Siemens SINAMICS S120 System Manual page 36

Function modules
5.3 Description of the function modules
Prerequisite for the operating mode "Grid control" is that the DC link voltage is specified or
controlled by one of the connected power generating units (generator-inverter, battery,
photovoltaic array, etc. ).
Note
Automatic shutdown
The Active Line Module switches to this operating mode in the case of frequency faults
(120% of the set upper frequency threshold p0284 – or 80% of the lower frequency threshold
p0285) and shuts down to protect itself (overcurrent, overvoltage, overtemperature, etc.).
Smaller frequency and voltage deviations – as well as voltage dips or phase steps in the grid
– do not result in a shutdown as a result of the fault ride through function (FRT). The filter
monitoring p3667 must be activated in order to guarantee that for system-internal short-
circuits (e.g. in the Active Interface Module), the system is immediately shut down.
Depending on the requirements relating to the particular application, for example, the
parameterizable grid monitoring (p5540 and higher) can be used.
The shutdown limits for overcurrent (F30001, F6200 to A6205 = 128), overvoltage
(Vdc_max, F30002, F30003, F6200 to A6205 = 16), overtemperature, I2t are described in
the List Manual.
Functions
● Control of line voltage and line frequency (grid former)
● Stationary and dynamic load distribution to other energy producers in the network using
droop characteristics
● Provision of reactive current and short-circuit current for clearing network incidents
● An autonomous island grid can be established and maintained using the "Island grid
black start" function.
● An island grid can be connected to an external grid using the "Synchronize island grid to
an external grid" function. To achieve this, the voltage amplitude and frequency of the
island grid is modified in operation, and before closing the disconnector, adapted to that
of the external grid.
● Droop function to control the frequency and voltage of the network, including load
distribution
● Sequential control and current limitation control for mains voltage dips and short-circuits
● Modulation depth control to achieve the optimum modulation depth for minimum grid
harmonics
● DC component control ensures a line current that is free from DC components and thus
avoids saturation effects in the transformer
● Voltage control for compensating the voltage drop at transformer
● Damping elements and filters to stabilize an island grid
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System Manual, 04/2015, A5E03347436A
Grid infeed