Dr. YantingDr. John Council2026-05-202026-05-20https://dspace.academy.edu.ly/handle/123456789/2071this thesis presents a novel optimal OCR coordination scheme developed using the non-standard current characteristics (NSTCCs) approach. This approach is specifically designed to adjust OCRs. The proposed equation is contingent on a variable dynamic coefficient based on a logarithmic function curve for improving the flexibility of the curve, thus the optimal coordination between OCRs has been obtained throughout different fault modes.The operation of modern distribution networks (DNs) tackles serious challenges due to the integration of distributed generations (DGs). The protection scheme is one of these challenges. Particularly, the occurrence of bi-directional short-circuit current flow that affects the reliability, sensitivity and selectivity of traditional overcurrent relays (OCRs). In addition, the future distribution system with DGs is expected that will be occupied by the meshed networks alongside the classical radial design and alternating between the grid-connected and islanded mode, for enhancing their reliability.Radial and Meshed Power Networks