Active Disturbance Rejection Based Pitch Control of Variable Speed Wind Turbine

Pitch system is a complicated nonlinear system disturbed by many uncertainties and is a key part of wind turbine system. When wind speed exceeds rated cut-in speed, pitch angle is changed to control wind power conversion efficiency, thus capturing rated power from wind and protecting wind turbine from damage. In this paper, based on the analysis of wind turbine aerodynamic, an active disturbance rejection based pitch controller for variable speed wind turbine is presented to improve performance of key turbine variables including pitch angle, turbine rotor speed, and power output. Based on turbine rotor speed feedback, an extended state observer is designed to estimate state variables and disturbances. To verify the performance of the proposed controller, simulations for different turbulent winds are carried out. Simulation results show high performance of proposed scheme for high-precision control of pitch angle.