This paper proposes a novel fault current suppression method for doubly fed induction generator (DFIG) low voltage ride through (LVRT) improvement employing modular multilevel converter (MMC). It is based on the inherent MMC arm impedance and the number of levels to provide transient damping of DFIG rotor and stator currents under severe grid faults, contributing effectively to maintaining the DFIG connection while ensuring controllability by avoiding the protection activation. Neither additional hardware nor control loops are necessary. DFIG dynamic equations under LVRT, including the contribution of the MMC, are presented, and a model is derived for control design. Performance assessment, including symmetrical and asymmetrical fault scenarios for MMC with 3, 21, 51, and 101 levels and comparison with existing and proposed controllers, highlighted that arm impedance and increased MMC level number contributed to DFIG stator and rotor fault current suppression, providing DFIG LVRT improvement under severe grid fault conditions.

New grid-connected systems have imposed additional requirements regarding reliability, power quality, high levels of power processing capacity, and fault support, where power converters have a crucial role in fulfilling these requirements. Overcoming one of these challenges, this paper proposes a new alternative application to improve the low-voltage ride-through (LVRT) support based on the arm impedance employment of the modular multilevel converter (MMC) by attenuating the fault impacts, avoiding overcurrents and overvoltages. This proposal does not require additional hardware or control loops for LVRT support, only using PI controllers. This paper evaluates symmetrical and asymmetrical grid fault impacts on the converter DC side of four converter topologies: two-level voltage source converter topology (2L-VSC), neutral point clamped (NPC), MMC, and 2L-VSC equipped with a DC-chopper, employing the same control structure for the four topologies, highlighting that the MMC contributed better to LVRT improvement under severe grid conditions.