On the definition of angle stability in power systems with grid-forming power converters

Abstract

This letter illustrates the paradigm that, in a power system with both synchronous machines and gridforming voltage source converters (GFM-VSC), the stability phenomenon related to the ability of generators to remain in synchronism when subjected to small or large disturbances would be part of two different stability phenomena at the same time: rotor-angle stability and converter-driven stability—slow interactions, according to IEEEPES classification. The letter presents a comprehensive analysis and it concludes that, stability phenomenon related to synchronism of generators in power systems with synchronous machines and GFM-VSC power converters can be understood as a single phenomenon and it proposes to use the term angle stability (instead of rotorangle stability) to refer to it. In order to make the proposed definition consistent with IEEEPES classification, the letter proposed excluding angle stability phenomenon from slowinteraction converter-driven stability.