Abstract
A modular microgrid unit (MMGU) is a packaged microgrid that can work autonomously but is also capable of connecting to other MMGUs to form an expandable microgrid. It is flexible and can be implemented with different resources, such as hydropower or wind. An MMGU's power electronic interface accompanied with battery storage unit provides a high level of stability, which is critical in microgrids. A key factor when implementing an MMGU is to determine appropriate MMGU component ratings to match physical characteristics of available resources. This paper discusses the application of an MMGU in a pumped-storage unit. The main components of MMGU are introduced and equations are presented to find rating of these components. Then, typical MMGU component ratings for a 250-kW system are calculated and the feasibility of the design is assessed.