Research On Control Technology Of AC Excitation Doubly Fed Induction Wind Power

Nowadays, energy sources consuming increased daily and environment pollution becoming serious gradually, wind power, as renewable, no pollution energy source, is paid great attention by more and more countries. Accordingly, wind power generation technology has become a research focus. In this thesis, the operation and control of variable speed constant frequency doubly-fed wind power generation system was studied with a comprehensively and deeply on theory analysis and simulation.Firstly, based on double-fed induction generator (DFIG) fundamental equation, the equivalent circuit and internal power relationship are analyzed in this paper, which established the theoretical base for the study. Then simulation models of generator under grid-connection based on the synchronous rotation coordinate system are built by using mathematics equations.Secondly, according to the features of doubly-PWM converter, and the mathematical model of DFIG in the two-phase rotating coordinate system synchronous, vector control strategies of DFIG is analyzed in the paper. The stator flux-oriented vector control technology is used on Rotor side converter to achieve decoupling control of active power and reactive power. The grid used voltage-oriented vector control technology is used to achieve grid side converter unity power factor and DC bus voltage constant. The simulation model in Matlab/Simulink is built up to complete the simulation analysis.Finally, according to the mathematical model of DFIG, the low voltage ride-through control of wind turbines under voltage dip is researched. And the steady-state response characteristics and transient response characteristics of DFIG are analyzed, regarding the deficiency of the control strategy the steady-state response of DFIG, a new control strategy is proposed and verified.