Fuse saving scheme in highly photovoltaic-integrated distribution networks

The high penetration level of photovoltaic (PV) units increases their injected fault current that it may result in fuse-recloser miscoordination in distribution networks. The conventional coordination techniques are based on shifting the fast operation curve of the recloser below the characteristic curve of the fuse for fuse saving in the case of a temporary fault. However, these techniques save fuse if the slopes of fuse and recloser characteristic curves are same. Also, in the case of the high penetration level of PV systems, the conventional schemes are not effective. To address these problems, this paper proposes two fuse saving strategies that not only modify the difference between the slopes of fuse and recloser characteristic curves but also are effective for various penetration levels of PV units in the distribution network. The proposed protection scheme does not require the communication infrastructure and can be implemented in both conventional and digital reclosers installed in the distribution network. The reliable performance of the proposed fuse saving strategies is assessed on the simulation model of the Isfahan distribution network.