SMA SC 500CP XT - Manual (Page 104)

In addition, the parameter Q-VLockInW can be used to define a voltage at which reactive power control will be
activated after the time specified in parameter Q-VLockInTm has elapsed. If the voltage exceeds the threshold
defined in parameter Q-VLockOutW, the reactive power control will be deactivated once the time specified in
parameter Q-VLockOutTm has elapsed.
10.3.4 Q at Night
10.3.4.1 No Q at Night: Off Mode
The reactive power setpoint is limited to 0 kVAr. This setpoint cannot be controlled.
10.3.4.2 Q at Night with Operation Command via Modbus Protocol: VArCtlCom Mode
The reactive power setpoint is received by the communication unit and transmitted to the inverter. The setpoint is
transmitted as a percentage value and converted to kVAr in the device. If the inverter has not received any signal for
five minutes, the error message Q-VArModFailStt will be displayed.
10.3.4.3 Q at Night with Absolute Value: VArCnst Mode
The reactive power setpoint is set via the parameter QoDQ-VAr. The parameter QoDQ-VAr is permitted to be within
the range from ‒QoDQmax to +QoDQmax.
10.3.4.4 Q at Night as a Percentage of the Nominal Power: VArCnstNom Mode
The parameter QoDQ-VArNom is used to set the reactive power setpoint in %. The parameter QoDQ-VArNom
refers to Pmax. If the calculated amount of reactive power exceeds the predefined value of QoDQmax, it will be
limited to QoDQmax. If the calculated amount of reactive power falls below the predefined value of ‒QoDQmax, it
will be limited to ‒QoDQmax.
10.3.4.5 Q at Night via Standard Signal: VArCnstNomAnIn Mode
The reactive power setpoint is set at the input terminals for the setpoints via an analog signal. This is usually
implemented by a ripple control signal. The analog value is converted into a reactive power setpoint. The electrical
current strength of the connected signal determines the setpoint. The analog measured values must be between
4 mA and 19 mA. If the analog signal is less than 2 mA, an error message will be displayed in the instantaneous value
Q‑VArModFailStt.
Signal Power limit Description
< 2 mA Last valid mean value or 0 kVAr after
restart Signal is in the invalid range.
2 mA to 4 mA −QoDQmax / underexcited The maximum amount of negatively excited reactive
power is fed in.
4 mA −QoDQmax / underexcited Start point of the characteristic curve
The maximum amount of negatively excited reactive
power is fed in.
11.5 mA 0 kVAr Zero-crossing of the characteristic curve
No reactive power is fed in.
> 19 mA +QoDQmax / overexcited End point of the characteristic curve
The maximum amount of positively excited reactive
power is fed in.
10 Function Description SMA Solar Technology AG
User Manual SCCPXT-BA-E4-en-54 104