A Review on the Classification of Operating Modes in Microgrid Systems

A microgrid is an independent electrical system, and it integrates different energy sources to produce power independently or in coordination with the main grid. In this paper, a brief review on the classification of microgrids and how they work in two operating modes is presented. Based on the distribution system, microgrids are classified into alternating current, direct current and hybrid. Microgrids can work in two operating modes, connected to the network and islanded, each of which has unique goals and specific advantages. System stability, integrated power transfer and management of the balance between production and demand are the main challenges in the transition between two modes of microgrid operation. Based on the operation of the microgrid, different control strategies and protection systems are needed. Some control strategies are stated in each mode and a comparison between the two modes is presented. The microgrid system depends on many variables, and therefore their power management and stability are of particular importance. This study will be useful for researchers who work in the field of microgrid application, and it can be used in the design of controllers and protection system of microgrids.