The Study On The Power Decoupling Of The Variable Speed Constant Frequency In Induction Generator System

The variable speed constant frequency (VSCF) wind generator is used widely in wind power system. To capture wind energy with high efficiency and improve power quality. Based on theory of nonlinear and the model reference adaptive technology, the decoupling control of DFIG is studied in this thesis. The main contents of the thesis are as follows.Firstly, a nonlinear decoupling controller is presented for DFIG based on nonlinear multi-input-multi-output state-feedback theory of differential geometry. By the nonlinear coordinate transform and state variable feedback control laws, the speed and rotor flux of DFIG can be decoupled completely. Secondly, using the stator flux-oriented vector control method, the decoupling of active and reactive power is realized and the controllers based on Internal Model Control theory is designed to improve the rotor voltage performance. Finally, by analyzing the mathematical model of DFIG and vector control scheme, an on-line adaptive estimators of stator flux and rotor flux, the rotor resistance and speed identification for DFIG are put forward in this thesis. The method is based on model reference adaptive principle. By using Lyapunov theory, the convergence of estimating error is proved. Based on the Matlab/Simulink, the simulation models of the system are developed, and the simulation results shown that the above scheme is feasible.