Advanced multi-layer inverse-time relay scheme for enhanced arc-flash mitigation and coordination in distribution networks

• A novel objective function is formulated to minimise incident energy levels. • Integrating and employing TLBO algorithm. • An advanced multi-layer inverse-time scheme. This study presents an advanced multi-layer Overcurrent Relay (OCR) protection scheme designed to enhance relay coordination, reduce tripping times, and minimise arc flash risks in distribution networks. Traditional single-layer protection approaches often face limitations, particularly in modern grids that incorporate Distributed Generation (DG). To address these challenges, the proposed scheme employs a flexible, new multi-layer protection approach that enables relay settings to adapt according to the fault and network scenarios. The effectiveness of the advanced scheme is assessed through simulations on a modified CIGRE 14-bus and meshed power networks with various operation modes. Compared to conventional single-layer methods, total relay tripping times are reduced by up to 45.1 %, and incident energy levels decrease by more than 54 %, resulting in smaller hazardous zone requirements for maintenance personnel. These improvements are consistent across all scenarios, highlighting the scheme’s ability to adapt to various operating conditions and grid configurations, particularly as the share of renewable energy continues to increase.