SMA SC 500HE-US - Manual (Page 35)

SMA America, LLC 7 Active Power Limitation
Operating Manual SC500HEUS-eng-BE-BUS120320 35
7 Active Power Limitation
The Sunny Central can limit its active power if requested by the grid operator. The limitation of the
active power can be performed both dependent on the power frequency and independent of the grid
frequency. The frequency-dependent active power limitation is regulated in accordance with the
specifications of IEEE 1547 and cannot be changed. This section describes the function and
parameterization of both types of active power limitation.
7.1 Power Frequency-Dependent Active Power Limitation
During active power limitation dependent on the power frequency, the Sunny Central constantly
checks the connected power frequency.
Figure 11: Behavior of the Sunny Central when exceeding the "P-HzStr" frequency limit
If the power frequency exceeds a limiting value defined in the parameter "P-HzStr", shown under point
A, the Sunny Central will save the current feed-in capacity P
mom
. The reduced feed-in capacity is
calculated based on this saved value. The reduction of the feed-in capacity is defined by the
parameter "P-WGra". This parameter indicates the percentage of the saved power P
mom
by which the
power per Hz will be reduced if the power frequency continues to rise.
If the power frequency decreases again as shown in point B, the last reached feed-in capacity will
remain valid. Only if the power falls below the limiting value defined in the parameter "P-HzStop",
shown here in point C, can the fed-in power be increased again. The saved value P
mom
will be
rendered invalid.
If the power frequency exceeds the grid limit, the Sunny Central will shut down and switch over to the
operating state "Grid monitoring". The Sunny Central will remain in the "Grid monitoring" operating
state until all feed-in conditions are fulfilled again.