring and

anchoring system

SP2:Hydrodynamics and Geotechnics of FOEP mooring

Systems

Work Packages and dissemination activities

Dissemination activities

Exploitation and dissemination of project results will be achieved

at 3 levels:

1. Within the project team, project advances and results will be



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Thank you for yourattention

Questions?



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Taut mooring of floating wind turbines;

application examples and comparisons

(work in progress)

IEA Task XI Topical Expert Meeting 63, Trondheim,Norway, September 21-22, 2010

Tor Anders Nygaard

Institute for Energy Technology (IFE), Norway

[email protected]

Outline

Engineering challenges, floating wind turbines

Examples of conceptual designs



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Engineering Challenges

From the ocean engineers perspective: High thrust force andmass on top of structure giving overturning moment. The floatermust provide restoring moment to counteract this.

From the rotor aeromechanics engineers perspective: Largemotions compared to land-based or bottom-fixed towers. Windturbine suppliers are cautious about foundations with largemotions.

Strong coupling between aerodynamics, structural dynamics,hydrodynamics and control system

Strong cost constraints compared to the oil and gas industry

Examples

HYWIND



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HYWINDSpar-buoy with catenary lines. Floater

restoring moment and rotor motion control

by large floater, heavy ballast and

innovative pitch controller. Inertia-

controlled motions.

5 MW version OC3-HYWIND definedfor model development and benchmarking

in the IEA-OC3 project.

Jonkman, J. et al (2010). Offshore Code

Comparison Collaboration within IEA

Wind Task 23. Europen Wind Energy

Conference & Exhibition, Warsaw, Poland,

April 2010.

SWAY

Pre-stressed tower/floater spar withdownwind turbine. Restoring moment

by the horizontal offset betweencenter-of buoyancy and effective

S i S b ibl Wi dFl t



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Semi-Submersible - WindFloat

Restoring moment provided by heave

stiffness of three horizontally offset

cylinders.

Closed-loop water ballast system helps

maintaining vertical orientation of

tower.

Inertia- and damping control of motions.

Commercial development by Principal

Power Ltd.

Taut Line Buoy (TLB)Restoring moment and rotor

motion constraints by excessbuoyancy and prestressed taut

mooring in several heights.

All DOFs are stiffness-Wi d



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Previous work Worked with Christian Grorud from 2006, evaluating various

floaters with taut mooring in several heights:Nygaard, T. A., Myhr, A. and Maus, K. J. (2009). A comparisonof two conceptual designs for floating wind turbines. EuropeanOffshore Wind Conference & Exhibition, September 2009,

Stockholm, Sweden. The term TLB in the context of wind turbines appeared for the

first time in a paper by prof. Sclavonous, MIT at EWEC 2010:Sclavounos, P. D. et al.(2010). Floating wind turbines:Development of a Taught-Line-Buoy (TLB) concept. EuropeanWind Energy Conference (EWEC 2010), Warsaw, Poland, April2010

Motivation and aim

The aim is to develop cost-effective, stable platformsfor floating wind turbines, with properties comparableto bottom-fixed or onshore towers.

The savings in the floater could easily be lost due to

i d t f i li h d f t



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Approach

Design a TLB floater for the IEA 5MW referenceoffshore wind turbine.

Select mooring lines axial stiffness from Eigenfrequency analysis.

Determine pre-tension in the mooring lines, requiringthat a minimum level of pre-tension is maintainedduring a worst-case extreme event.

Run various load cases to estimate loads on the

mooring lines and anchors.

Example of TLB:

5MW application for 80m water depth

Above +10m: Identical to IEA OC3 5MW reference offshorewind turbine

Below +10m: Stripped down, ignoring redundancy and safetysystems, to provide estimate for maximum steel mass savings.D ft 50



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Eigen Frequency Analysis: Pitch : T = 4.9s

Surge: T = 2.3s



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Heave : T = 2.13s

First Bending : T = 0.94



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Second Bending : T = 0.46s

Extreme case:

Hs = 17m, Vhub = 65 m/s (steady)

Wave kinematics: Superposition of airy waves forfinite water depth, JONSWAP spectrum with peakperiod of 15.5 m/s. Phase, amplitude andwavenumber information is stored to provide identical

fi ld f h diff i l i



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Load case 5.1, IEA OC3



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,Regular airy waves, H = 6m T = 10s

Vhub = 11.4 m/s (steady)

Wave induced motion of nacelle causes power

variations, which in turn trigger pitch control actions,which in turn changes rotor trust, causing newmotions, and so on

Land based pitch controller was modified in IEA OC3project to provide stable behavior under operation

Both land-based and offshore controllers can be usedfor TLB



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TLB at other water depths

Continue upper ML down at same angle, 45 deg.Adjust EA to give same overall stiffness EA/L (fiberropes)

In this study, upper and lower ML are identical. Thisshould be studied closer, to optimize translatoryresponse to waves.

Example 2: TLB at 200m depth.

Upper and lower ML: Increase diameter with factor(200/80)**0.5 = 1.58. Otherwise identical

Ran same extreme case as earlier and comparedtower stresses to TLB at 80m depth

Comparison of TLBs at 80 and 200m depth



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Comparison of TLB s at 80 and 200m depth

Proposed variations

For a downwind turbine, upwind upper mooringline(s) can take position almost up to hub height. Thiswould increase pitch stiffness, and reduce the needfor axial

High Reliability Solutions & Innovative Concepts for Offshore Wind Turbines

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