Power Quality in AC Islanded Microgrids: Technical Framework and State of the Art Review

Abstract

In recent years, operation and control strategies in distribution systems have changed due to the increase in the connection of distributed generation sources (DGs). Small local networks with electricity users and DGs are known as microgrids. These microgrids can operate independently (islanded) or in collaboration (interconnected) with the main network or other microgrids. Some advantages of interconnected microgrids include the reduction of losses, an increase in reliability, and decentralized operation under fault conditions. Nevertheless, when a microgrid operates in islanded mode, its electrical characteristics change and, consequently, the severity of power quality disturbances can increase, as well as their negative impact on electronic devices (loads and DG devices). This paper presents a comprehensive literature review of existing studies on power quality disturbances in islanded microgrids and identifies the most relevant needs for future research on this topic. Detailed information is analyzed to compare the differences between disturbance levels in both interconnected and islanded microgrids. In the case of harmonic disturbances, the impact of the different microgrid configurations is also analyzed.

Power Quality in Microgrids: A Critical Review of Fundamentals, Standards, and Case Studies

“…The Fourier transform is a valuable tool for analyzing these distortions, breaking down the signals into their constituent sinusoidal components at varying frequencies. Distortions can be classified into different types, such as harmonics, supraharmonics, interharmonics, subharmonics, notching, and noise [58]. The following subsections provide an overview of different types of these waveform distortions.…”

“…As described in [125] and [126], microgrids could experience PQ issues due to the increased penetration of non-linear loads and power electronics necessary to interface DERs. Phenomena such as voltage magnitude variation, voltage sags, swells, flicker, harmonics, unbalance, or natural and reactive power problems have been observed in microgrids and have been discussed in multiple papers [58]. Nevertheless, maintaining a high standard of PQ is crucial since disturbances can damage grid-connected equipment.…”

Design and Control of a Photovoltaic Distribution System Based on Modular Buck-Boost Converters

“…Several reviews on AC and DC microgrid operation, applications, modeling, and control strategies have been presented in the literature Shahgholian (2021); Dragi čevic and Li (2018); Quintero-Molina et al (2020); Gao et al (2019). An advantage of using these networks is that they provide more reliability to the system, since they allow power generation to take place closer to the load centers.…”