Research On Automatic Generation Control Method With Wind Power Participation

The contradiction between environmental protection and social development makes the promotion and application of clean energy represented by wind power having great significance to resource conservation,environmental protection and economic development.When wind power is connected to the grid on a large scale,due to the unique power decoupled operation mode of wind turbine,its rotor speed cannot respond to the change of grid frequency,which reduces the power grid frequency modulation ability;at the same time,with the increase of wind power penetration,the fluctuation of wind power also has an impact on the safe operation of the grid,which poses a greater challenge to the automatic generation control dominated by traditional thermal power units.In this paper,the power output control method of wind power participating in grid frequency modulation and the automatic generation control(AGC)method suitable for wind power participating in frequency modulation are studiedFirstly,based on the basic principle,structure,control strategy and goal of AGC system,the mathematical models of thermal power unit and wind power unit are elaborated in detail,and the interconnected AGC system model with wind power is constructed.Then,according to the control demand of wind power output when wind power participates in power grid frequency modulation,the paper analyzes the control mechanism of optimal power point tracking(OPPT)and pitch angle for wind power output adjustment.Based on the traditional OPPT,this paper puts forward the fast frequency response OPPT(FFR-OPPT)control method of wind turbine with superposition of two order derivatives of power system frequency.In addition,it can provide stable frequency support for the power grid by adjusting the pitch angle,and reduce the mechanical wear in the process of adjustment as much as possible.The integrated control method of the pitch angle and FFR-OPPT of the wind turbine is designed.The simulation of the single wind turbine frequency modulation shows the effectiveness of the proposed method.Thirdly,considering the uncertainty brought by large-scale wind power grid connection,the AGC control method based on predictive optimization two degree of freedom PID(PO-2-DOF-PID)is designed by combining predictive control method with two degree of freedom PID(2-DOF-PID)controller.On the one hand,the integration of 2-DOF-PID controller and predictive control model can effectively improve the processing capacity of AGC controller online optimization;on the other hand,the PSO algorithm is used to optimize the parameters of 2-DOF-PID controller,which can effectively improve the AGC control performance.Finally,based on the cooperative control of pitch angle and FFR-OPPT,as well as the predictive optimization of 2-DOF-PID controller,the AGC system with wind power participation is synthesized.Based on MATLAB / Simulink environment,a three areainterconnected AGC system is constructed to verify the AGC effect under the participation of wind power.The simulation results show that the proposed wind turbine output control method can extract the inertia of the wind turbine more quickly in the process of participating in AGC regulation,and has a better inhibition effect on the frequency offset;and the predictive optimized 2-DOF-PID controller can effectively improve the AGC regulation under the large-scale wind power access Frequency effect,better response to the uncertainty brought by wind power access.