Protection Design for Critical Microgrids

The deployment of energy management systems for microgrids depends on the specific need of each application and may consider various aspects such as technical, economic, and environmental. Regardless of the methodology and type of control, centralized or distributed, these systems aim to manage the operation of the microgrid, involving control strategies and logic for energy generation, storage, and consumption, ensuring efficiency and continuity in the energy supply. In this sense, this paper presents the control strategy implemented in a centralized energy management system of a critical microgrid operating in the Maranhao state of Brazil. This work explains the functionalities of the microgrid in both connected and isolated modes from the utility grid, specifically addressing technical aspects of each decision made when the communication network fails with different critical devices, such as protection relays and generation sources. Additionally, the coordination of protection adjustments, which are crucial for the safety and reliability of the microgrid, is discussed through analyses from protection curve adjustments. This coordination ensures that protection devices respond quickly and selectively to faults, minimizing impacts and maintaining the stability of the microgrid, allowing better integration with the main grid, as well as facilitating the detection and resolution of problems, such as short-circuits and power outages.