User's Manual

SINVERT PVS in power plants 15
The inverters integrated in the inverter stations operate with a rotating master according to the master-slave principle.
The diagram shows in simplified form that the master moves to the next inverter each day (see left column). In actual fact, the inverter with the fewest
operating hours is started as the master on the next day.
Master-slave system with SINVERT PVS
The SINVERT PVS inverters integrated in the inverter stations
operate with a "rotating master" according to the master-slave
principle. This is a master-slave system comprising between
two and four interconnected inverter subunits. It employs an
ingenious process to connect or disconnect inverter subunits,
depending on the level of solar irradiation (determined
according to the sun's path, cloud conditions, etc.). The mas-
ter is started up first and operates even when irradiation levels
are low. As irradiation levels increase, the next inverter
subunit is switched in as a slave when a set switching thresh-
old is exceeded. Depending on the configuration, up to three
slaves can be switched in. As irradiation levels drop again, the
subunits are disconnected in stages. One advantage of the
master-slave principle is that the efficiency factor is higher
when irradiation levels (which determine the PV generator
output) are low than it would be if only a single inverter were
used.
In master-slave systems, the "rotating master" function always
starts the inverter subunit with the fewest operating hours as
the master. In this way, the total operating hours are evenly
distributed among all the subunits.
■ Individual components of the inverter stations
– SINVERT PVS inverters according to IEC and their
components (for further information see Catalog
RE10 "Inverters and Components for Photovoltaic
Installations")
– AC distribution for voltage supply, control and
monitoring of the components.
– Medium-voltage transformer
– Medium-voltage switchgear
For technical data on the fully configured inverter stations,
the AC distribution, the medium-voltage transformer and the
medium-voltage switchgear, please contact your local sales
partner:
www.siemens.com/sinvert/partner
Medium-voltage transformer
The medium-voltage transformer transforms the low voltage
supplied by the SINVERT PVS photovoltaic inverter into a
defined medium voltage of 20 kV, for example, for feeding
into the grid.
Several medium-voltage transformer brands are available,
e.g. the loss-optimized GEAFOL medium-voltage transformer
(cast-resin two-tier transformer), which has been specially
designed for photovoltaic applications.
Detailed information about GEAFOL medium-voltage trans-
formers can be found in the Catalog TV 1 "GEAFOL cast-resin
transformers 100 to 16 000 kVA".
Medium-voltage switchgear
The medium-voltage switchgear is available as an option.
It distributes energy and feeds power into the medium-voltage
network.
Detailed information about medium-voltage switchgear can
be found in the Catalog HA 40.2 "Switchgear Type 8DJH for
Secondary Distribution Systems up to 24 kV, Gas-Insulated".
RE10_00034
Intensity of solar irradiation
1st day
2nd day
3rd day
4th day
morning noon evening night
3_PVS in Power-Plant-Anlagen.fm Seite 15 Freitag, 25. Mai 2012 2:29 14
© Siemens AG 2012