'Institute of Electrical and Electronics Engineers (IEEE)'
Doi
Abstract
This paper presents a new proposed topology of a
solid-state transformer (SST) for application in hybrid power
grids (ac and dc), in which the possibility of operating with
various voltage levels (multilevel) in both sides is the main
characteristic. At the interface with the power grid (primary
side), the proposed SST consists of an ac-dc converter in Y
configuration that guarantees operation with five levels in each
phase-to-neutral voltage. To establish the hybrid power grid on
the secondary side, the SST is composed of a dc-ac converter in
Y configuration to establish an ac-grid, also operating with five
levels in each phase-to-neutral voltage, and by a dc-dc converter
to establish a dc-grid, which operates with three voltage levels.
The interface between the converters of the primary side and
the secondary side is guaranteed by an intermediary isolated
dc-dc converter. As fundamental requirements, the proposed
SST operates with balanced and sinusoidal currents on the
primary side, and with balanced and sinusoidal voltages on the
secondary side (ac-grid), as well as controlled voltages and
currents on the dc-grid. Throughout the paper, the proposed
topology for the SST is described in detail, with the operating
principle of each converter being presented. The obtained
results, both on steady-state and transient-state, for several
main operating conditions, prove the correct functioning of the
proposed SST, highlighting important features that
contextualize the operation of the proposed SST in smart grids.This work has been supported by FCT -Fundacao para a Ciencia e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project newERA4GRIDs PTDC/EEI-EEE/30283/2017, and by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT