Optimal Control Of Output Power And Loads For Large-Scale Wind Turbines Based On Active Disturbance Rejection Control

The large-scale wind turbine leads to the increase of flexibility,the decrease of damping and the more complex dynamic loads of key components such as tower and blade.In order to stabilize the output power and reduce dynamic loads of the 5 MW variable speed variable pitch wind turbine,the research on the pitch control is studied.The research results were completed under the support of the National Key R&D Program of China,Key Component Optimization Design and Batch Manufacturing Process and Detection Technology of Drivetrain for Large Offshore Wind Turbines(No.2018YFB 1501304).The main research work and achievements are as follows:(1)The dynamic characteristics of the 5 MW variable speed variable pitch wind turbine are analyzed.The control objectives and technical requirements of each operation stage of wind turbine are summarized.Based on the theory of active disturbance rejection control,the characteristics,structure and design method of nonlinear active disturbance rejection controller and linear active disturbance rejection controller are compared and analyzed.The results show that the linear active disturbance rejection controller is more suitable for the pitch controller design of wind turbines.(2)In order to stabilize output power and reduce tower loads,the linear active disturbance rejection pitch controller is proposed.Based on the theory of active disturbance rejection control and dynamic equations of wind turbines,the discrete mathematical models of linear state error feedback and linear extended state observer are established.The rotor speed control loop and the tower damping control loop are designed,and the pitch controller model is built in Simulink.Through the overall identification and compensation of total disturbances,control performance of the wind turbine is improved.Compared with the traditional tower load controller,simulation results show that the output power and tower load fluctuation under turbulent wind condition are reduced by 1.9%and 7.2%respectively.(3)Focusing on the characteristic of aerodynamic imbalanced loads of wind turbines,the performance of the traditional PI individual pitch controller under aerodynamic imbalanced loads is analyzed.The traditional PI individual pitch controller is designed and built.Different degrees of aerodynamic imbalance conditions are simulated in GH Bladed software,and the power spectral density of blade root loads under PI individual pitch controller is simulated and calculated.Simulation results show that the traditional PI individual pitch controller has limited control effect on aerodynamic imbalanced loads.(4)In order to reduce aerodynamic imbalanced loads of wind turbines,the individual pitch controller based on linear active disturbance rejection control and resonance control is proposed.The model of the individual pitch controller is built based on active disturbance rejection control and resonant control theory.The controller parameters are designed.Taking the PI individual pitch controller as the baseline controller,the controller performance is compared and analyzed under various aerodynamic imbalance conditions.The simulation results show that the proposed controller can optimize the control effect of imbalanced loads.