In this research, an enhanced control scheme for the permanent-magnet synchronous generator (PMSG) wind turbines under grid voltage fault condition is introduced. The machine-side converter (MSC) controls the DC-link voltage
however, this voltage value can be still increased during the grid fault. Thus, the braking chopper (BC) added to the DC-bus will be activated to dissipate the surplur power between the grid and generator powers. Meanwhile, the grid active power is regulated at the grid-side converter (GSC), from which can be exploited to inject reactive current into the grid for assisting the grid voltage recovery.Also, an algorithm of positive-sequence current control in the dq-axis is implemented, basedon feedback linearization theory. The validity of this control algorithm has been verified by the simulation of the 2MW-PMSG wind turbine system.Keywords: Braking chopper, permanent-magnet synchronous generator, unbalanced voltage,wind turbine.