IIT Microgrid (Optimal and Reliable Operation) Economic Operation Short-Term Reliability Tertiary Control Secondary Control Islanding and Resynchronization Grid Coordination Self-Healing Economic Demand Response Emergency Demand Response Control Monitoring Set Points Microgrid Components Coupling Switch at PCC Meters and PMUs Building Controllers Gas Turbines HRDS Switches Battery Storage Solar PV Primary Control Wind Turbine figure 2. Objectives and functions for the operation and control of the IIT microgrid. in island mode to supply its loads. But if the microgrid has been partly damaged during a natural disaster and has been deenergized along with other distribution system components in the restoration path, the microgrid master controller can quickly assess the damage situation and restore service to critical loads within the microgrid by utilizing local dEr units with black-start capability. Good coordination between transmission and distribution restoration procedures can enhance system reliability by increasing the amount of restored loads and reducing interruption times. islanded microgrids are capable of providing local self-healing and restoration services in a mediumvoltage distribution system. therefore, a conventional (and hopefully timely) strategy can be adopted for transmission system restoration while a quick and concerted service restoration at the downstream distribution level will allow the restoration of islanded microgrids equipped with local dEr units. in this context, the entire power system restoration can make use of a hierarchical approach that implements a conventional top-down procedure starting from the transmission 74 ieee power & energy magazine system as well as a bottom-up strategy starting from the lowvoltage distribution system and exploiting the capabilities of microgrids. the two systems (low-voltage microgrids and high-voltage transmission systems) will come together and be synchronized at the medium-voltage distribution level. in essence, a microgrid can assist distribution system service restoration processes by providing one or more of the following services: ✔ it can provide islanding from the grid for the local supply of microgrid loads and to reduce the supply provided by the utility grid. ✔ it can help coordinate the reduction of microgrid loads by providing an emergency demand response and curtailing noncritical loads in order to minimize the impact of outages on customers. ✔ it can increase its generation in order to supply local loads and, if possible, provide surplus generation to the utility grid. in order to achieve this, dispatchable dEr units (e.g., diesel generators and microturbines) can increase their dispatch by adjusting generation january/february 2014