Modeling of a wind turbine driven dfig using variable voltage and variable frequency control for reactive power compensation under grid fault

This paper deals with the issue of the reactive power compensation in micro grid (MG) by changing the voltage based on Wind Turbine Generator driving a Doubly-Fed Induction Generator (DFIG). Wind generators such as the majority of Distributed Generation (DG) systems are sensitive to the disturbances of the voltage. Under voltage dip (sag) conditions, the induced rotor over currents of the doubly fed induction generators (DFIG) may greatly destroy the converter switches .These systems must to be disconnected in case of voltage sag, typically where the voltage is less than 80% of rated value. DG which contributes to reduce energy loss during transmission can increase the capability of the voltage control in the power system by generating the reactive power support. In this strategy we proposes to use two separate current control loops on the Machine Side Converter to supply additional active power during system frequency distortions and to reduce the transients in stator voltage after clearing the system voltage dips. In so far we have proposed the design of a current controller on the Grid Side Converter (GSC) to bring the system voltage level to the desired level during the system voltage sag condition. Then, the performances of both active and reactive power control of the DFIG under grid faults are analyse through Matlab/Simulink software.