Critical aspects of hybrid microgrids: Architectures, energy management, optimization techniques, and future research directions-A review

The increasing penetration of renewable energy resources has accelerated the development of hybrid microgrids as a key solution for enhancing the sustainability, reliability, and operational flexibility of modern power systems. However, the intermittent nature of renewable generation, the growing integration of distributed energy resources (DERs), and the increasing complexity of energy management require advanced control, optimization, and storage technologies. This paper presents a comprehensive critical review of hybrid microgrids, covering their architectural configurations, hierarchical control strategies, energy management systems (EMSs), optimization techniques, and hybrid energy storage systems (HESSs). A systematic methodology supported by PRISMA-based literature screening, bibliometric analysis, and a taxonomy framework is employed to ensure a transparent and structured evaluation of the literature. Comparative analyses are conducted to assess conventional and artificial intelligence (AI)-based control strategies, mathematical and metaheuristic optimization methods, and emerging HESS configurations in terms of efficiency, scalability, computational complexity, and practical implementation challenges. Furthermore, critical issues including communication latency, interoperability, cybersecurity, battery degradation, explainable AI, and uncertainty-aware energy management are comprehensively discussed. Based on the identified research gaps, future directions are proposed, emphasizing digital twins, federated learning, distributed intelligence, resilient cyber-physical architectures, and next-generation AI-driven energy management. This paper provides a comprehensive reference study for researchers and practitioners involved in the design, control, optimization, and deployment of intelligent hybrid microgrid systems.