Extreme Loads And Fatigue Loads Of Offshore Wind Turbines

Under the global background of energy conservation, emission reduction anddeveloping of renewable energy, wind energy has a promising application prospect.Compared with onshore wind power, offshore wind power is an important direction ofthe wind power development. However, how to forecast the ultimate structure loadunder the function of the wind coupled with the corresponding sea wave is still achallenge. This paper, mainly according to the requirement of IEC61400-3, studies theblade loads and the tower loads of the offshore wind turbines.The main contents of this paper are as follows:1): Introduce the current development all over the world and the development prospectof the offshore wind turbines, with the significance of this study discussed.2): NREL5MW Monopile, OC3Hywind, TLP and Barge offshore wind turbines arestudied to predict long-term loads of offshore wind turbines, which contributes to thecomparison of the extreme loads and fatigue loads of different floating offshore windturbines.3): Compile FAST to include the functionality of calculating the wind loads on thetower in the simulation. Using the global maximum and block maximum, two statisticsextrapolation methods respectively to fit Gumbel distribution to predict the extremeload of out-of-plane bending moment at the blade root, with results compared. Further,discussing different block sizes, the optimal block size is suggested. Research resultscomparison with peak-over-threshold method shows that the block maximum methodcan effectively predict loads, thus providing references for offshore wind turbines loadcalculation.4): Study the impact of different foundation models of the Monopile fix-bottom windturbine on the long term loads of the blade and the tower. Under the condition ofensuring the accuracy and computational efficiency, develop a program based onsimulations to get the characteristic loads required.