Siemens sinamics dcp Operating Instructions Manual page 266

Operation
8.16 Technological functions
Current setpoint:
This value must be specified in the SINAMICS DCP as the current setpoint (p55050 =
r54021). The current setpoint is generated by ramp-function generator, which in each cycle
receives a higher pulse or lower pulse. The ramp-up/ramp-down time of the ramp-function
generator is formed from the set value for the current stage (parameter p54006).
If the power in the current cycle is higher than it was in the previous cycle, it receives the
same pulse as in the previous cycle, otherwise it receives the opposite pulse.
This means that if the power increases because the current is increased, the current is
increased yet again. However, if the power drops when the current is increased, the current
is reduced.
The ramp-function generator is stopped when it reaches a current limit that can be defined
via BICO (parameter p54013).
The current setpoint can be output as a positive or negative value, depending the side on
which the solar panel is connected (parameter p54009). In standard configurations, the solar
panel is connected on side 2 and negative current flows.
Setting value and setting signal:
● Pulse enable: As long as no pulse enable is pending (r899.11 = 0), the MPP Tracker is
set to the current setpoint in manual operation.
● Manual/Automatic operation:
Automatic operation:
The MPP Tracker is effective. Its output is connected on as the current setpoint.
Manual operation:
The MPP Tracker is not effective. The current setpoint is specified via BICO from a higher-
level controller (parameter p54000). The ramp-function generator of the MPP Tracker is set
to the present current setpoint.
Switchover between manual and automatic operation is performed by a binector (parameter
p54001).
● Undervoltage: The voltage of the solar panel is monitored to detect whether it falls below
the parameterizable limit. If this happens, the current setpoint is immediately reduced by
a specific factor (parameter P54007). This function allows the MPP to respond quickly if
the solar panel is suddenly shaded by cloud.
Plotting the PV array curve
The characteristic curve of a PV array can also exhibit local maxima. To ensure that the
search does not become permanently stuck at a local maximum, the entire curve (as far as
possible) is searched at regular intervals (p54035) and the global maximum power is
calculated. The search is limited to a settable range (p54037) around the global maximum.
266
Operating Instructions, 05/2016, A5E34382853K
SINAMICS DCP