Siemens 600 Master-slavesystem with SINVERT PVS, Individual components of the inverter stations

© Siemens AG 2012

Intensity of solar irradiation

morning noon evening night

1st day

2nd day

3rd day

4th day

RE10_00034

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".

SINVERT PVS in power plants 15