1. XJ Electric Co. Ltd., Xuchang 461000, China;2. Xi'an XJ Power Electronics Technology Corporation, Xi'an 710075, China;3. Xuji Group Corporation, Xuchang 461000, China

In the energy storage system without communication interconnection line, it is difficult to maintain power balance and voltage stability of DC bus without the increase of cost and complexity. To solve this problem, a coordinated control strategy for DC bus is proposed. The DC/AC converter is in constant DC voltage control mode or constant AC voltage control mode. An improved two-stage DC voltage deviation control method including battery charging/discharging control is used in two DC/DC converters. The typical operating modes are analyzed to show how these converters work together in the system. A microgrid experimental platform is set up to verify the proposed control strategy. The effectiveness and practicability of control strategy are verified by the experimental results.