As usual, the microgrid operates in grid-connect mode, but, when a fault occurs in the upstream grid, it should disconnect and shift into islanded operation mode. In grid-connect mode, the controlling power flow at PCC is necessary management function rather than the frequency and voltage. However, the controlling the frequency and voltage is asked in islanded mode. To achieve these management goals appropriately, the cooperative control strategy among microsources is needed. This supervisory control action is executed at MMS. In this paper, the management function of MMS is presented and evaluated by HILS test system and microgrid pilot plant. The proposed HILS test system was composed of the RTDS and a communication emulator. The RTDS performed real-time simulation of component models of the microgrid and the communication emulator simulated communication functions of components of the microgrid. The pilot plant consists of the PV, PV/Wind Hybrid system, BESS, diesel generators, and RLC loads. The test results show that the proper control strategy can ensure stability of microgrid in islanded mode and maintain the power flow of PCC at desired value successfully.