Impact of Distributed Secondary Control on Transient Stability of Islanded Microgrids

In conventional power systems dominated by synchronous generators, transient stability was found to be less influenced by the secondary control (e.g., automatic generation control). However, due to the flexibility of control and communication of grid-connected converters, more advanced control schemes such as the virtual-impedance-based distributed secondary control can be applied to multi-converter islanded microgrids, which may have a significant impact on the microgrid’s transient stability. In this paper, a simplified model considering the essential synchronization dynamics is established, and the metric named microgrid stable basin is proposed to measure the impact of critical secondary control parameters on the transient stability. Finally, laboratory measurement is provided to verify the theoretical findings.