SMA SC 500CP-US-10 600V - Manual (Page 53)

SMA America, LLC 7 Active Power Limitation
Operating Manual SCCP-US-BE-US_en-52 53
If the power frequency exceeds the grid limit, the inverter will shut down and switch over to the "Grid monitoring"
operating state. The inverter will remain in the "Grid monitoring" operating state until all feed-in conditions are fulfilled
again.
Calculating the active power limit:
Formula: P
lim
= P
cur
– ( (f
power
– P-HzStr) * P-WGra * P
cur
)
7.2 Active Power Limitation Independent of the Frequency
7.2.1 Selecting the Procedure with the Parameter P-WMod
You can set the active power limitation via the parameter P-WMod (see Section 6.2 "Changing Parameters", page 51).
Use the parameter to configure how the specifications of the grid operator are to be received and implemented. The
default setting for this parameter is Off.
There are five different procedures for power frequency-independent active power limitation:
Active Power Limitation Procedure and Setting Associated Parameters
1. Ensure that the inverter is in the "Stop" operating state.
2. Log in to the user interface.
3. Enter the password in the appropriate field on the homepage and confirm with [Login].
4. Change the parameter P-WMod in the user interface. Select the desired procedure from the list (see Section 6.2
"Changing Parameters", page 51).
5. Change parameters belonging to the selected procedure.
P
lim
Power limit
P
cur
Current power
f
power
Power frequency
P-HzStr Selected frequency limit at which the feed-in power will be reduced
P-WGra Gradient for reducing active power
Example:
A inverter with 500 kW is feeding 350 kW (P
cur
) into the utility grid. The frequency will reach up to 61.2 Hz.
The difference between the current power frequency and P-HzStr (61.2 Hz - 60.2 Hz) multiplied by the gradient
P-WGra (40%/Hz) results in an active power reduction of 40% in the last available power P
cur
(350 kW). This results
in a power limitation of 140 kW and a maximum active power of 210 kW.
Calculation:
210 kW = 350 kW – ( (61.2 Hz – 60.2 Hz) * 40 %/Hz * 350 kW )
Parameter blocking
The parameter P-WMod may only be changed in the operating state "Stop". The entry will not be accepted in other
operating states.
Procedure Description
Off The active power is limited to the device nominal power Pmax.
WCtlCom The active power limitation is received by the SC-COM via Modbus and then transmitted to the
inverter.
WCnst The active power limitation is entered as an absolute value via the parameter P-W.
WCnstNom The active power limitation is entered as a percentage value via the parameter P-WNom.
WCnstNomAnIn The active power limitation is set at the input terminals using an analog signal for the setpoint.