I. Introduction
Microgrids are becoming an increasingly popular topic for both academic and industrial society [1]. The advances in power electronics technologies have lead to significant decrease in renewable generation costs which inspired discussions about splitting the existing distribution grids into autonomous systems. Subsequently, there have been a significant progress in development of control architectures for power electronics-interfaced generation allowing for flexible microgrid operation [2], [3]. It was soon realized that control methods that were standard for large scale power systems have rather limited applications in microgirds due to stability constraints [4]. Moreover, modelling approaches (ex. modelling based on time-scale separation) routinely used for conventional power systems appeared to be inadequate for microgrids, which demands for new modeling techniques to be developed [5].