Research Over From Risoe - P.H. Madsen

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17/04/2008Presentation name1 Risø DTU, Technical University of Denmark

Technology developments and R&D landscape:

Research overview from Risø

Peter Hauge Madsen

Wind Energy Division, Risø DTU

The Technical University of Denmark

Presented at

EU offshore wind industry - a Carbon Trust/EWEA event




Wind Energy Division - Risø DTUTechnical University of Denmark

• Windpower Meteorology

• Aeroelastic designmethods

• Wind Turbine Structures

• Offshore Wind Energy

•

Remote sensing & Measurements

• Windpower control & integration

• Certification Scheme

WIND ENERGYDIVISION

EDUCATION

WindTurbines

Wind EnergySystems

AeroelasticDesign

Test &Measurement

Meteorology

INTERNATIONALCONSULTING




”Wind Energy Roadmap” in the EC Communicationof Financing Low Carbon Technologies.

TPWind priorities 2010-2012:

•Development andtesting of newstructures

•Automation (industry-wide study)

•Technology transfer

from oil & Gas




Research, development and demonstrationchallenges – Danish MEGAVIND strategy

Target to make offshore wind power competitive with conventional coal-

fired power by 2020 (50 % reduction in cost).




EERA JP on Wind Energy




EERA JPWEEERA JP on Wind Energy




Wind Energy Division - Risø DTUTechnical University of Denmark

WIND ENERGYDIVISION

EDUCATION

WindTurbines

Wind EnergySystems

AeroelasticDesign

Test &Measurement

Meteorology

INTERNATIONAL

CONSULTING

Offshore Wind Energy

DTU MEK

DTU IMM

DTU BYG




Risø DTU – Offshore Wind Energy R&Dpriorities

• Marine wind, wave and current conditions– Characterize the geophysical processes,estimate local

conditions and develop design basis

• Wakes in offshore wind turbine farms– Characterize and model wakes (performance and loads) in

relation to interaction between turbines, between farms and

large scale climate effects

• Installation and maintenance– Methods, models and tools to support installation and

maintenance incl. Wind wave prediction, remedial andpreventive maintenance and condition monitoring

• Integrated design tools

– Integrated aero-hydro-servo-elastic tools incl. waveloads,soil-structure and fluid-structure interaction

• Offshore wind integration– Models and tools for design and control of offshore grid and

clusters

• New concepts

0

100

200

300

400

500

600

700

800

Time

P o w e r ( M W )

HRB

HRA

HR2

HR1

8 /1 -2 000 9 /1 -2 00 0 3 0/ 1- 20 00 3 1/ 1- 20 00 1 /2- 20 00




Offshore Wind Conditions

• Ocean winds • Lidar observations and

modelling

• Wind resourcemapping using satellitedata

• Mesoscale modelling • Meteorological mast

observations

• Wind farms shadoweffect

• Satellite observations

Lidar wind data and

model from Horn’s

Reef offshore

Satellite winds

showing the

wake at Horn

Reef wind farm.

Mean wind

speed map using

satellite Envisat

ASAR.




Horns Rev offshore site

Courtesy: DONG Energy

and Alfredo Peña, Risø DTU




Wind loads dominated by wake effects

CFD – Large eddysimulation




Fuga – a new, linearized wake model

• Solves linearised RANS equations

• Closure: mixing length, k -e or ’simple’ (nt=ku* z )

• Fast, mixed-spectral solver using pre-calculated look-up tables (LUTs)

• No computational grid, no numerical diffusion, no spurious meanpressure gradients

• Integration with WAsP: import of wind climate and turbine data.

• 105 times faster than conventional CFD!




User friendly GUI




Validation: Horns Rev I.

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1 2 3 4 5 6 7 8 9 10

N o r m a l i z

e d p r o d .

Row number

270+-7.5 Fuga

270+-12.5 Fuga

270+-17.5 Fuga

270+-7.5 Data

270+-12.5 Data

270+-17.5 Data

Simple closure: nt=ku* z

No adjustable parameters!




Validation: Nysted.

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1 2 3 4 5 6 7 8

N o r m a l i z e d p r o

d u c t i o n

Row number

273+-7.5Fuga273+-12.5Fuga273+-17.5Fuga273+-7.5Data273+-12.5Data

273+-17.5Data

Simple closure: nt=ku* z




Downwind Speed Recovery

• FUGA - predicts a much ”slower” speed recovery than standard wakemodels.

• For HR rec.distance is about 16 km; somewhat slower than observed 4)

Normalized wind speed through the windfarm and behind the wind farm compared tomeasurements at Horns rev. Full curves arecanopy-CFD-model predictions.

_______________________________________________________________________________________

4) R.J.Barthelmie et al., ” Flow and wakes in large wind farms: Final report for UpWind WP8”. Risø-R1765(EN) (2011).




Design of offshore wind turbines

– Offshore wind turbines are not onshore wind turbines!• hydrodynamic loads, sea ice, long periods at standby

– Offshore wind turbines are not oil rigs!• wind loads, shallow water, dynamics, unmanned

– Marriage of expertise from wind power and offshoreengineering industries

– Technology Risks• Improve confidence with which offshore wind farms can be financed

and implemented

s u b - s t r u c t u r e

p i l e

f o u n d a t i o n

p i l e

p l a t f o r m

t o w e r t o w e r

s u b - s t r u c t u r e

sea floor

s u p p o r t s t r u c t u r e

rotor-nacelle assembly

seabed

water level




Standards for Offshore Wind Turbines

•Onshore wind turbines– IEC 61400-1, Edition 3

•Offshore wind turbines– IEC 61400-3

– GL Regulations for Offshore WECS, 1995

– DNV, Design of Offshore Wind Turbine Structures, OS-J101, 2007

– GL Wind, Guideline for the Certification of Offshore WindTurbines, 2005

•Offshore structures – petroleum and naturalgas industries

– ISO 19900, General Requirements for Offshore Structures, 2002– ISO 19901, Specific Requirements for Offshore Structures, 2003

– ISO 19902, Fixed Steel Offshore Structures, 2004 (DIS)

– ISO 19903, Fixed Concrete Offshore Structures, 2004 (DIS)




Walney Offshore Wind Farm Project

1. Large offshore wind farm beingconstructed by DONG energy with~50 machines in phase 1

2. Siemens 3.6MW machines withmonopile foundations

3. Average HH wind speed: 9.3 m/sec

4. Water depth 19m –28 m

Objectives

1. Database of loads measurements with correlated wind and wave

data

2. Assessment of uncertainty in loads simulations to provide improvedstructural reliability.

3. Recommendations to international wind turbine standards onoffshore turbine design.

Partners: Risø DTU, DONG, Siemens




EUDP Walney Offshore Wind Farm Project

Measurements:

• Nacelle mounted LIDARmeasuring wind speed at 2.5rotor diameter in front of turbine.

• Wave and current

measurements near foundation




Benefits from the project and its need

1. Maturity of loads prediction on offshore wind turbines,both on the support structure, as well as rotor nacelle.

• Provides offshore turbine loads data for research purposes.

• Provides for correlated wind and wave measurements for eachload data point.

• One of the very few nacelle mounted LIDARs for offshore windturbines with accurate wind measurements

2. Cost effective foundations.– Improved accuracy for site specific loads prediction

– Estimation of damping of the structure to mitigate fatigue andextreme loads

3. Long term loads on the foundations– Fatigue and ultimate strength requirement evaluations

– Enables improved life prediction




DEEPWIND – New EU Funded Program

Vertical axis wind turbine

Bottom mounted generator for weight savings




Mooring point

Wave energyconversion device

3x GAIA 11kW. Downwind,Free yaw and teetering

Grid connectionpoint

PSO project, measurements and modeling: DONG, FPP, DHI and Risø DTU

Combined floating wind- and wave energyconverter – Poseidon Experiment




Poseidon: Modeling Challenges

Risø Hawc2 Overview

• Three rotors in one simulation

– Structural modeling already possible in the multi-body formulation

– Aerodynamic model updated to handle this

• Wake from upwind rotors

– Already possible with the dynamic wake meandering model in HAWC2

• Large water surface area

• Full coupled HAWC2-WAMSIM simulations• HAWC2 validated aeroelastic code

• WAMSIM validated radiation/diffractioncode for dynamic of floating structuresfrom DHI

• WAMSIM recode to HAWC2 dll-interface

format• Ordinary HAWC2 turbine model

• Ordinary WAMSIM model

• Full system solved by HAWC2




• The development of offshore wind energy depends notonly on industrial development and demonstration –butalso on medium to long term research

• Site conditions very complex – the site specific designconditions are derived in an ad-hoc and pragmatic way

• Integrated design tools exist but are primarily used todemonstrate conservatism of approach

• Limited validation of design loads and response

• Deep water (> 30 m) is a challenge

• Deep water concepts under way

• Offshore wind is just at the beginning – all options areopen

Conclusions




Thank you for yourattention

Research Over From Risoe - P.H. Madsen

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