SMA SC 500CP-US-10 600V - Manual (Page 40)

3 Product Description SMA America, LLC
40 SCCP-US-BE-US_en-52 Operating Manual
3.7.7 Q at Night
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With the configuration option "Q at Night", the inverter 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 16: General overview of the operating states of the inverter in the operating state "Q at Night"
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 of the DC switchgear.
If the inverter has been in the "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 is initially pre-charged. This reduces the stress on the electronic components. This procedure requires 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 starts reactive power feed-in again within
one minute.
While the inverter is feeding in reactive power, the inverter monitors at the same time whether the conditions for active
power feed-in have been met. If the feed-in requirements are met, the inverter closes the DC switchgear and switches to
feed-in operation.
The amount of reverse current is set to -60 A by default in the parameter QoDInvCurPv to protect the PV array.
This value should be adjusted according to the maximum permissible reverse current of the PV array.
Q at Night is not UL listed
The order option "Q at Night" is not part of the UL 1741 listing, but may be used without loss of inverter certification
if permitted by the Authority Having Jurisdiction (AHJ).