Contents I. Introduction
Various studies, including the verification tests of dc microgrids, have been reported to enhance the reliability of the entire system [1]–[5]. A dc microgrid helps achieve efficient power transfer by reducing the number of power conversion stages between the ac and dc sides, because most grid-tied renewable energy systems deal with dc power on both input and output sides. Line impedances are usually very low in a dc microgrid owing to the shorter distances between the nodes such as the generators, batteries, and loads compared with a large-scale ac grid; thus, a large current flows through the lines even for a slight change in voltage. To suppress the excess current, a two-level converter needs a bulky output filter. To overcome these limitations in a microgrid, a converter with high speed and precise power flow control is required. However, with a large LC filter, power flow cannot change rapidly, even for a sudden change in the reference of the power flow and load conditions.
