The state-of-the-art and typical characteristics of the energy interconnection system(EIS)and microgrid are reviewed from the interpenetration and interrelation perspective of the two systems. Six “cell” functions of microgrids to facilitate the future EIS

namely

improving power quality

enhancing reliability and resilience

coordinating energy dispatch among different areas

achieving load active control and bidirectional information flow

and promoting resources utilization efficiency

are further analyzed from the six features of microgrid including deployment localization

source/load diversification

structural diversity

operational flexibility

controllability

and interactivity. In addition

several typical microgrid interconnection types are presented. Finally

key technologies and equipment to promote EIS development in the future are presented and predicted.