Evaluation of directional relay algorithms in the presence of FCL

Integration of distributed generations into distribution systems has various impacts on power networks such as reconstruction of distribution networks and increase in short-circuit capacity. Reconstruction of distribution networks magnifies importance of detecting faults directions, which is relegated to directional relay. On the other hand, one of the most attractive approaches to mitigate the increased short-circuit capacity is utilising fault current limiters (FCLs). Since FCLs can drastically affect voltage and current signals during the first quarter cycle after fault occurrence and due to overlap between operation time of FCLs and directional relays, the affected voltage and current signals can lead to mal-operation of directional relays. To investigate this issue, performance of some well-known directional relay algorithms is investigated with and without the presence of FCL using plenty of simulations and some experiments. It is concluded that the FCL has different impacts on the investigated algorithms, so that some of them are not affected and some others are considerably affected.