The Study Of Variable-speed Constant-frequency Doubly-fed Wind-power Generation System And Low Voltage Through Technology

Economic development needs the support of energy, China’s dependence on electric power is very serious. At present, people realize that thermal power can bring extremely harsh environment pollution and resource waste, wind power generation technology as a new energy technology is paid more and more attention. It not only can reduce resource consumption, also will not cause environmental pollution. Variable speed constant frequency(VSCF) Doubly-Fed Induction Generator(DFIG) because of its low cost, high efficiency, good support ability for grid, becomes the hot spot of research from various countries’ scholars. In this paper, the VSCF wind turbine control system and the low voltage through technology is studied, the main contents are as follows:Firstly, this paper outlines the research background of wind power generation technology. Based on the principle of VSCF wind power generator, and the study of mechanical properties and the tip speed ratio, it is concluded that the relationship between the wind energy utilization coefficient and tip speed ratio. it provides a theoretical basis for the analysis of maximum wind energy capture and variable speed constant frequency wind turbine torque speed characteristics. Secondly, this paper establishes a DFIG in the mathematical model of the two-phase synchronous rotating coordinate system by three-phase static to two phase rotating coordinate transformation. This paper establishes the decoupling control of active and reactive power of the double closed loop control scheme on the basis of research on dual PWM converter. Through the analysis of the topology structure of dual PWM converter and the mathematical model of three-phase PWM converter in the synchronous dq coordinate system, it is the basis of further research on coupled with current, power grid voltage feed-forward compensation control strategy. The simulation results of MATLAB/SIMULINK proves that dual PWM converter has the characteristics of good stability, high power factor, energy bi-directional flow, and studies the dual PWM converter under grid voltage fluctuation, and it has a certain guiding significance to software and hardware design of the actual system. Lastly, this paper analyses low voltage through technology, introduces low voltage through renovation project and the feasibility of low voltage according to my internship experience.The value of this research is through the design and simulation of DFIG control system, provides the theoretical significance for the subsequent hardware design, combined with the analysis of low voltage ride through the actual production experience.