The Triple Spar campaign: Model tests of a 10MW floating wind turbine with waves, wind and pitch control

Results of three control strategies are reported: Fixed blade pitch, a standard land-based controller, and a tuned controller designed to eliminate the instability. Special rotor ID tests were carried out to characterize the rotor and identify the control parameters. Results for regular waves, focused wave groups, a wind-only test and irregular waves are presented in terms of time series, power spectra and exceedance probability plots. Among the key results are the wind-induced steady offset of floater pitch and surge and the aerodynamic damping of the floater pitch motion. Further, a clear example of the onset of unstable motion at the platform natural pitch frequency is provided along with a detailed analysis of the dynamic response for irregular wave conditions with the three control strategies. The paper ends with the first results of numerical re-modelling of the response for a waves-only test. A good match is found, thus encouraging further work in this direction.