Contents I. Introduction
The integration of power electronics-based sources is seamlessly achieved with the help of microgrids (MGs) as they offer the flexibility to enter or leave the grid [1]. MGs are typically composed of a renewable energy source (RES), an energy storage system, and several household, office, or industrial loads. Unlike the traditional grid, MG systems are generally equipped with a lesser share of conventional energy sources such as diesel generator systems [1], [2]. Recent studies indicate that the equivalent models of power electronic (PE) based RES, such as photovoltaic (PV) inverters, are typically highly capacitive or with resonance characteristics in harmonic frequencies as opposed to the highly inductive behavior of a conventional energy source [3]. In the case of an MG, since the PE-based sources are also capacitive or exhibiting resonance characteristics in addition to commercial PE-based loads, the interaction between the source and the various types of loads may lead to resonances in the frequency-dependent network impedance (FDNI) characteristics. Such resonance characteristics can cause adverse effects on voltage and current harmonics in the MG, similar to the effects of harmonic resonances in public low-voltage (LV) network [4]. Therefore, an analysis of the FDNI characteristics in an MG is needed.
