Abstract
The current design of offshore wind turbines follows mainly the IEC 61400-3 standard. The list of Design Load Cases (DLCs) implied for this standard is comprehensive and the resulting number of time domain simulations is computationally prohibitive. The aim of this paper is to systematically analyse a subset of ultimate limit state load cases proposed by the IEC 61400-3, and understand the relative severity among the load cases to identify the most critical among them. For this study, attention is focused on power production and parked load cases. The analysis is based on the NREL 5 MW prototype turbine model, mounted on a monopile with a rigid foundation. The mudline overturning moment, as well as the blade-root in-plane and out-of-plane moments are taken as metrics to compare among the load cases. The simulations are carried out using the aero-hydro-servo-elastic simulator, FAST, and the key observations are thoroughly discussed. The DLC 1.6a is shown to be the most onerous load case. Although the considered load cases are limited to power production and idling regimes, the obtained results will be extremely useful for the substructure (monopile) design and for efficient reliability analysis subsequently, as is also shown partially by some previous studies.
Original language | English |
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Pages (from-to) | 126-143 |
Number of pages | 18 |
Journal | Renewable Energy |
Volume | 101 |
Early online date | 1 Sept 2016 |
DOIs | |
Publication status | Published - 1 Feb 2017 |
Bibliographical note
This PhD research is funded by Lloyd’s Register Group Services Ltd., Aberdeen. Sriramula’s work within the Lloyd’s Register Foundation Centre for Safety and Reliability Engineering at the University of Aberdeen is supported by Lloyd’s Register Foundation. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research. We would also like to acknowledge the constant assistance provided by Jason Jonkman on using FAST.Keywords
- Offshore wind turbine
- design load case
- monopile
- response analysis
- support structure
- ultimate load