| Power production is the most important form of energy consumption in the world today.Clean energy is an important topic of universal concern in the world today.It can effectively alleviate the environmental problems caused by the massive use of mineral resources.As a clean energy,wind energy has attracted much attention because of its large reserves,wide distribution and power generation.In this thesis,considering the influence of aerodynamic effect on wind turbines,a series of variable pitch control studies are carried out for a 1.5WM variable pitch wind turbine.On the basis of analyzing the basic laws of variable pitch control,a fuzzy PID and a pitch angle compensation control strategy based on iterative learning are proposed to improve the pitch angle control performance.The main work is summarized as follows:This thesis first summarizes the current situation of wind power generation and its related technologies,and also includes the research on improving the pitch control of wind turbines.Secondly,the basic components of the wind turbine,namely,the drive chain,the pitch drive unit,the generator,are described in detail,and the simulation models of each part are established.In addition,considering the influence of aerodynamic effect and natural wind characteristics,the wind speed model adopted in this thesis provides a theoretical basis for variable pitch control.According to the characteristics of wind turbine,a hybrid controller based on PID control and fuzzy theory is proposed in this thesis to realize the variable pitch control of wind turbine.The theoretical basis based on fuzzy control technology is given,and the corresponding control software is given.In order to test the working characteristics of the control system,a relevant model is built in Matlab/Simulink for simulation analysis.The results show that the pitch controller designed based on fuzzy theory has better control effect than the traditional PID controller under different wind conditions.According to the analysis of 2MW wind turbines with different installed capacity,the fuzzy pitch controller designed can still achieve good control effect under the premise of changing the mathematical model and parameters,which is consistent with the characteristics that fuzzy theory does not require accurate mathematical model,and its applicability is verified.Considering the trend of large-scale development of wind turbines,the shear wind effect is obvious due to the elevation of the rotating plane of the impeller.Combined with the characteristics of iterative learning theory,the controlled system model is built,and a new control law is proposed,that is,the open loop adopts D-type control law,and the closed loop adopts P-type control law.The corresponding pitch controller based on iterative learning is designed.Taking a point on the blade as a sampling point to simulate the shear wind,the simulation results show that compared with PID controller and fuzzy PID controller,this variable pitch controller can quickly track the desired speed,thus suppressing the periodic disturbance,and has better control performance;At the same time,the generator speed can be stabilized in a short time,and the power output can reach the desired value more quickly.At the same time,this thesis also carried out the simulation research of wind turbine under the simulated natural wind speed.The results show that the controller designed has better dynamic performance regardless of the wind speed interference mode,which is reflected in stabilizing the output efficiency of the wind turbine,reducing the speed fluctuation of the wind turbine,suppressing the periodic disturbance,reducing the impact on the power grid,and improving the stability and security of the whole system. |
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