Individual Pitch Control of a Large Wind Turbine Using a Fractional Order Nonlinear PI Approach with Anti-windup Strategy

In this contribution, an individual pitch control system (IPC) for a large wind turbine by using a fractional order nonlinear PI approach (FO-NPI) is implemented and its performance compared with the standard PI controller analyzed. A solution to the problem of the integrator wind-up in the case of the IPC is proposed, as well. It is considered that pitch actuators saturate not only in magnitude but also in rate. A 20 MW reference wind turbine, which is implemented in the simulation software OpenFAST, is used as virtual plant for the simulation experiments. Simulation results indicate that the IPC system based on the FO-NPI techniques improves the wind turbine control performance and reduces damage equivalent loads (DELs) by 7.5 percent on average when compared with classic PI control.