Security enhancement in islanded dc microgrids via flexibility resources

This doctoral dissertation presents the research conducted by the author during the three-year Ph.D. programme (XXXVIII cycle) in Electrical and Information Engineering at olitecnico di Bari. The primary objective was to design methodologies and control strategies for energy management in DC microgrids, with a particular focus on fostering the development of stand-alone modern microgrids that integrate significant shares of intermittent renewable resources. Another key aim was to enhance the flexibility of isolated DC systems while ensuring secure and stable operation. The thesis provides a comprehensive analysis of islanded microgrid control and operation, addressing the behavior of grid components. Special attention was devoted to real-time power balancing through advanced actuators for grid management, flexible resources, and energy devices that operated via power converters, sensors, and other enabling smart grid technologies. Given the inherently low inertia of converter-based microgrids and isolated networks, the research also developed innovative solutions for providing fast voltage transient support services at the lowest hierarchical control level, operating on time scales of milliseconds to just a few seconds. The proposed methodologies demonstrably improve the reliability and stability of isolated DC systems, while also reducing operating costs and greenhouse gas emissions.