Stability Analysis of Multi-Inverter Systems with Heterogeneous Grid-Forming Dynamics

The dynamics of multi-inverter grid-forming (GFM) systems is highly complex due to the existence of many parameters and setpoints. Although the impacts of damping, inertia, a power reference, and current limiter are well understood in single-GFM systems, the same cannot be said for multi-GFM systems with heterogeneous parameters and setpoints. In this paper we examine the transient stability of multi-GFM systems and focus on the effects of power reference differences and virtual damping-to-inertia ratios on angle dynamics under fault conditions. Numerical results show that factors which enhance stability in single-inverter systems may produce destabilizing effects in multi-GFM setups. Our findings underscore the limitations of conventional stability assessment methods in multi-GFM environments and emphasize the need for tailored approaches to address complex interactions in inverter-dominated grids.