Dynamic Impedance Based Analysis of Microgrids

Abstract

Microgrids are networks of electricity users with local source of supply and able to operate independently from the external power system. This type of grids commonly integrate renewable energy based generation which are interfaced by means of power electronics devices. On this regard, the high penetration of this kind of technologies presents challenges in the stable and safe design of microgrids. For this reason stability analysis is proposed in this project considerating a microgrid with two types of converters. The procedure carried out to perform this task has involved the implementation of a microgrid model in simulink, derivation of the converters impedance models, integration of matrix transfer functions in a linear model and application of the Generalized Nyquist Criterion (GNC). The suitability of the GNC applied to microgrids has been assessed by investigating the stability limits of a study case. Specifically, a first stability limit has been found by increasing the number of grid following inverters that can be integrated, and then several parameters have been modified to enlarge the previous stability limit.