Abstract:

Doubly Fed Induction Generator (DFIG) is the most popular variable speed wind energy conversion system. Control of the DFIG is more complicated than the control of a standard Induction motor. To control the DFIG, the rotor current is controlled by a power electronics converter. This paper aims to analyze the performance improvement of DFIG with its controllers such as proportional integral, proportional integral derivative and fractional order proportional integral derivative controllers in micro grid. Design and implementation of these controllers are done in the rotor circuit of DFIG by MATLAB simulation tool. The design, analysis, and MATLAB simulation of a constant grid power wind energy conversion system also discussed. In all abnormal conditions, the required reactive power into the grid is taken care by the horizontal axis wind turbine system. Mathematical modeling of DFIG is addressed. Independent control of active and reactive powers is achieved, and different simulation results under loaded conditions, with variation in prime mover speed and Excitation are presented. The simulation results of the proposed system are discussed with the cases such as transient, post transient conditions, variation of wind speed, fluctuation of electromagnetic torque, active and reactive powers, grid voltage and load contribution of DFIG with its controllers in grid. Based on the extensive simulation results, what type of control scheme gives the effective performance of DFIG in grid is finally concluded. The performances of PID and FOPID controllers are compared with that of PI controller at the end. It is seen that, the closed loop performance of FOPID controller outperforms as compared to conventional controllers.

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