LQG/LTR robust control in variable-pitch variable-speed wind turbines

For the external input noise and internal measurement noise of the variable-speed variable-pitch wind turbine under practical conditions, the linear quadratic Gauss/loop transfer recovery(LQG/LTR) controller is designed to improve the wind turbine rotor speed and the tower fore-aft bending mode and to enhance the wind turbine system robustness under random disturbances. According to the disc and blade element theory of the wind turbine aerodynamics, the wind turbine torque and thrust are solved. Based on the linear model of the variable-speed variable-pitch wind turbine, the LQG and LQG/LTR controllers are designed respectively. The time curve of wind turbine rotor speed, tower displacement and pitch angle are simulated. Results show that the LQG/LTR controller can significantly improve the wind turbine system robustness and stability while achieving control objectives.