Sensitivity Analysis of Limited Actuation for Real-time Hybrid Model Testing of 5MW Bottom-fixed Offshore Wind Turbine

The present paper studies the effect of limited actuation for real-time hybrid model testing (ReaTHM® testing) of a bottom-fixed offshore wind turbine in operational, parked, and fault conditions. ReaTHM® testing is a new approach for conducting small-scale experimental campaigns and has recently applied to test a braceless semisubmersible floating wind turbine in MARINTEK ocean basin [1, 2, 3]. The aerodynamic loads on the wind turbine were applied based on simultaneous simulations coupled to the experiments while the wave loads and floater response were physically tested. The effects of actuation limitation on the ReaTHM® testing setup for the semisubmersible wind turbine were investigated previously [4] using numerical simulations, by not including some components of the aerodynamic loads or by inducing error (for example in the direction of the force actuation). In this paper, the same approach is used to investigate the sensitivity of a bottom-fixed 5MW offshore wind turbine to limited actuation. The consequences of limited actuation are also considered for fault conditions (grid loss, and blade seize with and without shutdown) due to the potential importance of fault events for the ultimate and accidental limit state analysis. For the operational turbine, most responses of interest were not strongly dependent on the studied limitations in actuation, but the aerodynamic pitch and yaw moments were important for fault cases.