The Research On Control System Of Variable-Speed Constant-Frequency Wind Power Conversion Using AC Excited Generator

Now, energy sources consume is increasing daily and environment pollution become more serious gradually. Because of its stand out merits, wind power is paid great attention in the exploitation of renewable energy source. The wind power generation technology has become the research hotspot of many country's scholars. The wind power generation system with variable-speed constant-frequency (VSCF) can capture energy as much as possible. AC excited generator can improve the stability of electric power system, its rotor speed may adjustable and it has ability on adjusting alone of the active and reactive power.The research status of wind power generation technology and VSCF technology are summarized in this paper. All kinds of excitation control strategies for VSCF generator and future trends are reviewed. According to power relationship and the demand of AC excited generation system, it put forward and designed a dual PWM converter with the capacity of energy bi-directional flow. It also analyzed the basic theory and mathematical model of three-phase voltage source PWM rectifier. Simulation results show that the converter can satisfy the demand of AC excited generation system, such as low harmonic, high power factor, fast dynamic respond and energy bi-directional flow. After studying the mathematical model in static three-phase coordinate and in rotary two-phase coordinate, the stator field-oriented vector control strategy is issued. The process of active and reactive power regulating is analyzed. It did a series of experimental study including connecting to power network and the adjusting alone of the active power and reactive power. The results of simulation validated the validity and feasibility of model and control strategy.However, because the mathematical model of the AC excited generation system is complex, non-linear, time changing and coupling, and it is strongly affected by the varying parameter and exterior disturbing. The control performance of traditional PID controller is restricted. Thus, fuzzy control is introduced, and a stator field-oriented vector control system based on the fuzzy controller is presented in this paper. Compared with the simulation results of two systems, the fuzzy controller has better dynamic performance, smaller still difference, and it converges rapidly. The ability of robustness has been improved greatly.