Connecting External Sources SMA Solar Technology AG
150 SI2012_2224-TEN082311 Technical Description
13.2.8 Operation Together With Sunny Boys
Since electricity is fed into the grid through the relay of the Sunny Island, it must be prevented from
overloading. For this reason, reverse power monitoring is used which, if required, disconnects the
main power grid if the reverse power limit is exceeded or an excessive load is applied to the relay.
If the battery is fully charged, the frequency limits the power output of the AC feed-in generators
(Sunny Boys) in the stand-alone grid. If the grid is now reconnected, the frequency would be
lowered, if required, as the Sunny Island is synchronized with the grid. The AC feed-in generators
(Sunny Boys) would then feed additional energy into the system and possibly overload the batteries.
In order to prevent this, in this case the stand-alone grid frequency is temporarily increased
("231.04 AcSrcFrqDel" parameter), in line with the synchronization, until the AC feed-in generators
(Sunny Boys) are disconnected from the stand-alone grid as a result of the grid limits being
exceeded.
NOTICE!
If the current flowing through the relay exceeds the maximum permissible current, the grid
is disconnected (relay protection). The quantity of PV output installed in the stand-alone
grid must not exceed the maximum quantity allowed by the AC input (see section 20
"Technical Data" (Page 197)).
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