Optimal Ratio of Grid-Forming to Grid-Following Inverters Towards Resilient Power Electronics Dominated Grids

The modern paradigm of power electronics dominated grid (PEDG) has facilitated integration of grid forming (GFM) and grid following (GFL) inverters in the power systems. Addressing the potential disturbances in the PEDG will demand frequent reconfigurations including dynamic adjustment of these grid-interactive inverters' power contributions. However, such dynamic adjustments in GFM-GFL inverters' power contributions may in turn introduce stability issues. The optimal ratio of GFM to GFL inverters in a PEDG has not been well studied in literature with regards to system resiliency and reliable power delivery. This paper provides an analytical approach to determine the optimal ratio of GFM and GFL inverters to minimize their adverse dynamic interactions when subjected to severe disturbances. The main objective of this paper is to provide a comprehensive dynamic interaction-based analysis for a fleet of GFM and GFL inverters within a grid cluster and investigate the impact of inertia level emulated by these GFM inverters on the PEDG resiliency. The provided analysis is validated via several case studies in large-scale simulation representing a grid cluster with multiple GFM and GFL inverters.