Title: Ensuring Disturbance Rejection Performance by Synthesizing Grid-Following and Grid-Forming Inverters in Power Systems

Abstract: To meet the dynamic requirement of power systems, it is imperative for grid-connected inverters to ensure good disturbance rejection performance (DRP) under variable grid conditions. This letter discovers and theoretically proves that for the general networks, synthesizing grid-following (GFL) inverters and grid-forming (GFM) inverters can more effectively ensure the DRP of multiple inverters, compared to homogeneous inverter-based systems that solely use either GFL or GFM inverters. The combination of GFL inverters and GFM inverters can concurrently increases the smallest eigenvalue and decreases the largest eigenvalue of the grounded network Laplacian matrix. This can be equivalent to rematching the proper short-circuit ratio (SCR) for GFL and GFM inverters, thereby ensuring the DRP of inverters both in weak and strong grids. The result reveals the necessity of synthesizing diverse inverter control schemes from the network-based perspective. Sensitivity function-based analysis and real-time simulations confirm the effectiveness of our results.