Fatigue loads on offshore wind turbines due to weakly non-linear waves
Paper i proceeding, 2005

Due to the pronounced dynamic behavior of wind turbines, fatigue load effects may be quite sensitive to the precise modeling of the frequency content of the wave loading. As the offshore wind turbine technology progresses, larger and larger turbines will be placed at still deeper waters, causing the resonant frequency of the first eigen mode of a traditional bottom-fixed support structure to be typically in the range from 0.25 Hz to 0.35 Hz. The deeper the water and the larger the turbine, the lower the frequency will be. As an example, wave measurements from the offshore wind farm Bockstigen show a second peak at approximately 0.3 Hz in the wave spectrum. Thus this peak, or similar peaks realized at shallow water sites, may very well be dynamically amplified in the response. This second peak cannot be modelled with a linear wave model, and a wave model taking non-linearities into account has to be used. In the presented work, both a linear and a non-linear wave model are used to study the fatigue in an offshore wind power plant and the difference is compared. Time series of irregular linear and non-linear waves are calculated, and structural calculations of an offshore wind turbine with a slender support structure are used in the analysis of the fatigue loads. The forces on the structure are calculated using Morison's equation, integrating along the structure and lumping the loads in nodes for the structural calculations. The difference between the wave models is significant and the non-linear model yields higher fatigue damage than the linear one. Copyright © 2005 by ASME.

Fatigue

Wind Energy Converter

Non-linear Waves

Wave Load

Författare

Jenny Trumars

Chalmers, Bygg- och miljöteknik, Vatten Miljö Teknik

Niels Jacob Tarp-Johansen

Danmarks Tekniske Universitet (DTU)

Thomas Krogh

Danmarks Tekniske Universitet (DTU)

Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE

Vol. 2 483-492 OMAE2005-67064

24th International Conference on Offshore Mechanics and Arctic Engineering, 2005
, Greece,

Ämneskategorier

Teknisk mekanik

Marin teknik

Annan elektroteknik och elektronik

DOI

10.1115/OMAE2005-67064

Mer information

Senast uppdaterat

2020-03-10