With continuous technological advances, increasing competitiveness of renewable sources, and concerns about the environmental impacts of the energy matrix, the use of hybrid microgrids has been promoted. These generation microsystems, historically composed basically of fossil fuels as the main source, have experienced an energy revolution with the introduction of renewable and intermittent sources. However, with the introduction of these uncontrollable sources, the technical challenges to system stability, low diesel consumption, and security of supply increase. The main objective of this work is to develop an operation and control strategy for energy storage systems intended for application in hybrid microgrids with AC coupling. Throughout the work, a bibliographic review of the existing applications is carried out, as well as a proposal for modification and combination to create a new control strategy. This strategy, based on optimized indirect control of diesel generators, seeks to increase generation efficiency, reduce working time, and increase the introduction of renewable sources in the system. As a result, there is a significant reduction in diesel consumption, a decrease in the power output variance of the diesel generation system, and an increase in the average operating power, which ensures effective control of hybrid plants.

The reliability of energy supply is an important factor for end-users of electricity. Although many advances and efforts have been made by distribution companies to guarantee energy quality, weak feeders and grids are still usually found. As an alternative to minimize such problems, Battery Energy Storage Systems (BESSs) can be used to supply energy to users in the case of power outages or major energy quality problems. This paper presents test results on a real application scenario in a microgrid with different load configurations in the moment of interruption. The tests were compared to each other to analyze the impact found in each scenario. In addition to those, real unpremeditated cases of power quality problems were also discussed, and the performance of the utilized BESS was evaluated.

This paper presents the field deployment and operational evaluation of a hybrid photovoltaic–battery energy storage system (PV–HBESS) designed to enhance the resilience and energy autonomy of auxiliary services in a high-voltage transmission substation. The system integrates photovoltaic generation with two complementary battery chemistries, Lead-Carbon (PbC) and Lithium Iron Phosphate (LFP), managed by a dedicated energy management system (EMS). Installed at the 500 kV Messias substation operated by Eletrobras Chesf in Brazil, the microgrid architecture enables seamless transitions between grid-connected and islanded modes. Real-time field validation tests demonstrate the system’s capability to deliver uninterrupted backup power, perform demand control, execute energy shifting, regulate reactive power (Volt-Var), and smooth PV power fluctuations. Results confirm the effectiveness of the hybrid system in improving power quality and reliability under dynamic grid and solar conditions, making it a replicable solution for critical infrastructure support in transmission networks.