Adaptive Protection Coordination for Microgrids Using Dual‐Setting Directional Overcurrent Relays: A Real‐Time HIL Validation Approach

ABSTRACT Reliable relay coordination is critical for ensuring fast and selective fault clearance in modern power systems, particularly under the complex dynamics of microgrids operating in both grid‐connected and islanded modes. This research presents a robust protection coordination strategy using dual‐setting directional overcurrent relays (DS‐DOCRs) and a novel optimisation approach to address challenges in adaptive protection. A modified objective function, incorporating primary and backup relay operating times along with coordination time intervals (CTIs), was designed to enhance optimisation performance. The White Shark Optimiser (WSO) algorithm was employed to solve the coordination problem across IEEE 6‐bus and IEEE 14‐bus test systems. Short‐circuit analysis was conducted using DIgSILENT, while optimisation and implementation were carried out in MATLAB. Validation was achieved through hardware‐in‐the‐loop (HIL) simulation using the OPAL‐RT platform. The proposed method significantly reduced the total primary relay operating time from 12.38 s to 6.43 s (grid‐connected) and from 14.132 s to 9.738 s (islanded) in the IEEE 14‐bus system, and from 6.469 s to 4.820 s in the IEEE 6‐bus system. Compared to other metaheuristic methods, this approach demonstrated superior coordination performance and fault isolation capabilities. The results confirm the practicality and efficiency of the proposed adaptive DS‐DOCR scheme for improving microgrid protection reliability.