This paper investigates a specific type of converter-based general interface, which can be used for AC microgrids integrating to the active distribution network. The interface, a Back-to-Back (BtB) converter, is used to connect the AC sides of the distribution network and the microgrid. The common DC link of the BtB converter is connected to one terminal of a bidirectional DC-DC converter whilethe other terminal of the DC-DC converter is connected with an energy storage system. By adopting proposed coordinated control within the interface, the distribution network and the microgrid can be decoupled in terms of the AC voltage and current. Furthermore, this interface can provide enhanced voltage stability and high power quality in the case of severe disturbances on the AC side. Hence, the microgrid can be integrated into the distribution network in a safe and flexible way. A testing system is built using RSCAD and the structure and control strategy proposed in this paper are verified through the Real Time Digital Simulator (RTDS).