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Title: OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine

Abstract

This 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 wave-excitation forces outside the linearmore » 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.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [4];  [5];  [6];  [6];  [7];  [7];  [8];  [9];  [9];  [10];  [11];  [12];  [13];  [14];  [15] more »;  [16];  [16];  [17];  [18];  [19];  [20];  [21] « less
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Fraunhofer Inst. for Wind Energy and Energy System Technology, Bremerhaven (Germany)
  3. Univ. of Maine, Orono, ME (United States)
  4. Maritime Research Inst., Wageningen (Netherlands)
  5. 4Subsea, Nesbru (Norway)
  6. National Renewable Energy Centre (CENER), Navarra (Spain)
  7. Centre for Marine Technology and Ocean Engineering (CENTEC), Lisbon (Portugal)
  8. DNV GL, Bristol (United Kingdom)
  9. Technical Univ. of Denmark, Lyngby (Denmark)
  10. European Centre of the Netherlands, Petten (Netherlands)
  11. Inst. for Energy Technology (IFE), Kjeller (Norway)
  12. IFP Energies nouvelles, Rueil-Malmaison (France)
  13. PRINCIPIA, Nantes (France)
  14. Politecnico di Milano (Italy)
  15. Siemens PLM, Barcelona (Spain)
  16. Tecnalia, San Sebastian (Spain)
  17. Univ. de Cantabria, Cantabria (Spain). IH Cantabria
  18. Univ. of Ulsan, Ulsan (South Korea)
  19. Univ. of Tokyo (Japan)
  20. Univ. Politecnica de Catalunya (Spain)
  21. WavEC Offshore Renewables, Lisbon (Portugal)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
OSTI Identifier:
1416253
Report Number(s):
NREL/JA-5000-68050
Journal ID: ISSN 1876-6102
Grant/Contract Number:
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Energy Procedia
Additional Journal Information:
Journal Volume: 137; Journal Issue: C; Journal ID: ISSN 1876-6102
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; 42 ENGINEERING; floating offshore wind turbine; DeepCwind semisubmersible; numerical modeling; verifcation; validation; IEA Wind

Citation Formats

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, and Debruyne, Yannick. OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine. United States: N. p., 2017. Web. doi:10.1016/j.egypro.2017.10.333.
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. OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine. United States. doi:10.1016/j.egypro.2017.10.333.
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, and Debruyne, Yannick. Sun . "OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine". United States. doi:10.1016/j.egypro.2017.10.333. https://www.osti.gov/servlets/purl/1416253.
@article{osti_1416253,
title = {OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine},
author = {Robertson, Amy N. and Wendt, Fabian and Jonkman, Jason M. and Popko, Wojciech and Dagher, Habib and Gueydon, Sebastien and Qvist, Jacob and Vittori, Felipe and Azcona, José and Uzunoglu, Emre and Soares, Carlos Guedes and Harries, Rob and Yde, Anders and Galinos, Christos and Hermans, Koen and de Vaal, Jacobus Bernardus and Bozonnet, Pauline and Bouy, Ludovic and Bayati, Ilmas and Bergua, Roger and Galvan, Josean and Mendikoa, Iñigo and Sanchez, Carlos Barrera and Shin, Hyunkyoung and Oh, Sho and Molins, Climent and Debruyne, Yannick},
abstractNote = {This 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 wave-excitation 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.},
doi = {10.1016/j.egypro.2017.10.333},
journal = {Energy Procedia},
number = C,
volume = 137,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}

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  • This paper examines how to assess the uncertainty levels for test measurements of the Offshore Code Comparison, Continued, with Correlation (OC5)-DeepCwind floating offshore wind system, examined within the OC5 project. The goal of the OC5 project was to validate the accuracy of ultimate and fatigue load estimates from a numerical model of the floating semisubmersible using data measured during scaled tank testing of the system under wind and wave loading. The examination of uncertainty was done after the test, and it was found that the limited amount of data available did not allow for an acceptable uncertainty assessment. Therefore, thismore » paper instead qualitatively examines the sources of uncertainty associated with this test to start a discussion of how to assess uncertainty for these types of experiments and to summarize what should be done during future testing to acquire the information needed for a proper uncertainty assessment. Foremost, future validation campaigns should initiate numerical modeling before testing to guide the test campaign, which should include a rigorous assessment of uncertainty, and perform validation during testing to ensure that the tests address all of the validation needs.« less
  • This paper examines how to assess the uncertainty levels for test measurements of the Offshore Code Comparison, Continued, with Correlation (OC5)-DeepCwind floating offshore wind system, examined within the OC5 project. The goal of the OC5 project was to validate the accuracy of ultimate and fatigue load estimates from a numerical model of the floating semisubmersible using data measured during scaled tank testing of the system under wind and wave loading. The examination of uncertainty was done after the test, and it was found that the limited amount of data available did not allow for an acceptable uncertainty assessment. Therefore, thismore » paper instead qualitatively examines the sources of uncertainty associated with this test to start a discussion of how to assess uncertainty for these types of experiments and to summarize what should be done during future testing to acquire the information needed for a proper uncertainty assessment. Foremost, future validation campaigns should initiate numerical modeling before testing to guide the test campaign, which should include a rigorous assessment of uncertainty, and perform validation during testing to ensure that the tests address all of the validation needs.« less
  • During the course of the Offshore Code Comparison Collaboration, Continued, with Correlation (OC5) project, which focused on the validation of numerical methods through comparison against tank test data, the authors created a numerical FAST model of the 1:50-scale DeepCwind semisubmersible system that was tested at the Maritime Research Institute Netherlands ocean basin in 2013. This paper discusses several model calibration studies that were conducted to identify model adjustments that improve the agreement between the numerical simulations and the experimental test data. These calibration studies cover wind-field-specific parameters (coherence, turbulence), hydrodynamic and aerodynamic modeling approaches, as well as rotor model (blade-pitchmore » and blade-mass imbalances) and tower model (structural tower damping coefficient) adjustments. These calibration studies were conducted based on relatively simple calibration load cases (wave only/wind only). The agreement between the final FAST model and experimental measurements is then assessed based on more-complex combined wind and wave validation cases.« less