Browsing by Keyword "Floating offshore wind turbine"
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Item OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine(2017-10) Robertson, Amy N.; Wendt, Fabian; Jonkman, Jason M.; Popko, Wojciech; Dagher, Habib; Gueydon, Sebastien; Qvist, Jacob; Vittori, Felipe; Azcona, José; Uzunoglu, Emre; Soares, Carlos Guedes; Harries, Rob; Yde, Anders; Galinos, Christos; Hermans, Koen; de Vaal, Jacobus Bernardus; Bozonnet, Pauline; Bouy, Ludovic; Bayati, Ilmas; Bergua, Roger; Galvan, Josean; Mendikoa, Iñigo; Sanchez, Carlos Barrera; Shin, Hyunkyoung; Oh, Sho; Molins, Climent; Debruyne, Yannick; RENOVABLES OFFSHOREThis paper summarizes the findings from Phase II of the Offshore Code Comparison, Collaboration, Continued, with Correlation project. The project is run under the International Energy Agency Wind Research Task 30, and is focused on validating the tools used for modeling offshore wind systems through the comparison of simulated responses of select system designs to physical test data. Validation activities such as these lead to improvement of offshore wind modeling tools, which will enable the development of more innovative and cost-effective offshore wind designs. For Phase II of the project, numerical models of the DeepCwind floating semisubmersible wind system were validated using measurement data from a 1/50th-scale validation campaign performed at the Maritime Research Institute Netherlands offshore wave basin. Validation of the models was performed by comparing the calculated ultimate and fatigue loads for eight different wave-only and combined wind/wave test cases against the measured data, after calibration was performed using free-decay, wind-only, and wave-only tests. The results show a decent estimation of both the ultimate and fatigue loads for the simulated results, but with a fairly consistent underestimation in the tower and upwind mooring line loads that can be attributed to an underestimation of waveexcitation forces outside the linear wave-excitation region, and the presence of broadband frequency excitation in the experimental measurements from wind. Participant results showed varied agreement with the experimental measurements based on the modeling approach used. Modeling attributes that enabled better agreement included: the use of a dynamic mooring model; wave stretching, or some other hydrodynamic modeling approach that excites frequencies outside the linear wave region; nonlinear wave kinematics models; and unsteady aerodynamics models. Also, it was observed that a Morison-only hydrodynamic modeling approach could create excessive pitch excitation and resulting tower loads in some frequency bands.Item A Simplified Modeling Approach of Floating Offshore Wind Turbines for Dynamic Simulations(2022-03-18) López-Queija, Javier; Robles, Eider; Llorente, Jose Ignacio; Touzon, Imanol; López-Mendia, Joseba; Tecnalia Research & Innovation; RENOVABLES OFFSHORECurrently, floating offshore wind is experiencing rapid development towards a commercial scale. However, the research to design new control strategies requires numerical models of low computational cost accounting for the most relevant dynamics. In this paper, a reduced linear time-domain model is presented and validated. The model represents the main floating offshore wind turbine dynamics with four planar degrees of freedom: surge, heave, pitch, first tower foreaft deflection, and rotor speed to account for rotor dynamics. The model relies on multibody and modal theories to develop the equation of motion. Aerodynamic loads are calculated using the wind turbine power performance curves obtained in a preprocessing step. Hydrodynamic loads are precomputed using a panel code solver and the mooring forces are obtained using a look-up table for different system displacements. Without any adjustment, the model accurately predicts the system motions for coupled stochastic wind–wave conditions when it is compared against OpenFAST, with errors below 10% for all the considered load cases. The largest errors occur due to the transient effects during the simulation runtime. The model aims to be used in the early design stages as a dynamic simulation tool in time and frequency domains to validate preliminary designs. Moreover, it could also be used as a control design model due to its simplicity and low modeling order.