Microgrids Operation Based on Master-Slave Cooperative Control

Low-voltage microgrids can be seen as the basic tiles of the smart grid patchwork owing to their capability to efficiently manage the distributed energy resources (DERs) in aggregate form. They can support the grid in terms of demand response, power quality, ride through capability, and at the same time, they can ensure electrical continuity to the loads, even in case of grid failure. This paper describes a simple and effective approach to manage microgrids by synergistic control of the power electronic interfaces acting therein, i.e., the utility interface (UI), installed at the point of common coupling with the utility and the energy gateways (EGs), interfacing the DERs with the distribution grid. The proposed master-slave control uses the UI as control master for the EGs. In grid-connected operation, the UI performs as a grid-supporting unit and dispatches active and reactive power references to the EGs so as to improve energy efficiency and power quality; in islanded operation, the UI performs as a grid-forming voltage source and ensures the power balance by exploiting every power source and energy storage unit available in the microgrid. This paper discusses the theoretical background, architecture, and algorithms of the proposed master-slave control and demonstrates the resulting microgrid performance by means of simulation and experimental results.