A Novel Fault Severity Factor based Protection Strategy for the Inverter-based Distribution Networks Considering System Strength

The Point of Common Coupling (PCC) serves as a hub for connecting various Inverter-Based Resources (IBRs), interconnected network grid, and loads. Designing a protection strategy for the faults that occur near the PCC is critical for the sake of maintaining connections of IBRs as per grid codes and preventing the system from the verge of transient instability. In contrast to existing methods, the proposed protection strategy offers a pragmatic approach to determine the fault severity. It considers not only faulty conditions but also pre-fault states, providing a holistic view of system dynamics. Additionally, it introduces self-tuned relay protection characteristics that dynamically adjust sensitivity and selectivity, considering standard voltage tolerance levels and changes in the system strength. Moreover, the suggested strategy integrates low voltage ride-through limits of connected IBRs in the protection characteristics, facilitating fault clearance without unduly disconnection of IBRs. Through detailed modeling and IBR controls simulated on the Matlab platform, efficacy of the proposed strategy is demonstrated across various pre-fault and faulty conditions, showcasing its adaptability and secure protective relaying performance.