Abstract

Microgrids can be understood as a complete electrical power system in all characteristics which are inherent to them but on a tiny scale. Although small scaled, they are endowed with high operational and constitutive sophistication enabling them to operate independently, sometimes connected to the distribution system and other times, appropriately, as an isolated system. The paradigm of central control does not exist anymore in this operational philosophy. Thanks to the high quantity and quality of information received from the bulk system summed to the decentralized operation, microgrids can locally provide a higher level of reliability than that provided by the whole system. This chapter gives an overview of electrical power systems evolution stating its current situation with regard to its own function, economic aspects, and environment relationship.