Enhanced LVRT control strategy for DFIG-based WECS in weak grid

An enhanced coordinated low voltage ride-through, LVRT, control strategy for a Doubly-fed Induction generator (DFIG)-based wind energy conversion system, WECS, connected to a weak grid is presented in this paper. The compliance with the grid code commitments is also considered. A proposed decoupled double synchronous reference frame (DDSRF) current controller is adopted for the design of grid side converter, GSC, controller to counteract current oscillations during asymmetrical faults and tackle the DC link voltage run-away. For a precise detection of the grid voltage position even under severe voltage dips/unbalanced conditions, A DDSRF-PLL is proposed and analyzed to extract clean synchronization signal in order to improve the overall system performance. Moreover, a fast decomposition based positive and negative sequence algorithm is utilized for rapid fault detection and to engage the LVRT protection scheme. Furthermore, additional compensation terms are incorporated with the traditional GSC and rotor side converter, RSC, controllers to effectively suppress rotor as well as stator currents and meanwhile regulate the rotor speed. A diverse set of voltage excursions are conducted to evaluate the effectiveness of the proposed control strategy using MATLAB/SIMULINK platform.