Enhancing microgrid protection using dual-layer architecture and Battery Energy Storage Systems (BESS)

Conventional protection schemes face increasing difficulties as renewable energy sources and inverter-based resources (IBRs) contribute only limited fault current. This constraint frequently leads to slower fault detection, coordination issues, and reduced reliability, particularly during islanded operation. To address these challenges, this paper proposes two adaptive protection strategies: (1) virtual amplification of fault current through intelligent relay control and (2) active fault-current injection using Battery Energy Storage Systems (BESS). The strategies were implemented on the CIGRE benchmark network under three operating conditions, with OCR settings optimized using PSO, WCA, and TSA. Results indicate that TSA offers the best overall performance, achieving the lowest mean error and deviation (0.3–3.2) while maintaining moderate computation times of 9–12 s. It consistently outperformed WCA and PSO in accuracy, stability, and efficiency. Furthermore, total tripping times decreased substantially, most notably in islanded mode, where they fell from 49.35 s (SOCR) to 29.12 s and 32.56 s. To further evaluate the robustness of the proposed methods, an additional islanded high-impedance fault scenario with R f = 10 Ω is investigated, revealing that fault resistance has a limited impact on current levels due to the voltage-dependent behavior of inverter-based resources. These outcomes demonstrate the effectiveness of the proposed strategies in enhancing relay performance, reducing operating times, and improving the resilience of distribution-system protection.