A survey on modeling of microgrids - from fundamental physics to phasors and voltage sources

TL;DR

This survey comprehensively reviews microgrid modeling, from fundamental physics to simplified models, highlighting the derivation process and physical insights behind common reduced-order models used in control design.

Contribution

It provides a detailed derivation of microgrid models starting from physics, clarifies assumptions behind reduced models, and offers a complete modular model of inverter-based microgrids.

Findings

Detailed dynamical models of microgrid components

Clear explanation of assumptions leading to reduced models

Complete modular derivation of a three-phase inverter microgrid

Abstract

Microgrids have been identified as key components of modern electrical systems to facilitate the integration of renewable distributed generation units. Their analysis and controller design requires the development of advanced (typically model-based) techniques naturally posing an interesting challenge to the control community. Although there are widely accepted reduced order models to describe the dynamic behavior of microgrids, they are typically presented without details about the reduction procedure---hampering the understanding of the physical phenomena behind them. Preceded by an introduction to basic notions and definitions in power systems, the present survey reviews key characteristics and main components of a microgrid. We introduce the reader to the basic functionality of DC/AC inverters, as well as to standard operating modes and control schemes of inverter-interfaced power sources in microgrid applications. Based on this exposition and starting from fundamental physics, we present detailed dynamical models of the main microgrid components. Furthermore, we clearly state the underlying assumptions which lead to the standard reduced model with inverters represented by controllable voltage sources, as well as static network and load representations, hence, providing a complete modular model derivation of a three-phase inverter-based microgrid.