| The natural environment is gradually deteriorating,energy consumption is increasing rapidly,and the shortage of resources is becoming more and more serious.In order to cope with this global challenge,wind power generation technology has become a research hotspot of scholars from all over the world.With the maturity of wind power generation technology,the cost of wind power generation is also decreasing.This paper analyzes and studies the control strategy of the double PWM converter based on the doubly-fed asynchronous wind turbine of the energy storage device,and also conducts in-depth research on the grid-connected stability and the primary frequency regulation capability of the energy storage system.In this paper,the doubly-fed asynchronous wind turbine is first analyzed,the mathematical model of the dual PWM converter in the three-phase stationary coordinate system is established,and then the coordinate transformation theory is used to further establish the mathematical model of the dual PWM converter in the two-phase stationary coordinate system and the two-phase rotating coordinate system.On this basis,aiming at the problems of difficult to adjust parameters,poor adaptability and insufficient robustness in the traditional vector control of doubly-fed wind turbines,this paper proposes a PI-SMC-based controller by analyzing the mathematical models of machine-side converters and network-side converters from the perspective of the impact of wind speed mutations on the system.The control system combines the PI voltage control and the double-power exponential approach rate sliding mode current control to obtain a new controller that suppresses the DC bus voltage fluctuations of doubly-fed wind turbines.Improve the DC bus voltage immunity,enhance the control accuracy and smoothness,and provide support for the energy storage device.Secondly,the application of hybrid energy storage devices can smooth the fluctuation of distributed power output power and improve the absorption of large-scale power grids for wind power generation systems.According to the characteristics of rotation inertia and damping of traditional synchronous generators,by simulating the electromechanical transient equations of traditional synchronous generators in the control link of the converter,the excellent characteristics such as inertia,damping and primary frequency regulation of synchronous generators are transplanted to the fan,and virtual synchronous generator（VSG）technology is introduced.By configuring the energy storage device on the DC side of the wind power generation system and adopting the control strategy based on the synchronous generator model for the energy storage system,the influence of the parameters of the virtual synchronous machine on the system stability is analyzed to assist the system to achieve virtual inertia control under load disturbance,the amplitude of the system frequency oscillation is reduced,and the role of the system inertia to achieve frequency adjustment is finally discussed.Finally,according to the designed control block diagram,the simulation model of the doubly-fed wind power generation system based on the energy storage device is established by MATLAB/LIMULINK simulation software.The simulation results of applying PI control technology and PI-SMC sliding mode control technology are compared and analyzed.The results show that the designed PI-SMC sliding mode control strategy has the advantages of strong robustness,fast convergence speed and high tracking accuracy.At the same time,the designed VSG can effectively simulate the inertia response characteristics and frequency response characteristics of the actual synchronous generator.When the system is set with load disturbance,the virtual inertia control strategy can adjust its own output power according to the load fluctuation,effectively compensate the inertia of the grid,and quickly damp.The grid frequency changes,which improves the system frequency operation characteristics. |
PDF Full Text Request