Fault Ride-Through Control Strategy of a VSG-Controlled Grid-Connected Inverter

With the accelerated evolution of new power systems dominated by renewable energy, the grid-connection control strategies and fault ride-through capability of converters have become crucial for ensuring secure and stable system operation. This paper first compares and analyzes the difference in response characteristics between grid?forming and grid?following converters under grid faults, clarifying the inherent reason why grid?forming converters, as voltage sources, face overcurrent challenges during voltage sags. On this basis, for a grid?forming converter adopting virtual synchronous generator control, a low?voltage ride?through strategy oriented to symmetrical voltage sags is proposed. The core of the strategy includes: employing virtual resistance to suppress steady?state overcurrent, and instantaneously adjusting active and reactive power commands in the same direction to suppress transient inrush current. Simulation and experimental results show that the proposed method can effectively limit the fault current within a safe threshold and consistently maintain the voltage?source characteristics of the grid?forming converter throughout the ride?through process, providing a feasible solution for the safe grid?connected operation of grid?forming converters.