comparison of measured and simulated responses...

Classification: Internal 2011-03-09

Comparison of measured and simulated responsesat the first full scale floating wind turbine Hywind

Tor David Hanson

Bjørn Skaare

Rune Yttervik

Finn Gunnar Nielsen

Ole Havmøller

Classification: Internal 2011-03-09 Classification: Internal Status: Draft

Hywind located 10 km west of Karmøy, Norway

Karmøy

Main particulars

Siemens turbine: 2.3 MWTurbine weight: 138 tonsDraft hull: 100 mNacelle height: 65 mRotor diameter: 82.4 mWater depth: 200-220 mDisplacement: 5300 tMooring: 3 linesDiameter at water line: 6 mDiam. submerged body: 8.3 m


Hywind Demo full scale measurements

•A total of more than 200 sensors:

– Waves wind and current (magnitude and direction)

– Motion (6 DOF) and position of floater

– Mooring line tension

– Strain gauges at tower and hull (4 levels – bending moments and axial force)

– Rotor speed, blade pitch and generator power

– Flap- and edgeways rotor bending moments

Motion (tower pitch) / blade pitch controllers


Operations first winter season - Active power

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

x 107

0

0.5

1

1.5

2

2.5

3Active Energy Production

time [s]

Act

ive

Ene

rgy

Pro

duct

ion

[GW

h]

01.10.2009 23.01.20

1021.05.2010


Significant Wave Height first winter season

01.10.2009

23.01.2010

21.05.2010

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

x 107

0

1

2

3

4

5

6

7

8

9

10

Significant Wave Height

time [s]

Hs

[m]


Wave height and wind speed

0

0.5

1

1.5

2

2.5

3

3.5

Case

Wav

e he

ight

[m]

A B

C

0

5

10

15

20

25

Case

Win

d sp

eed

[m/s

]

AB

C


Simulation tools


Tower pitch & roll, and tower bending moments


Pitch and roll motion – Case A normal production

0 0.05 0.1 0.15 0.2 0.250

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Hz

sqrt(

S(f))

Measured NSSimulated NSMeasured EWSimulated EW


Pitch and roll motion – Case B normal production

0 0.05 0.1 0.15 0.2 0.250

1

2

3

4

5

Hz

sqrt(

S(f)

)



Pitch and roll motion – Case C Idling

0 0.05 0.1 0.15 0.2 0.250

0.5

1

1.5

2

2.5

Hz

sqrt(

S(f))



Tower bending – Case A – normal production

0 0.5 1 1.5 20

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Hz

sqrt(

S(f))



Tower bending – Case B – Normal operation

0 0.5 1 1.5 20

1000

2000

3000

4000

5000

6000

7000

8000

9000

Hz

sqrt(

S(f))



Tower bending case C - Idling

0 0.5 1 1.5 20

2000

4000

6000

8000

10000

12000

Hz

sqrt(

S(f))



Conclusions•Three well defined short term load cases with stable statistical parameters from the first winter

season of the data acquisition program for Hywind Demo (January to April 2010) have been studied.

•During this season no extreme wave conditions were measured. The highest recorded significant wave height was less than 6.0 metres. However occurrences of 10 minutes mean wind speed above 30 m/s have been recorded.

•The comparison of measured and simulated dynamic responses including natural frequencies shows in general quite good agreement. However, simulated high frequency elastic response is under-predicted due to the selected analysis approach utilizing two equation solvers.

•The wave loads in the simulations have been based on long crested sea. An additional source of uncertainty is related to the formulation of the wave spectrum in the simulations. This differs from the real wave spectrum.

•The wind sensor is located at the nacelle behind the rotor. Hence, it is difficult to estimate the exact free wind velocity and the turbulence level.

•The simulations presented above are made by a special purpose coupled analysis tool calibrated by, amongst others, model tests.


Comparison of measured and simulated responses at the first full scale floating wind turbine Hywind

Tor David Hanson

Thank you!

comparison of measured and simulated responses...

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