Subtask 2 Past Meetings and Associated Documents and Research Results
The list on the left represent all the meetings of Task 23 Subtask 2.
All of the presentations and reports are part of the of public record.
The following FTP information takes you to the research results of Subtask 2
Codes Comparison Collaborative
(OC3)
Hostname: ftp.ieawind.org
Username: task23@ieawind.org
Password: OC3 (Case Sensitive)
Cost-effective offshore wind turbines make use of a variety of support structures including floating structures, fixed-bottom monopiles, gravity bases, and space-frames—such as tripods and lattice frames (“jackets”). In recent years, codes originally used for analysis of land-based wind turbine have been expanded to include additional dynamics pertinent to offshore installations, including the incident waves, sea current, hydrodynamics, and foundation dynamics of the support structure. This OC3 work was begun to validate these sophisticated codes and to verify their accuracy and correctness for offshore wind systems.
To test the newly developed codes, the OC3 participants met frequently to discuss modeling strategies, develop a suite of benchmark models and simulations, run the simulations and process the simulation results, and compare and discuss the results. The OC3 project was performed through technical exchange among a group of international participants from universities, research institutions, and industry researchers in Denmark, Germany, the Republic of Korea, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and the United States. Most of the aero-hydro-servo-elastic codes developed for modeling the dynamic response of offshore wind turbines and available in 2009 were tested within OC3.
Unlike previous code verification activities, this OC3 work was designed to verify the dynamics of offshore support structure as part of the dynamics of the complete system. To encompass the variety of support structures required for cost effectiveness at varying offshore sites, different support structures (for the same wind turbine) were investigated:
• In Phase I, the NREL-designed simulation of a 5-MW offshore wind turbine was installed on a monopile with a rigid foundation in 20 m of water.
• In Phase II, the foundation of the monopile from Phase I was made flexible by applying different models to represent the soil-pile interactions.
• In Phase III, the water depth was changed to 45 m and the monopile was replaced with a tripod substructure, which is one of the common space-frame concepts proposed for offshore installations in water of intermediate depth.
• In Phase IV, the wind turbine was installed on a floating spar-buoy in deep water (320 m).
The verification activities performed in OC3 were important because the advancement of the offshore wind industry is closely tied to the development and accuracy of dynamics models. Vital experiences and knowledge been exchanged among the project participants, and the lessons learned have helped identify deficiencies in existing codes and needed improvements.