Small-Signal Modeling and Controller Parameters Tuning of Grid-Forming VSCs with Adaptive Virtual Impedance-Based Current Limitation

The adaptive virtual impedance (VI) control emerges as an attractive solution to limit the current of grid-forming voltage-source converters (GFM-VSCs) during grid faults. Yet, the adaptive VI-based current limitation relies on the detection of the current magnitude, which introduces nonlinear dynamics that challenges the controller parameters tuning of GFM-VSCs. This article develops the small-signal model of GFM-VSCs with adaptive VI-based current limitation, from which, the dynamic impact of the adaptive VI is explicitly revealed. Considering such impact, a holistic controller parameters tuning method for GFM-VSC is proposed to guarantee the small-signal stability of the system. Simulation and experimental tests are performed to verify the effectiveness of the theoretical analysis and the proposed parameters tuning method.