The Microgrid (MG) concept as an important block of future smart electric grids provides a quite appealing solution for integrating renewable energy sources (RESs) into power grids. The increasing interest in penetrating of renewable energy power into the power system among the MGs highlights the importance of these systems and addresses serious challenges in MGs design and operation. The conventional modeling, analysis and control synthesis methodologies are usually suitable for high voltage traditional power grids; however, they may not be straightly applicable to the MGs that are operating in medium and low voltage levels. Control is one of the key issues in the MGs. Various control loops must be used to improve the MGs stability and performance. Current, voltage/amplitude, frequency/angle, and active and reactive power are the main feedback variables used in the existing MG control loops in both grid-connected and islanded operation modes. Like conventional power grids, the MG has a hierarchical control structure with different operation layers. The hierarchical control structure of MGs are responsible to provide proper load sharing and DGs coordination, voltage/frequency regulation in both operating modes, MG resynchronization with the main grid, operating cost optimization, and power flow control between the MG, neighborhood grids and the main grid. Advances in the MGs control improve the MGs potential to be integrated into the conventional electrical systems in a higher capacity. This improvement not only covers their internal control performance and connection/disconnection procedures in order to limit the negative dynamic impacts in the host network and other connected MGs, but also includes the grid support functionalities to enhance the global operation of distribution networks. MGs control techniques and management system make possible a new global planning strategy of power systems leading to a local economic optimization of electric energy with satisfied generation/load balancing and technical operation constraints (ancillary services) while participating to energy and service exchanges with surrounding stakeholders. This speech provides a brief coverage of MG dynamics understanding, control synthesis and realization. It covers the speaker`s long-term research, teaching and practical experiences on the MG control and operation. The materials given in the presentation are mainly the research outcomes and original results of Smart/Micro Grids Research Center (SMGRC) at the University of Kurdistan.
