Grid-Connected VSG Low-Voltage Ride-Through Control Based on Dynamic Current Limitation under Asymmetric Faults

In grid-connected photovoltaic (PV) power generation systems, maintaining operational stability under grid fault conditions is crucial for reliable performance. In practical power networks, asymmetric low-voltage faults occur more frequently than symmetrical ones. Therefore, PV systems are required to possess low voltage ride through (LVRT) capability to remain connected to the grid during voltage sags and to provide sufficient reactive power support for voltage recovery. To address the challenges introduced by negative-sequence voltage components during unbalanced grid faults, this paper investigates the LVRT control strategy for grid-connected PV inverters. The influence of asymmetrical voltage components on the system’s power angle, current, and power characteristics during faults is analyzed in detail. Based on this analysis, a dynamic current-limiting control strategy is proposed to enhance both the stability and dynamic response capability of the system. Simulation results under single-phase voltage sag conditions demonstrate that the proposed method effectively improves the LVRT performance of PV systems and contributes to more resilient grid-connected operation.