Research On The Variable Speed Variable Pitch Control Of Wind Turbine

Traditional fossil fuels,while promoting socio-economic development,are destroying the earth's environment on which we live.In the face of traditional energy depletion and severe environmental problems,the development of renewable energy is one of the effective ways.Wind power has been widely concerned and developed in recent years.However,due to the strong nonlinearity of the wind turbine and the complexity of the operating environment,it is difficult and challenging to design the controller of the whole wind turbine system.The additive state decomposition(ASD)method,which can simplify the complex wind turbine system into two subsystems and simplify the analysis of the original system,is utilized to analyze the wind turbine and design the controller.Firstly,the basic structure and classification of the wind turbine are introduced and wind turbine models including wind speed model,wind turbine model,generator model,transmission model,and pitch actuator model are established.Then the operating principle and operating region of the wind turbine is analyzed.With rated wind speed as the boundary,the control strategies of wind turbine are divided into variable speed control and variable pitch control.Meanwhile,based on the control theory,the objectives and strategies are analyzed.Secondly,for the low wind speed,the variable speed controller based on the ASD method is designed to control the torque of the wind turbine.The original control problem is decomposed into a tracking problem of a linear time-invariant primary system with parametric uncertainties and external disturbances and a stabilization problem of nonlinear secondary system.Then the dynamic inverse controller and the backstepping controller are designed respectively.The controller of the original system is obtained,which reduces the difficulty and complexity of the analysis of the original system.Finally,the simulation results show that the controller can adjust the rotor torque according to the wind speed,obtain the maximum utilization rate of wind energy and realize the goal of maximizing the power output,the validity of the controller are verified.Finally,for the high wind speed,a nonlinear PI pitch controller based on the ASD method is designed to control the pitch of the wind turbine.For a wind turbine with uncertain parameters,external disturbance and input saturation,a nonlinear compensation controller is designed.Then,the additive decomposition method is applied to solve the problem of saturation and perturbation in the model and a PI form controller is designed,with above two sub-controller the pitch controller is obtained,which ensure the stability of the wind turbine with input saturation and improve the system response speed and operating range.The simulation results show that the controller can maintain the stability of the system and adjust the pitch angle with the wind speed to achieve the stable output power whether there is output saturation.The validity of the controller is indicated.