  The use of distributed generation resources, in addition to considerable
benefits, causes some problems in the power system. One of the most critical
problems in the case of disruption is increasing short-circuit current level in
grids, which leads to change the protection devices settings in the downstream
and upstream grid. By using fault current limiters (FCL), short-circuit
currents in grids with distributed generation can be reduced to acceptable
levels, so there is no needed to change the protection relays settings of the
downstream grid (including distributed generations). However, by locating the
FCL in the tie-feeder, the downstream grid is not more effective than the
upstream grid and thus its reliability indices also will be changed. Therefore,
this paper shows that by locating the unidirectional fault current limiter
(UFCL) in the tie-feeder, the necessity of changing in the relay protection
settings of upstream grids is prevented. In this paper, the proposed method is
implemented, and its efficiency is reported in six scenarios.
