Session: 09-01-03 Installation, Marine Operations and Maintenance - 3

Paper Number: 80112

80112 - Life Cycle Response Analysis of a Floating Offshore Wind Turbine 

The offshore wind industry trend is towards larger floating wind turbines to lower the Levelized Cost of Energy (LCOE). It is anticipated that by 2025, 13-15MW turbines will be employed. In addition, offshore wind farms will target deeper waters, using floating substructures to support these large wind turbines, where greater wind resources are available. On the other hand, the larger turbines pose several challenges. For instance, a generic IEA 15MW turbine [1] has a large rotor diameter and hub height in the order of 240m and 150m respectively and is more difficult to design, install and maintain.

The challenges related to a large floating wind turbine design and analysis are to model the fully coupled system that includes flexible turbine tower dynamics, rotor dynamics, and the floating platform dynamics. In addition, unlike Oil and Gas floating platform analysis, a floating offshore wind turbine design and analysis requires more design load cases to be reviewed due to the various wind turbine operating conditions. Therefore, selecting the proper load case combinations for the wind turbine and floating platform coupled system is also very challenging.

In order to overcome these challenges, two existing numerical codes, OpenFAST [2], developed by the National Renewable Energy Laboratory (NREL), and MLTSIM, a Technip Energies proprietary software, were integrated into one code, MLTSIM-OpenFAST. In this integrated program, the turbine tower and rotor dynamics are simulated by the subroutines of OpenFAST, and the hydrodynamic loads and mooring system dynamics are simulated by the subroutines of MLTSIM. In the present study, MLTSIM-OpenFAST, which has been validated through OC3 DeepCwind model tests [3][4], has been utilized for simulating the entire service life of a floating offshore wind turbine using a direct time domain simulation method in High Performance Computing (HPC). In this simulation method, every 3-hours for 25 years of the floating offshore wind turbine responses were analyzed instead of using a conventional design load case analysis method. 

The novelty of this research is simulating the entire service life of a floating wind turbine in time domain, including   operability, power output and fully coupled responses of the wind turbine and floating platform. Furthermore, this research will discuss utilizing the simulated data for training AI and smart monitoring applications.

References

[1] Gaertner, E., Rinker, J., Sethuraman, L., Zahle, F., Anderson, B., Barter, G., Abbas, N., Meng, F., Bortolotti, P., Skrzypinski, W., Scott, G., Feil, R., Bredmose, H., Dykes K., Shields, M., Allen, C., and Viselli, A., May 2019, Definition of the IEA 15-Megawatt Offshore Reference Wind Turbine, in IEA Wind TCP Task 35,

[2] NREL, 2021, June, OpenFAST Document, https://openfast.readthedocs.io/en/main/

[3] Koo, B., Goupee, A., Lambrakos, K., and Lim, H., 2013 “Model Test Correlation Study for a Floating Wind Turbine on a Tension Leg Platform”, OMAE2013-1590 

[4] Koo, B., Goupee, A., Lambrakos, K., and Lim, H., 2014 “Model Test Data Correlations with Fully Coupled Hull/Mooring Analysis for a Floating Wind Turbine on a Semi-Submersible Platform”, OMAE2014-24254 

Presenting Author: Bonjun Koo Technip Enegies

Authors:

Bonjun Koo Technip Enegies
Chan Jeong Fugro USA
Hyoungchul Kim Technip Energies
Ho-Joon Lim Technip Energies
Lawrence Lai Technip Energies
Hyunchul Jang Technip Energies