Experimental Research On Rotor’s Excitation Control Of Doubly-fed Wind Power Generator

Among the various clean energy, wind energy possesses the greatest potential of development. Wind power generation is a good generation dispatching which can effectively cope with the environmental pollution and the shortage of energy, thus it has drawn a wide attention in the recent years. As a mainstream type at present, Doubly Fed wind power generator has the characteristics of flexible connection of mechanical-electric system, higher efficiency and smaller convertor. Besides, its rotor’s excitation control technology is a research emphasis in nowadays. This paper mainly focuses on the research of rotor’s excitation control of DFIG and the design of the convertor.First, the development status of the excitation technology and the application of the convertor in wind power generation are briefly narrated and induced, then the basic working principles and mathematical model of the DFIG is introduced. According to the principle of the equivalent magnetic field and power constant, the author illustrates itsmathematical model’s transformation from three phase coordinates to d-q coordinates and vector control strategy oriented by the stator flux, and elaborates on the theory and control algorithm of the Space Vector Pulse Width Modulation. Besides, the simulation realization of the SVPWM based on Per-unit statcom model is achieved under Simulink.Next, the structure and design of the DFIG experimental platform in the laboratory are introduced in detail.Besides, it was reconstructed. The Wind Turbine simulation drive unit, Rotor’s AC excitation unit, PLC monitoring unit and Data acquisition unit are described. Aiming at the problem of PLC’s slow sampling rate, the design method of a data acquisition device based on DSP is discussed.Finally, the generation of SVPWM based on Per-unit statcom model on the DSP is achieved and the calibration experiment of AD sampling is carried out. According to the actual circumstances, an excitation control method is proposed and rotor’s excitation experiment is conducted on the experimental platform, it turns out that the output voltage and frequency of the converter can be controlled respectively through the excitation methods used, thus can meet the basic control demand of DFIG.