1. An Introduction to Microgrids, Concepts, Definition, and Classifications

Microgrids are self-sufficient energy ecosystems designed to tackle the energy challenges of the 21st century. A microgrid is a controllable local energy grid that serves a discrete geographic footprint such as a college campus, hospital complex, business center, or neighborhood. It connects to the grid at a point of common coupling that adopting voltage with the main grid in normal and can break off automatically or manually and works as an island using its local energy generation units in times of crisis. The microgrid concept assumes a cluster of loads and combination of distributed energy resources units such as solar panels, wind turbines, combined heat and power, energy storage systems such as batteries and also electric vehicle charging stations. Microgrids contribute to modify flexibility, reliability, and resiliency, accessibility of green and safe energy with ability to participate in demand response, cost optimization and grid-balancing programs. Microgrids can be categorized via different aspects ranging from the structure such as DC, AC, or hybrid to control scheme such as centralized, decentralized or distributed. This chapter reviews briefly the microgrid concept, its working definitions and classifications.