Enhancing Low Voltage Ride-Through Resilience in Grid-Connected Doubly-Fed-Induction-Generator with Sliding Mode Controller

In power systems, grid disturbances are prevalent, causing significant challenges for Doubly-Fed Induction Generators (DFIGs). During these disturbances, the windings of DFIGs are exposed to large offset inrush currents, which can damage the converter switches and capacitors. Additionally, low voltage faults result in a dip in the rotor speed, leading to current injection in the rotor windings at the changed rotor slip frequency during the fault. This behaviour can be detected using stator two-axis instantaneous voltage and flux. In this study, we propose an innovative application of Sliding Mode Control (SMC) in both the rotor-side converter (RSC) and grid-side converter (GSC) control schemes of a DFIG. The primary objective is to effectively control the flux decay and reduce torque pulsations, rotor speed variations, and current deviations through an enhanced SMC approach. The proposed technique compensates and rapidly decomposes the stator dc-offset flux component based on deviations in the speed of the rotor with the reference value and the dc flux. To assess the effectiveness of the proposed approach, we conduct a comparative analysis between the conventional Proportional-Integral (PI) control and the proposed SMC technique under symmetrical grid fault conditions. The results demonstrate the superior performance of the enhanced SMC in mitigating the adverse effects of grid disturbances on DFIGs.