Adaptive Virtual Impedance for Reactive Current Control during Fault Conditions in Grid-Forming Inverters

Grid-forming (GFM) inverters play a crucial role in modern power systems by providing voltage and frequency support and enhancing the inertia as more renewable energy sources are integrated into the power system. However, unlike synchronous generators (SG), GFM inverters have limited over-current capacity and require additional controllers to restrict their output currents during fault conditions. To address this challenge, this paper proposes a novel control technique that regulates the injection of reactive current into the grid based on the voltage drop. This approach aligns with recent grid codes that emphasize the importance of enhancing power system support during low-voltage ride-through (LVRT) conditions. By applying this technique, the severity of faults can be minimized, and power system stability and reliability can be significantly improved.