SMA SC 500CP-10-JP - Manual (Page 55)

SMA Solar Technology AG 8 Power Control
User Manual SCCP-JP-BA-A4-en-12 55
8.2.1.3 Reactive Power Control with Setpoint Command via Modbus Protocol:
VArCtlCom Mode
The reactive power setpoint is received by the Sunny Central via the Power Reducer Box or the Power Plant Controller.
The setpoint is transmitted as a percentage and converted to kVAr in the device.
If the Sunny Central has not received any signal for the last five minutes, the error message Q-VArModFailStt will be
displayed (see Section 8.2.2, page 63).
8.2.1.4 Reactive Power Control with Setpoint Command via Modbus Protocol: PFCtlCom
Mode
The reactive power setpoint is received by the Sunny Central via the Power Reducer Box or the Power Plant Controller.
The setpoint is transmitted as a displacement power factor cos φ.
If the Sunny Central has not received any signal for the last five minutes, an error message will be displayed in the
instantaneous value Q-VArModFailStt (see Section 8.2.2, page 63).
8.2.1.5 Reactive Power Control with Absolute Value: VArCnst Mode
The Q-VAr parameter is used to set the reactive power setpoint. The permitted range of the parameter Q-VAr is between
‒Qmax and +Qmax.
8.2.1.6 Reactive Power Control as a Percentage of the Nominal Power: VArCnstNom
Mode
The parameter Q-VArNom is used to set the reactive power setpoint in %. The parameter Q-VArNom refers to Pmax.
If the calculated amount of reactive power exceeds the predefined value of Qmax, the power will be limited to Qmax.
If the calculated amount of reactive power falls below the predefined value of ‒Qmax, the power will be limited to
‒Qmax.
8.2.1.7 Reactive Power Setpoint via Standard Signal: VArCnstNomAnIn Mode
The reactive power setpoint is set via an analog signal at the input terminals for setpoint specification (see Sunny Central
installation manual). 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 (see Section 8.2.2, page 63).
The analog value is converted to a setpoint for power limitation. Here, the Qmax parameter forms the end point of the
linear characteristic curve.
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 − Pmax The maximum amount of negatively excited reactive power is fed in.
4 mA − Pmax 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 +Pmax End point of the characteristic curve
The maximum amount of positively excited reactive power is fed in.