Microgrids protection: A review of technologies, challenges, and future trends

The proliferation of distributed generation, particularly renewable energy sources, has catalyzed the emergence of microgrids as a pivotal element in contemporary power system architectures. However, the integration of these sources introduces significant complexities in protection system design due to the inherent dynamic characteristics of microgrids, bidirectional power flow, and operational mode transitions between grid-connected or islanded states. Traditional protection paradigms, predicated on static fault current magnitudes prevalent in passive radial distribution networks, exhibit limitations in microgrid environments characterized by substantial fault current variability. Notably, constrained fault current contribution of inverter-interfaced DG units operating in current-limiting mode impedes the efficacy of traditional overcurrent protection. This necessitates the development of adaptive and intelligent protection methodologies. A hybrid microgrid simulation is employed to analyze fault current variations across diverse operational scenarios, underscoring the imperative for advanced protection strategies. This study evaluates the current state of microgrid protection, identifies existing research lacunae, and proposes potential future research directions to improve resilience, reliability, and security. This review examines various microgrid types, including AC and DC systems, with a focus on their operational conditions, configurations, and the diverse fault types they encounter in relation to different protection device frameworks. The study emphasizes the critical need for advanced protection technologies that are continuously evolving to address the increasing complexity of microgrid systems effectively. By presenting a comprehensive analysis of past advancements and future directions in microgrid protection, this paper aims to guide researchers and scientists, emphasizing the significance of their contributions in shaping the development and innovation of protection strategies in this essential domain.