How to model a DC microgrid: Towards an automated solution

DC microgrids are envisioned to be EPDS (Electronic Power Distribution Systems) composed of COTS (Commercial-Off-The-Shelf) converters. Naturally, these converters will determine the dynamic behavior of the system. Besides, unlike classic EPDS, microgrids are highly variable due to the intermittent behavior of the renewable sources and customer consumption. In this context, there is not an accepted solution when it comes to create a model able to account for the large-signal dynamic behavior of the converters, their different operation modes or the interaction among them, which could lead to dynamic degradation or even instability. This work proposes the blackbox polytopic model as a tool able to accomplish these objectives. In particular, it is proposed a methodology to derive dynamic weighting functions using the characteristic polynomial of the transfer functions identified. Using this method, strong nonlinearities as transitions between operation modes can be represented more accurately and with a deterministic approach. This is a step forward towards the complex task of defining an automated tool able to model the particular phenomena that arise in dc microgrids.