Overview of microgrid

The gradual decrement of fossil fuels, low energy efficiency and environmental problems met all over the world has led to several power system researches. These problems have promoted researches on alternative energy sources such as wind energy, solar photovoltaic, fuel cells, combined heat and power (CHP) systems, and micro turbines on the contrary of conventional resources. Moreover, the integration of renewable energy sources (RESs) to existing power grid is taken into account as a reliable and robust solution to aging generation, transmission and distribution systems. The innovative researches have brought a new concept as on-site generation or distributed generation at load sites. The utilized resources in this generation concept are later called as distributed energy resources (DERs) implying for a wide variety of power sources, and the generation type is named as distributed generation (DG). This chapter presents an introduction to microgrid concept by including distributed generation and active distribution networks, several DERs such as synchronous generator based and RES based resources, microgrid architectures, operation principles of microgrid, microgrid modeling studies, control and protection issues of microgrid