Research On Grid Connection Control Of Doubly Fed Wind Power Generation System Based On Linear Active Disturbance Rejection Control

Three phase voltage-type PWM converter has been widely used in variable speed constant frequency doubly-fed wind power generation system due to its advantages of low cast and small capacity.Vector controller is generally used in the control strategy.and the structurc of the double closed loop PI controller is used in the control algorithm to control wind turbine.However,the variable speed constant frequency doubly-fed wind power generation system is a inulti-variable,nonlinear and high coupling.Under the conditions of grid-connected voltage fluctuation and load disturbances,the linear PI controller has poor disturbance resistance of DC bus voltage based on the small signal model,large peak value of the rotor winding current of the doubly-fed induction generator and peak value of the stator winding current of the doubly-fed induction generator.This paper analyzes the interference resistance of doubly-fed wind power generation system with the vector controller andlinear auto disturbance rejection controller.This article built the simulation model of the system o"the Matlab/Simulink platform,studied and analyzed the disturbance resistance of the DC-bus voltage and the stator current characteristics of the doubly-fed induction generator under the two operating conditions of grid-connected voltage sag and electromagnetic torque increasc.Firstly,by studying and analyzing the steady-state and dynamic operation principles of the doubly-fed induction generator and converter,the mathematical models arc established respectively in the three-phase static coordinate system and the two-phase synchronous rotating coordinate system.Secondly,according to the control objectives of the doubly-fed wind power generation system,the control strategies and control melhods of the grid-side converter and rotor-side converter are analyzed and studied respectively.Based on the double-closed-loop PI control algorithm and rotor current-forward PI control method built on the Matlab/Simulink platform.Finally,the PI controller based on the small signal model has poor the perturbation resistance,which is replaced by LADRC.Under the condition of voltage fluctuation and torque increase,it is compared with the double closed-loop PI controller and the rotor current feed forward PI controller.The simulation results show that through linear state observer is used to estimate accurately and compensation for converter machine side load disturbance and network side power fluctuations,The system can effectively restrain the DC bus voltage fluctuation,control of the doubly-fed induction motor stator winding current peak.It has better adaptability,robustness and anti-interference than the performance of feedforward control and PI controller and the rotor current feed forward PI controller.