navid Bayati - Department of Electrical Engineering , Amirkabir University of Technology, Tehran, Iran
s.H.H sadeghi - Department of Electrical Engineering , Amirkabir University of Technology, Tehran, Iran
amir hosseini - Department of Electrical Engineering , Amirkabir University of Technology, Tehran, Iran

Recently, distribution generation (DG) usage is widely increased which can have undesirable effects on power protection systems. DG usage will lead to change the levels of short circuit in the power system. Therefore, protection coordination of directional over-current relay (DOCR) may be lost. In this paper, using fault current limiter (FCL) to restore DOCR protection coordination has been discussed. For this purpose, appropriate FCL initialization and placement is so important. Also, genetic algorithm (GA) optimization method is used in this paper. Moreover, DG generated power variation can change the short circuit levels and changing in DG placement can cause DOCR miscoordination so that all DG placement situation as well as the different amounts of their production power should be considered. In DOCR protective coordination and FCL values optimization, DGs should be considered. Therefore, the proposed method will be robust when the DG values change. Also due to the economic problems, two different types of FCL are used. Thus, the optimization algorithms for each specific location suggest different FCL which can reduce the costs. The proposed method is implemented based on the IEEE 8-bus. The simulation results show that the proposed method can provide DOCR protection coordination in the presence of the DGs and their location and values variations. In other words, the proposed method should be robust.

FCL, DOCR, GA, Placement, DG