This work proposes an enhanced Low-Voltage Ride Through (LVRT) nonlinear control of Doubly Fed Induction Generator (DFIG)-based wind turbines under symmetric three-phase voltage dips in stiff grid conditions. Most of the control schemes that use rotor currents control for LVRT act on the stator flux by injecting reactive power into the grid so to re-arise the stator voltage to accepted values. Indeed, when the grid at the DFIG coupling point is powerful enough, the stator flux is no more controllable. This investigation first gives a mathematical model for the wind generation system besides a Backstepping control scheme for grid-connected DFIG powers flow control. Then, effects of a three-phase symmetric voltage dip are analysed and the reasons of rotor current surges, due to the voltage dip, and factors influencing it are inferred. As the stator flux is imposed by the power grid, this work proposes a Backstepping control for both converters to keep DFIG connected to grid within accepted values during faults. The rotor side converter keeps DFIG currents at nominal values and limits transients. The grid side converter keeps the voltage at DC-link stable. Results of these theoretical findings are verified by MATLAB/SIMULINK simulation on a 300 kW wind generation system.