| Double-fed wind power generator usually use double PWM converters for AC excitation.In response to the needs of double-fed wind power generator in practical engineering,this study has improved the control strategy of the traditional excitation system to improve its dynamics and robustness.The excitation system studied in this paper uses a two-level threephase voltage-type double PWM converter.The converter consists of a grid-side converter and a rotor-side converter,which are connected through a DC bus capacitor.The control algorithm for the grid-side converter ought to utilize a dual-closed-loop design,comprising an outer voltage loop and an inner current loop.In this paper,a combination of vector control strategy and first-order linear extended state observer control algorithm is proposed for the voltage outer loop,which is compared with the traditional vector control strategy and PI control.Both methods introduce space vector modulation technology and establish their respective mathematical models and control strategies.Finally,the grid-side converter models with voltage outer loop PI control and voltage outer loop linear extended state observer control inner loop PI control are built on the Matlab/Simulink platform for simulation comparison.The simulation results indicate that replacing the PI control with the optimized linear extended state observer control algorithm in the voltage outer loop of the grid-side converter yields a better performance,the overshoot of the DC bus voltage is smaller and the stable time is shorter.According to the simulation results,it can be concluded that the linear extended state observer control can effectively suppress the DC bus voltage fluctuation and has better robustness and adaptability than PI control.The control algorithm for the machine-side converter should adopt a double-closed-loop structure,incorporating a speed outer loop and current inner loop.This study suggests utilizing a combination of stator flux-oriented vector control and first-order linear extended state observer control algorithm for the speed outer loop,which is compared to the standard PI control.Both methods introduce space vector modulation technology and establish their respective mathematical models and control strategies.Finally,the machine-side converter models with speed outer loop PI control and speed outer loop linear extended state observer control inner loop PI control are built on the Matlab/Simulink platform for simulation comparison.The simulation results suggest that the use of the linear extended state observer control algorithm in the speed outer loop of the rotor-side converter results in faster and more accurate tracking of speed changes compared to PI control.After a disturbance,the system is capable of promptly restoring its stable state,and the designed control strategy can achieve the decoupling control of the machine-side converter.The control methods developed for the grid-side converter and machine-side converter were utilized in the double-fed wind power generator system.A comprehensive model of the system was established using Matlab/Simulink to validate the practicality of these techniques,which were then evaluated through simulations.The simulation outcomes demonstrate that the optimized linear active disturbance rejection control algorithm can attain variable-speed constant-frequency generation for the system.In addition,the rotor speed can swiftly trail the wind speed and attain the ideal speed that corresponds to the current wind speed.The control strategy of excitation system designed in this paper provides a theoretical basis and certain application value for improving the performance and efficiency of double-fed wind power generator.The improved excitation system control strategy proposed in this paper provides a certain theoretical basis and application value for improving the performance and efficiency of double-fed wind power generator. |
