A bidirectional approach for segregated DC microgrids

The extension of a segregated DC microgrid with different voltage levels to a fully bidirectional grid is surveyed in this paper. The approach offers efficient implementation of small sources of regenerative energies and distributed energy storage systems as well as the possibility to even include electric vehicles as sources with high capacity. Furthermore, energy stored in any part of the grid, regardless of the voltage domain, is accessible. The use of local SELV sub-units diminishes safety measures otherwise necessary in the LVDC domain. The concept with its assets and drawbacks is presented as well as hardware, requirements, and challenges concerning the realization. An analytical model to estimate the benefit is introduced and sample data for an existing microgrid are showcased.