Integration of renewable energy sources into the power grid has become a critical research topic in recent years. Microgrid technology has emerged as a promising option to integrate distributed generation and facilitate the widespread use of grid-connected renewable energy. However, ensuring appropriate power quality (PQ) in microgrids is challenging. High PQ is crucial for achieving energy efficiency and proper operation of equipment. This comprehensive review paper offers an overview of PQ issues in microgrids, covering various types of PQ disturbances, their key features, and the most relevant PQ standards. Additionally, it provides an extensive case study review of published research on PQ analysis of microgrid and renewable energy based systems. The key findings of each case study and their investigation method are emphasized. The paper also discusses in detail the different approaches and models employed in these studies to assess PQ issues. A wide range of microgrid systems is presented, featuring various sizes, configurations, topologies, and components, such as photovoltaic and wind systems, energy storage systems, and electric vehicles. Overall, the paper emphasizes the importance of maintaining high PQ in microgrids and provides a valuable resource for researchers and practitioners interested in this topic.

As the world moves toward greenhouse gas reduction, there is increasingly active work around Li-ion chemistry-based batteries as an energy source for electric vehicles (EVs), hybrid electric vehicles (HEVs) and smart grids. In these applications, the battery management system (BMS) requires an accurate online estimation of the state of charge (SOC) in a battery pack. This estimation is difficult, especially after substantial battery aging. In order to address this problem, this paper utilizes SOC estimation of Li-ion battery packs using a fuzzy-improved extended Kalman filter (fuzzy-IEKF) for Li-ion cells, regardless of their age. The proposed approach introduces a fuzzy method with a new class and associated membership function that determines an approximate initial value applied to SOC estimation. Subsequently, the EKF method is used by considering the single unit model for the battery pack to estimate the SOC for following periods of battery use. This approach uses an adaptive model algorithm to update the model for each single cell in the battery pack. To verify the accuracy of the estimation method, tests are done on a LiFePO₄ aged battery pack consisting of 120 cells connected in series with a nominal voltage of 432 V.

DC microgrids are revolutionizing energy systems by offering efficient, reliable, and sustainable solutions to modern power grid challenges. By directly integrating renewable energy sources and eliminating the inefficiencies of AC-DC conversion, these systems simplify energy distribution and enhance performance in critical applications such as data centers, electric vehicle charging, and telecommunications. This review paper comprehensively examines the design, implementation, and performance of DC microgrids in real-world settings. Key components, including distributed energy resources (DERs), energy storage systems (ESSs), and control strategies, are analyzed to highlight their roles in ensuring reliability and operational efficiency. This review also explores the challenges facing DC microgrids, such as stability issues, protection mechanisms, and high initial costs, while offering insights into advanced control strategies and modular designs to overcome these obstacles. Through an evaluation of global case studies, this article bridges the gap between theoretical research and practical deployment and also demonstrates how DC microgrids can enhance energy efficiency, support sustainable power generation, and provide resilience in various applications. The findings highlight the potential of DC microgrids as a cornerstone of future energy systems, enabling clean, reliable, and decentralized energy solutions.

In remote areas, extending a power line to the primary electricity grid can be very expensive and power losses are high, making connections to the grid almost impossible. A well-designed microgrid that integrates renewable energy resources can help remote areas reduce investment costs and power losses while providing a reliable power source. Therefore, investigating the design of an independent and economically practical microgrid system for these areas is necessary and plays an important role. This paper introduces a design procedure to design an isolated microgrid using HOMER software (HOMERPro 3.14.5) for remote areas. In Vietnam, due to the obstruction of the mountainous terrain or the isolated island location, many remote areas or islands need electrification. A simple case study of a hybrid system with a 60 kW peak load demand on Con Dao island in Vietnam is used to illustrate the proposed design method. Specifically, a hybrid system that includes a PV system, batteries, and a diesel generator is designed. To provide the full information of the designed hybrid system designed, each solution is analyzed and evaluated in detail according to the sensitivity parameters.