Large Scale Assembly and Erection of Floating Offshore

Wind TurbinesM.Sc Anders Myhr

M.Sc David W. Moss

Prof. Tor Anders Nygaard

European Offshore Wind, Stockholm

16.09.2009

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Aquilo, the concept

Flexible and simple

Minimize risk Horizontal assembly

Reduce the number of vessels

and cranes during the operation

Optimized and developed for

turbines with single buoy floaters

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Development of model ANSYS finite element model of semisub-

platform, cradle and wind turbines

Platform setup: Metacentric height > 1 meter

Natural periods > 20 sec

Wave forces by Morrison’s Equation

Point pre-calculated wind force

Buoyancy

Gravity

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Time [s]

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Limits and assumptions

Operate during 90% of

North Sea weather conditions

Linear wave trains with a

significant wave height of 6m

Static wind field with a

speed of 36 m/s

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Wind speed [m/s]

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Turbine loads in horisontal position

Cantilever

Nacelle loads

Necessary length of Aquilo

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Length from tower base [m]

Length from tower base [m]

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Turbine loads in vertical position

Wind force

Wave force

Keel-effect

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Point forces [N]

Wind force [N/m]

Wave force [N/m]

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Loads during pivotation

Peak loads

Model errors

Wave slamming

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Horizontal position

Vertical position

During pivotation

Fatigue of the construction

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Evaluation

Assembly frequency

Investment cost

Flexibility

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Conclusion

The Aquilo concept should be a decent contender in future assembly and erection of offshore wind turbines.

The versatility for application on different assembly platforms are yet to be proven but should result in lesser dynamic response and loading on both the pivot cradle and turbine towers.

Further work:

More load combinations

Damping and Eigen-frequencies

Winches and anchor handling

Economics

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Thank you for your time.

For further information please contact me at: myhr.anders@gmail.com

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