Grid Reconnection; Grid Operation - SMA SUNNY ISLAND 4548-US Operating Manual

14 Connecting External Sources

14.2.5 Grid Reconnection

In stand-alone mode, the Sunny Island constantly checks whether the grid has been reconnected (see
above). The following conditions have to be fulfilled to guarantee that the Sunny Island synchronizes
with the utility grid and connects to the utility grid:
• The frequency of the utility grid must be between the values of the parameters
"232.05 GdFrqMin" and "232.06 GdFrqMax" for the time defined in the parameter
"232.07 GdVldTm".
• The voltage of the utility grid must be between the values of the parameter "232.01 GdVtgMin"
and 5 V below the parameter "232.02 GdVtgMax" for the time defined in parameter
"232.07 GdVldTm".

14.2.6 Grid Operation

During grid operation, the stand-alone grid and the utility grid are connected. The Sunny Island is
connected along with the stand-alone grid to the utility grid. In this case, the voltage and frequency
in both grids are identical.
Disturbances of the utility grid
All disturbances of the utility grid affect the stand-alone grid during grid operation.
In grid operation, the grid monitoring checks whether the permissible limits for voltage and frequency
(see grid reconnection) are maintained or whether the grid fails to assume supplying the stand-alone
grid. For this, the utility grid is disconnected (battery-backup operation).
The battery is generally charged or its charge is maintained on the utility grid.
Charge Mode
Charge mode on the utility grid is indicated by energy flowing to the battery. The battery is charged
until the respective charge process (Boost, Full, Equalize) has been completed and the system
changes to float charge (Float) (see Section 13.5 "Charge Control", page 111).
Utility grid as generator: charging the Sunny Island via the utility grid to avoid
deep discharge
Manual grid start deactivates settings for automatic grid start
Via the parameter "560.01 GdManStr", you can define whether the utility grid is to be
connected or not:
• "Stop": the utility grid will never be connected.
• "Start": the utility grid is always connected.
• "Auto": the utility grid connects automatically and protects the battery from deep
discharge.
The following section describes how to perform the settings for an automatic grid start.
You can configure the Sunny Island in such a way that it charges its battery automatically via the utility
grid as soon as the state of charge is low. To activate this function, set the parameter
"232.41 GdSocEna" to "Enable" and the parameter "560.01 GdManStr" to "Auto."
132 SI4548-6048-US-BE-en-21
SMA Solar Technology America LLC
Operating Manual