On the other hand, the interest to renewable energies and distributed generation (DG, PV, wind) results in increasing number of installations not only because of its eco-friendly aspects but also its commercial advantages. Since the conventional relays including the OCR operate with fixed parameters (settings), it is difficult to ensure the proper protection operation when operating conditions of radial distribution system are changing as DGs connect and disconnect in the system. This problem becomes more serious if multiple DGs are connected to the system. In particular, the pre-determined coordination between the OCRs is affected by the increased fault current due to the connection of DGs and its reverse flow [1-4].