A Comprehensive Review on Microgrids and Distributed Generation: Architecture, Control Strategies and Applications

Abstract

The increasing penetration of distributed generation (DG) technologies, combined with growing demands for resilient and sustainable power systems, has positioned microgrids as a transformative paradigm in modern electrical networks. A microgrid is a localized cluster of distributed energy resources (DERs), storage systems, and controllable loads that can operate in both grid-connected and islanded modes, thereby enhancing flexibility, autonomy, and reliability. By integrating renewable-based DG, microgrids mitigate intermittency challenges, improve peak demand management, and contribute to decarbonization, energy efficiency, and cost optimization. This review synthesizes state-of-the-art research on microgrid architectures, control strategies, and applications, emphasizing the critical role of design in ensuring stability and interoperability in converter-dominated environments. Architecturally, the study examines AC, DC, and hybrid microgrids configured in radial, ring, and meshed topologies, highlighting their relative strengths, limitations, and domains of application. The discussion extends to power electronic interfaces, particularly the roles of grid-forming and grid-following inverters in synchronization, harmonic mitigation, black-start capability, and fault tolerance. Communication infrastructures are highlighted as essential enablers of scalable and cyber-secure coordination. Control strategies form the operational core, where hierarchical approaches primary droop and virtual synchronous machine models, secondary voltage–frequency restoration, and tertiary economic dispatch—are evaluated alongside advanced methods such as predictive, adaptive, robust, sliding mode, and consensus-based controls. Protection and cybersecurity emerge as critical challenges due to low fault currents, bidirectional power flows, and digital vulnerabilities, necessitating adaptive relays, intelligent fault detection, islanding identification, and intrusion detection systems. Real-world applications across rural electrification, campuses, industries, defense installations, healthcare, and EV charging ecosystems are reviewed, with attention to techno-economic considerations such as lifecycle costs, CAPEX, OPEX, and resilience valuation. Finally, open challenges and research opportunities are identified, including interoperability, AI-driven predictive management, uncertainty modeling, and market design for DER integration. The review provides a holistic foundation for designing robust microgrids that advance the global transition toward reliable, sustainable, and low-carbon energy systems.