**Yingshu Liu \*, Yue Fang and Jun Li**

School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China; fangyue@tju.edu.cn (Y.F.); lijunxaut@163.com (J.L.)

**\*** Correspondence: liu\_ysh@tju.edu.cn; Tel.: +86-159-2209-7591

Received: 14 July 2017; Accepted: 28 August 2017; Published: 30 August 2017

**Abstract:** A novel and flexible interconnecting framework for microgrids and corresponding energy management strategies are presented, in response to the situation of increasing renewable-energy penetration and the need to alleviate dependency on energy storage equipment. The key idea is to establish complementary energy exchange between adjacent microgrids through a multiport electrical energy router, according to the consideration that adjacent microgrids may differ substantially in terms of their patterns of energy production and consumption, which can be utilized to compensate for each other's instant energy deficit. Based on multiport bidirectional voltage source converters (VSCs) and a shared direct current (DC) power line, the energy router serves as an energy hub, and enables flexible energy flow among the adjacent microgrids and the main grid. The analytical model is established for the whole system, including the energy router, the interconnected microgrids and the main grid. Various operational modes of the interconnected microgrids, facilitated by the energy router, are analyzed, and the corresponding control strategies are developed. Simulations are carried out on the Matlab/Simulink platform, and the results have demonstrated the validity and reliability of the idea for microgrid interconnection as well as the corresponding control strategies for flexible energy flow.

**Keywords:** interconnection of microgrids; energy storage equipment; energy router; voltage source converter
