Low fidelity modeling for the prediction of long-term floating offshore wind turbine performance

Floating offshore wind energy has been identified as a critical source of future sustainable energy. This work is part of
a broader effort to characterize the performance difference between floating and fixed offshore wind turbines. We characterize
the discrepancy between low fidelity blade element momentum
theory (BEMT) simulations and higher fidelity methods for floating turbines in the context of prescribed, harmonic platform motion. Five variations of a BEMT solver with varying empirical
corrections are compared to fully blade resolved computational
fluid dynamics simulations, as well as two experimental studies.
BEMT’s ability to predict rotor integrated parameters describing
the mean and fluctuating components of power and thrust is analyzed. We then utilize the BEMT method to predict the mean
and fluctuating component of rotor thrust and turbine power production under harmonic motion at frequencies of interest. The
BEMT method predicts small variations in the mean components,
but very large fluctuating components of power and thrust at
representative platform natural frequencies. Additionally, power
capture is predicted to increase at below rated wind speed and
decrease at rated wind speed during motion.