5 research outputs found
OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine
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 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.This work was supported by the U.S. Department of Energy under Contract No. DEAC36-
08GO28308 with the National Renewable Energy Laboratory. Some of the
funding for the work was provided by the DOE Office of Energy Efficiency and
Renewable Energy, Wind and Water Power Technologies Office
Verification of a Numerical Model of the Offshore Wind Turbine From the Alpha Ventus Wind Farm Within OC5 Phase III
The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project, is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project analyzes the Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. This paper shows results of the verification of the OWT models (code-to-code comparison). A subsequent publication will focus on their validation (comparison of simulated results to measured physical system response data). Based on the available data, the participants of Phase III set up numerical models of the OWT in their simulation tools. It was necessary to verify and to tune these models. The verification and tuning were performed against an OWT model available at the University of Stuttgart - Stuttgart Wind Energy (SWE) and documentation provided by Senvion and OWEC Tower. A very good match was achieved between the results from the reference SWE model and models set up by OC5 Phase III participants
OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design
This paper provides a summary of the work done within the OC6 Phase II project, which was focused on the implementation and verification of an advanced soil–structure interaction model for offshore wind system design and analysis. The soil–structure interaction model comes from the REDWIN project and uses an elastoplastic, macroelement model with kinematic hardening, which captures the stiffness and damping characteristics of offshore wind foundations more accurately than more traditional and simplified soil–structure interaction modeling approaches. Participants in the OC6 project integrated this macroelement capability to coupled aero-hydro-servo-elastic offshore wind turbine modeling tools and verified the implementation by comparing simulation results across the modeling tools for an example monopile design. The simulation results were also compared to more traditional soil–structure interaction modeling approaches like apparent fixity, coupled springs, and distributed springs models. The macroelement approach resulted in smaller overall loading in the system due to both shifts in the system frequencies and increased energy dissipation. No validation work was performed, but the macroelement approach has shown increased accuracy within the REDWIN project, resulting in decreased uncertainty in the design. For the monopile design investigated here, that implies a less conservative and thus more cost-effective offshore wind design
Verification of Numerical Offshore Wind Turbine Models Based on Full Scale Alpha Ventus Data within OC5 Phase III
The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project, is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project analyzes the Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. This paper shows results of the verification of the OWT models (code-to-code comparison). A subsequent publication will focus on their validation (comparison of simulated results to measured physical system response data). Based on the available data, the participants of Phase III set up numerical models of the OWT in their simulation tools. It was necessary to verify and to tune these models. The verification and tuning were performed against an OWT model available at the University of Stuttgart – Stuttgart Wind Energy (SWE) and documentation provided by Senvion and OWEC Tower. A very good match was achieved between the results from the reference SWE model and models set up by OC5 Phase III participants