Current-based Virtual Impedance for LVRT capability in VSG for Predominantly Resistive Distribution Networks

This paper addresses the challenges posed to enhance stability of grid-connected Virtual Synchronous Generator (VSG) during disturbances in having Low Voltage Ride-Through (LVRT) capability during voltage sags. A novel current-based virtual impedance strategy is proposed, dynamically adjusting impedance based on the VSG’s output current, specifically considering both, the electromagnetic as well as the electromechanical stability of the system. Simulation results demonstrate superior LVRT performance compared to a fixed virtual impedance approach. Results are compared using indices like response time, response error, and maximum current per unit threshold.