The Research On Doubley-fed Wind Turbine Control System And Converter

In the days of increasingly serious energy shortages and environmental pollution, as a renewable green energy, the development and utilization of wind energy is of great significance. In this regard, wind power technology has become a hot spot to researchers in all countries. The paper takes the running and control of the wind power system with AC excitation VSCF as the theme. It lucubrates the structure and running theory of the DFIG and carry through the decoupling control to active and reactive power of the DFIG with vector control. Based on the SVPWM and combined with logic pulse blockade principle, the paper puts forward the LVPWM technology and validates it's feasibility and advantage by apply it in dual PWM converter of the wind power system.It described the structure of the AC excitation VSCF in wind power system firstly and analyzed the running theory of the DFIG. On the basis of discussing with the DFIG math model and equivalent circuit, it researched the running characteristic and power relations which offers theory basis for the power control of the generator and the design of the excitation converter. Secondly, On the basis of discussing with the characteristics of the wind turbine and math model, it expatiates the theory of maximum wind power capture of the wind turbine. Also, it applies the technology of field oriented vector control to the DFIG and forms active/reactive power decoupling control strategy.Excitation converter is the key to realize the double-fed generator control, which is a decisive influence to control performance of the system and generator output power. Based on the operating characteristics of the AC excitation VSCF wind turbine, the paper designs the dual-PWM converter which has the functions of two-way flow energy, and it discusses the differences in the functions and control ways between the two converters. Network converter adopts the control of orientation vector control to the grid voltage and load current feedforward control technology based on power balance, it also realized the control of unity power factor of AC side and DC bus voltage. Machine-side converter using oriented vector control of DFIG stator flux, achieves the decoupling of generators P and Q. According to the different operating conditions on and under the synchronous speed of the generator, the two converters can be switched automatically between the rectifier and inverter (or inverter / rectifier) state, to realize two-way flow of the energy. Later, on the basis of SVPWM control technology, it elaborated the realization principle of the LVPWM and validated it's feasibility and advantages by Matlab simulation tool.Finally, we discuss a number of wind power systems low voltage operation (LVRT) problem. It analyze the doubly fed power generation system in the case of flicker model which provides a theoretical analysis of low pressure through the foundation for future research.