Individual pitch control is an innovative technique in wind turbine control. It has the potential of reducing the asymmetric mechanical loads on the blades in large multi-megawatt turbines. As the mechanical fatigue is reduced, the lifetime of the turbine can be significantly extended. This work develops an individual pitch control for the National Renewable Energy Laboratory’s (NREL) 5 MW reference wind turbine. The individual pitch controller works along with a collective pitch controller, designed using Quantitative Feedback Theory (QFT) robust control. Simulations of the complete individual and collective pitch control system are conducted with the NREL’s computer-aided engineering tool for horizontal axis wind turbines (FAST). They show that the addition of the individual pitch controller significantly reduces the loads on the tilt and yaw directions in the nacelle and tower of the turbine at 1P and 3P frequencies, and on the blades at the 2P harmonic frequency.

This paper presents an experimental methodology to test and validate two Maximum Power Point Tracking (MPPT) strategies on variable speed wind turbines. The first technique of this study is an Extremum Seeking (ES) control strategy which does not require any wind turbine model or wind speed measurements. The analysis shows that its convergence can be quite slow in some cases. For this reason, we improve the ES control with a specific inner-loop that speeds up the convergence of the strategy. Additionally a conventional Perturb and Observe (P&O) algorithm is also implemented for comparison purposes. The proposed ES strategy with an additional inner loop controller shows fast tracking capability and high stability under both constant and variable wind speed in simulations and experiments. Both approaches are verified in Matlab simulations and experiments with a lab-scale wind turbine and a fully instrumented wind tunnel at CWRU-CESC.