Implementation of a robust control strategy for a large-power floating wind turbine

This paper introduces a new control strategy for large-power (25MW) floating wind turbines (FWTs). First, a robust nonlinear controller, an adaptive super-twisting (ASTW) approach, is employed. This method significantly reduces the modeling effort. The strategy is designed to address challenges such as the negative damping effect, which can occur beyond the rated wind speed. A traditional proportional-integral (PI) controller can mitigate this effect, but it is slow when applied to large FWTs due to the system’s small natural pitch frequency. Second, the proposed ASTW controller is compared with the ROSCO control, which is based on the traditional gain-scheduled PI controller. The simulations consider a complete aero-hydro-servo-elastic model of the system, including mooring lines, a floating platform, a tower, a generator, and a rotor. The results suggest that the ASTW controller can maintain good tracking of the rated rotational speed and power output while ensuring satisfactory platform stabilization and fatigue load reduction, thereby improving the overall efficiency of the FWT.