Ryohei Yokoyama

Gain-Scheduled Control of Blade Loads in a Wind Turbine-Generator System by Individual Blade Pitch Manipulation

A gain-scheduled control of the blade loads using individual blade pitch manipulation for onshore wind turbine-generator systems was developed to further reduce unbalance in the blade loads during rotation. The development was conducted through a numerical analysis of the NREL 5MW-onshore wind turbine-generator system using the aeroelastic simulation code (FAST) and the measured high wind speed data. In this control, the proportional gains for the blade load control are varied depending on the collective blade pitch instead of the inflow wind speed. The calculated signal for the individual blade pitch manipulation is superposed on the collective blade pitch signal to control the generator speed. First, the sensitivity of the proportional gains to variations in the blade thrust loads is analyzed to reveal the unique gain-scheduled rule. Then, the system performances, including the variations in the blade thrust loads as well as the generator speed and generator power, under the developed gain-scheduled blade load control are analyzed to demonstrate its effectiveness. The results revealed that the gain-scheduled rule considering the control stability has fine performances of the blade thrust load variations, as compared with conventional fixed-gain control and gain-scheduled control based on the stability limit as well as the collective blade pitch manipulation with no blade load control.