This study presents a control scheme of the electronic interface of a grid connected Variable Speed Wind Energy Generation System (VS-WEGS) based on a Permanent Magnet Synchronous Generator (PMSG). The proposed system consists of wind turbines (WT) and 2 PMSGs connected to the electric network by back-to-back Voltage Source Converter (VSC) with a common dc-link. The generator-side converters are employed to attain Maximum Power Point Tracking (MPPT). The grid-side regulator controls the reactive power flow, the voltage at the dc link between both sides and the power factor during wind variations. The reliability and effectiveness of wind energy is shown to be depending on the applied control strategy. So, the control schemes are based on Sliding Mode Control (SMC) for control of both generators and grid-side converters of a VS-WEGS. The performance of the system has been demonstrated under varying wind conditions and under a grid voltage dip. The proposed SMC strategy is compared with the conventional Vector Control (VC) method. The simulation results show a good performance of the proposed sliding mode control.