An SST’s input output can interface with either
AC power systems.
This broad range capabilities makes SSTs key
tool for enabling future grids where efficient and
controllable power flow will required [42]. Here, the first power
electronics stage converts the medium-voltage
input (AC DC) into medium frequency AC
signal.4 Solid state transformers
Solid state transformers (SSTs), also known as
electronic power transformers power electronic
transformers, are voltage conversion devices
based power electronic. They allow
greater control and flexibility the primary
and secondary sides the voltage conversion
process than traditional passive low frequency
AC transformers. The general structure of
a SST shown Figure 4-4.
Figure 4-4 General structure SST
. The medium frequency transformer (MFT)
provides galvanic isolation and, some cases, a
high voltage conversion ratio from medium voltage
(MV) low voltage (LV). Many SST designs allow control
of power and voltage (and, for networks,
frequency, reactive power and power quality).
4.
Key: MFT indicates medium frequency (MF)
transformer, and represents AC
voltage, depending the design the SST. The second stage then
converts the medium-frequency, low-voltage
AC signal into the desired low-voltage output
(AC DC).35
MVDC technologies and operational considerations
Figure 4-3 Indicative circuit diagram modular multilevel converter (left), and submodule from
a modular multilevel converter (right)
DAB topologies are widely considered the
preferred choice for isolated MVDC converter
applications, and MMC for non-isolated MVDC
converter designs [41].2. Devices
