Variable structure control for Permanent Magnet Synchronous Generator based wind energy conversion system operating under different grid conditions

This paper presents a nonlinear power control strategy for a grid connected Variable Speed Wind Energy Generation System (VS-WEGS) based on a Permanent Magnet Synchronous Generator (PMSG). The proposed system includes a wind turbine (WT) and a PMSG connected to the grid by back-to-back voltage source converter (VSC). The generator side converter is employed to control the speed of the generator with MPPT, and the grid side regulator controls the reactive power flow, the dc link voltage and the power factor during wind variations. The efficacy of the VS-WEGS can be greatly improved by using an appropriate control. So, this work explores a sliding mode control strategy to maximize the energy production of a VS-WEGS. The conditions for the existence of the sliding mode are found by applying Lyapunov stability theory. The performance of the system has been demonstrated under varying wind conditions and under a grid voltage dip. The simulation results show the effectiveness of the proposed sliding mode control.