Abstract
To reduce both the power output fluctuation and the platform motion, a feedback control algorithm based on blade pitch and generator torque manipulations for a spar-type floating offshore wind turbine-generator system was developed through numerical analysis using the aeroelastic simulation model (FAST), observed high wind speed data, and irregular sea waves. The blade pitch is collectively manipulated to maintain the generator power at a rated value, and the generator torque is manipulated to dampen the nacelle fore-aft motion. The concept of this control approach is to increase the generator torque in response to the platform motion to the leeward side and to provide a positive damping effect immediately to the platform motion. The numerical simulation showed the effectiveness of the generator torque manipulation and the filter of the nacelle fore-aft speed for the reduction in the platform motion. This feedback control approach had an advantage in not only the power output fluctuation and platform motion but also damage equivalent fatigue load characteristics over previous control approaches.
