SMA SC 500HE-20 User Manual
Page 45
SMA Solar Technology AG
6 Setpoint for Active Power and Reactive Power
Operating Manual
SCxxxHE-20-BE-BEN111210
45
If the power frequency exceeds a user-defined limit "P-HzStr" as shown in point A, the Sunny Central
will save the current feed-in power P
cur
. The reduced feed-in power is calculated based on this saved
value. The reduction of the feed-in power is defined through the "P-WGra" parameter. This parameter
indicates by which percentage of the saved power P
cur
output will be reduced per Hz if the power
frequency continues to rise.
If the power frequency decreases again as shown in point B, the last reached feed-in power will
remain valid. Only if the power falls below the user-defined limit "P-HzStop" as shown in point C, the
fed-in power may be increased again. The saved value "P
cur
" will be rendered invalid.
If the power frequency exceed the grid limit, the Sunny Central will shut down and switch over to the
"Grid monitoring" operating state. The Sunny Central will remain in the "Grid monitoring" operating
state until all feed-in conditions are fulfilled again.
Calculating the power limit
Formula: P
lim
= P
cur
– ( (f
grid
– P-HzStr) * P-WGra * P
cur
)
6.1.10 Active Power Limitation Procedure Depending on Power
Frequency and Associated Parameter Setting
1. Make sure the inverter is in the "Stop" operating state.
2. Access the SC-COM interface.
3. Enter your password in the appropriate field on the homepage and press [Login].
4. On the SC-COM interface, set the "WCtlHzMod" parameter to On (see section 5.2 "Changing
5. Change used parameters.
P
lim
Power limit
P
cur
Current power
f
grid
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 Sunny Central with 500 kW is feeding 350 kW (P
cur
) into the power distribution grid. The
frequency will reach up to 51.2 Hz.
The difference between the current power frequency and P-HzStr (51.2 Hz ‒ 50.2 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 – ( (51.2 Hz – 50.2 Hz) * 40%/Hz * 350 kW)