RAFT Documentation
RAFT (Response Amplitudes of Floating Turbines) is a Python code for frequency-domain analysis of floating wind turbines. RAFT uses quasi-static and frequency-domain models to provide efficient computations of a floating wind system’s response spectra accounting for platform hydrodynamics, mooring reactions, rotor aerodynamics, and turbine control. It can be used to calculate response amplitude operators (RAO’s), power spectral densities, mean/static properties, and response metrics based on mean and root-mean-square values of each output.
Three reference designs represented in RAFT
RAFT serves as the lowest fidelity “Level 1” dynamics model in the WEIS (Wind Energy with Integrated Servo-control) toolset for control co-design of floating wind turbines. WEIS is a framework that combines multiple NREL-developed tools to enable design optimization of floating offshore wind turbines. See the WEIS documentation and GitHub repository for more information.
Following a modular philosophy, RAFT can be used independently for various frequency-domain modeling needs. Or, it can be used as an integrated part of WEIS through its OpenMDAO wrapper. The pages in this documentation site provide some guidance on setting up and using RAFT, as well as understanding how RAFT works. RAFT is available from the RAFT GitHub Repository and is released under the Apache 2.0 open-source license.
The following paper provides an overview of RAFT’s theory: