A Networked Oscillators-Based Large Signal Stability Analysis for Grid-Forming Inverter Dominated MGs

With the increasing penetration of renewable energy, the integration of power electronic equipment has fundamentally re-shaped the dynamic characteristics of modern power grids. Due to the lack of support from the main grid, islanded microgrids (MGs) are prone to losing synchronization stability under large signal disturbances. Existing stability studies often focus on single-inverter systems, which have limited performance in multi-inverter scenarios due to the extended computational burden. Therefore, this paper proposes a method for evaluating the large signal stability of MGs composed of grid-forming (GFM) inverters based on the networked oscillator model. Firstly, the equivalent oscillator model of the GFM inverter is established to accurately characterize both the inherent and interactive dynamics of a single GFM inverter, thereby enabling the construction of a networked oscillator model for islanded MGs with a general topological structure. The large signal stability analysis of the system is then carried out analytically, and the frequency stability domain is explicitly derived. Finally, the effectiveness of the proposed method is verified through time-domain simulation and Controller Hardware-in-the-Loop (C-HIL) experiments.