SMA Solar Technology AG
3 Product Description
User Manual
SCCP-JP-BA-A4-en-12
31
3.8.8 Q at Night
With the order option "Q at Night", the Sunny Central can provide reactive power in order to stabilize the utility grid
during non-feed-in operation, e.g. at night. This function is independent of normal feed-in operation.
Only limited dynamic grid support is available in the operating state "Q at Night".
Figure 12: Principle overview of the operating states of the Sunny Central in "Q at Night" operation
If the AC power generated by the inverter falls below 5 kW, the inverter switches from feed-in operation to "Q at Night"
operation. The inverter feeds in reactive power in accordance with the parameters set. Since this status can also occur
during the day, the DC switchgear remains closed at first in order to avoid unnecessary switching cycles of the DC
switchgear. If the inverter is in "Q at Night" operation for one hour or the DC current falls below 60 A, the DC switchgear
opens. The inverter continues to feed in reactive power.
If reactive power feed-in is interrupted after a grid fault and the AC contactor is opened while the DC switchgear is open,
the DC circuit will first be pre-charged. This reduces the stress on the electronic components. This process takes a maximum
of one minute. Once the DC circuit is sufficiently pre-charged, the AC contactor is closed and the inverter monitors the
grid limits. If all of the feed-in requirements are met, the inverter will revert to reactive power feed-in within one minute.
While the inverter is feeding in reactive power, the inverter monitors whether the conditions for active power feed-in are
met. Once the feed-in requirements are met, the inverter closes the DC switchgear and switches to feed-in operation.
To protect the PV array, the amount of reverse current is set by default to − 60 A in the parameter
QoDInvCurPv.
This value must be adjusted according to the maximum permissible reverse current of the PV array.
