Siemens SINAMICS S120 System Manual page 57

the generator inductances in the island grid. The downstream voltage controller ensures a
steady-state accuracy of the voltage amplitude at the connection terminals, and therefore
compensates the impedance of the inverter generating system.
Figure 6-3 Grid droop control
Droop characteristics f
power balance between the generating units in a microgrid, and result in power-dependent
and remaining deviations of the f and U setpoints. The necessary subsequent control of f
and U
shown here. This is the task of a higher-level power management system.
In grid forming operation, the currents are defined by the load. Currents with harmonics –
e.g. as a result of non-linear loads – generate the corresponding voltage drops between the
inverter and line connection point; these can be reduced using harmonic output voltage
Grid infeed
System Manual, 04/2015, A5E03347436A
(t) and U
droop
to return to the rated f-U values after load changes, is not part of the control scheme
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Detailed descriptions of the function modules
6.2 Controls for grid droop operation
(t) represent proportional controllers for controlling the
droop
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