Adjustable Virtual Impedance via Anti-windup Method for Enhancing Transient Stability and Grid-Forming Capability Under Current Limiting Conditions

This letter presents a novel method to enhance the transient stability and grid forming (GFM) capability under current limiting conditions. The proposed method employs dual-loop vector voltage control with a back calculation anti-windup strategy, using adjustable gain to modify the X/R ratio of the equivalent virtual impedance. The method ensures seamless operation during transitions between normal and abnormal grid conditions while significantly improving transient stability and GFM capability. Theoretical analysis has been validated through 2 kVA scale experiments, demonstrating the effectiveness of the proposed method.