Grid code compliant fault current limiting strategy for grid-forming inverter-based resource

Due to the limited overcurrent capability of grid-forming inverter-based resources(GFM-IBRs) constructed with power semiconductors, current limiting measures are required under grid faults. However, existing fault current limiting strategies for GFM-IBRs have not considered the grid code’s requirements for output reactive current during low-voltage ride-through (LVRT) stage. Additionally, these strategies underutilize the inverter’s overcurrent capability, thereby weakening the voltage supporting of GFM-IBRs. To address these issues, this paper proposes a virtual impedance-based fault current limiting strategy with positive/negative sequence decoupled. The virtual impedance values are dynamically calculated based on the terminal’s voltage and grid code’s requirements for output reactive current. Furthermore, the strategy evaluates the overcurrent risk of each phase and adaptively adjusts the reactive current ratio coefficients to optimize performance. Finally, PSCAD simulations validate the effectiveness of the proposed fault current limiting strategy.