This paper deals with voltage and frequency control of a stand-alone wind energy conversion system (WECS) based on a double fed induction generator (DFIG) under wind speed and load variations. In this context, two kinds of linear and nonlinear control strategies, classical PI and backstepping, have been applied to the system in real time. A series of experiments have been conducted to evaluate and to compare dynamic performances of the proposed control approaches. Experiments on a 1.5Kw doubly fed induction machine in real time are carried out using dSpace DS1104 card based on the MATLAB/Simulink environment. Experimental results show the validity of implemented controllers and demonstrate the effectiveness, the precision and the rapidity of the backstepping control strategy compared with the PI controller.