| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 104 === This thesis presents power mode control strategy with a Fuzzy proportional-integral(PI) controller in the rotor side converter of the doubly fed induction generator (DFIG). The proposed technique is employed to control the active and reactive power of wind turbine to the grid and reduces the overcurrent during the grid fault. The DFIG is operated at maximum power tracking mode in the steady state, and keeps operating at this mode to deliver power as much as possible during fault. However, it causes overcurrent problem in this operation.
In this work, the mathematical model of the power controller is developed by theoretical analysis for DFIG and employed to determine proper gain for the Fuzzy PI controller such that DFIG has fast response and good stability. Moreover, DFIG under power mode control delivers not only active power but also reactive power to boost the system voltage.
The MATLAB/Simulink® software is employed to develop the grid-connected DFIG model and evaluate the effectiveness of Fuzzy PI controller. The simulation results show that the Fuzzy PI controller enhances the dynamic performance and the rotor transient overcurrent can be suppressed during fault initiation. Moreover, DFIG under power mode control is able to decrease the steady-state rotor current during faulted period. Therefore, the rotor side converter can be protected by employing the Fuzzy PI controller for the DFIG operated under power control mode during the fault. Low voltage ride through capability of the DFIG can be enhanced by the proposed fuzzy PI controller.
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