Decentralized Stability Certificates in IBR-Dominated Grids: The Role of the Network State
It provides a more realistic stability assessment for grid operators by incorporating network state into decentralized stability certificates, addressing a key limitation of prior work.
The paper develops a decentralized analysis framework for small-signal stability in inverter-based resource dominated grids, showing that increased reactive power mismatches and line loading tighten admissible inverter droop gains, making stability certificates network-state dependent.
Small-signal instabilities, such as unforced sub-synchronous oscillations (SSOs), are increasingly observed in inverter-based resource (IBR) dominated grids. While decentralized stability certificates offer a scalable means to avoid instability onset, they are typically derived under restrictive network-state assumptions--such as small angle differences or negligible voltage drops--that cannot capture how departures from these conditions affect system stability. In this paper, we develop a network model and a decentralized analysis framework that explicitly characterizes how reactive power mismatches, line loading, and inverter control parameters jointly determine small-signal stability. We show that increased steady-state reactive power mismatches and line loading lead to more stringent conditions on admissible inverter droop gains. These results make decentralized stability certificates explicitly network-state dependent, showing how network stress shrinks the set of stabilizing local controller parameters.