Lyapunov‐Function‐Based Stability Region Estimation in Transient Stability Assessment of Inverter‐Based Resources: A Review

ABSTRACT

Electric power systems are undergoing a fundamental transition from synchronous generator (SG)‐dominated systems to inverter‐based resource (IBR)‐dominated systems. Lyapunov‐ and energy‐function‐based direct methods provide an effective way to estimate the stability region, also known as the region of attraction (ROA), and have become a fundamental tool for transient stability assessment (TSA). However, the fundamentally different large‐signal dynamics of IBRs make ROA estimation considerably more challenging, leading to a wide variety of Lyapunov‐function‐based methods. Motivated by these developments, this paper presents a methodology‐oriented review of Lyapunov‐function‐based ROA estimation for IBR‐dominated power systems. The review categorises existing methods into analytical and nonanalytical approaches, with the latter further classified into numerical Lyapunov, Lyapunov‐expansion and neural‐Lyapunov methods. For analytical approaches, the complete set of existing Lyapunov‐ and energy‐function constructions is reviewed and, where possible, extended to different IBR types. Nonanalytical methods are comparatively reviewed in terms of their underlying principles and scalability. The review clarifies the applicability of analytical and nonanalytical ROA estimation. Although systems containing grid‐following inverters generally do not admit a global energy function, heterogeneous systems composed of grid‐forming and voltage‐forming inverters remain amenable to analytical energy‐function‐based analysis. In contrast, nonanalytical methods provide broader applicability at the expense of substantially higher computational effort. Representative methods are reproduced and quantitatively compared in terms of conservativeness and computational complexity. The strengths and limitations of each method, practical engineering implementation and future research directions of the reviewed methods are finally summarised. This review provides a systematic reference for ROA estimation and its applications in TSA of IBR‐dominated power systems.