Application of island microgrid based on hybrid batteries storage

Abstract

This paper describes a MW-level island microgrid system which is constructed on 4226 meters high plateau in the western of China. The microgrid system is composed of 7MWp PV modules, 5MWh lithium batteries and 20MWh lead-acid batteries, which are integrated with power electronic interface without stable generation source. A master-slave control structure is adopted in the system. Batteries Energy Storage Systems (BESSs) play as different function roles, and the cooperative control method of BESSs is presented to support the power balance during system operation. Master Battery System (MBS) is equipped with lithium batteries which handles the frequency and voltage as a master control unit. Slave Battery System (SBS) is equipped with large capacity lead-acid batteries which are used as energy reserve devices and operated as slave units. Regulation Battery System (RBS) is operated as slave unit for short-term energy scheduling, which is also used as a spare master unit for black-start and system maintenance. According to the cooperative data, the coordinated control and energy management of island microgrid system are able to guarantee it operate stably and reliably under different dynamic conditions. Meanwhile, operation conditions of batteries are greatly improved in this application.