Large Signal Lyapunov-Based Stability Studies in Microgrids: A Review

Microgrid stability studies have been largely based on small-signal linearization techniques. However, the validity and magnitude of the linearization domain are limited to small perturbations. Thus, there is a need to examine microgrids with large-signal nonlinear techniques to fully understand and examine their stability. Large-signal stability analysis can be accomplished by Lyapunov-based mathematical methods. These Lyapunov methods estimate the domain of asymptotic stability of the studied system. In this paper, a survey of Lyapunov-based large-signal stability studies of microgrids is given. Moreover, this paper covers large-signal studies of individual generator and load types in microgrid settings. Stability studies of dc/ac droop controlled inverters, ac/dc and dc/dc converters, and motor drives are explored. The survey shows that few large-signal Lyapunov-based studies have been completed on either individual systems or microgrid systems. This paper highlights the aspects that make Lyapunov-based microgrid stability studies interesting and valuable. This paper also recommends areas that future research could address to improve large-signal stability studies of microgrids.