Technical Description
10
Functionality of the Inverter
REFUsol 50K-3T
982081 | 03 | 2021-03
3
Technical Description
3.1 Functionality of the Inverter
The
REFUsol 50K-3T
is a multi-string inverter with
three MPP trackers that converts the DC voltage gen
-
erated by the photovoltaic modules into AC voltage and
can feed the power into the low or medium voltage grid.
Fig. 2: Functional principle of a grid-connected PV system
A DC switch is integrated at the DC input of the
inverter; this disconnects the inverter from the PV
modules. The PV inverter has three independent MPP
trackers on the input board. These can be operated in
parallel mode or in independent mode.
The input board provides extensive functions,
including insulation monitoring, DC voltage and cur
-
rent monitoring and reverse polarity protection. EMC
filtering is also performed on this board to suppress
unwanted noise levels at the DC input.
The DC-DC boost converter controls the level of the
DC voltage, which is fed to the inverter board, where
the DC current is converted into AC current. On the out
-
put board, EMC filtering of the AC current, fault current
1
Photovoltaik (PV) modules
2
Solar string combiner box
3
Photovoltaic inverter
4
AC protection (fuse switch disconnector or circuit breaker)
5
Grid protection
6
Isolation transformer is required for medium-voltage grid
7
Low or medium-voltage AC grid
