Enhanced fault distance estimation for robust protection in unbalanced active distribution networks

Active Distribution Networks (ADN) have evolved significantly by integrating renewable energy sources. While these advancements have ushered in a more sustainable and efficient power system, these have also introduced challenges for traditional protection strategies. Conventional methods, often reliant on overcurrent relays, can struggle to adapt to the complexities of active distribution networks, where fault scenarios are diverse and dynamic. This paper identifies the limitations of conventional protection strategies and explores the redundancy concept applied to protection systems. To improve protection system reliability, an approach that overcomes these limitations using the advantages of distance protection is proposed here. The distance-based protection relay, traditionally employed in transmission networks, offers a promising redundancy solution for the challenges imposed by ADN. Considering the previous exposure, this paper introduces an algorithm for fault resistance and distance estimation designed to optimise the operation of distance relays in active distribution networks. The approach achieves remarkable accuracy with consistently low estimation errors for fault resistance and distance, regardless of fault type or distance. The proposed distance-based protection method is poised to revolutionise fault analysis in ADN, ultimately leading to faster fault isolation and more reliable and improved grid resilience.