Reactive Current Control; Harmonics Controller - Siemens SINAMICS S120 Function Manual

3.1.5

Reactive current control

Function description
A reactive current setpoint can be set to compensate the reactive current or to stabilize the line
voltage in infeed operation. The total setpoint is the sum of the fixed setpoint p3610 and the
dynamic setpoint via the connector input p3611.
● The direction of rotation of the line supply is compensated automatically with reactive
current control.
– A negative reactive current setpoint (r0076 < 0) causes an inductive reactive current
– A positive reactive current setpoint (r0076 > 0) generates a capacitive reactive current
● The closed-loop control limits the reactive current setpoint dynamically in such a way that
the sum of the active current setpoint and the reactive current setpoint does not exceed the
maximum device current.
● The reactive current demand of a line filter selected in the configuration wizard is
automatically supplied by the Active Infeed Module. This means that the display value of the
current reactive current setpoint in r0075 no longer corresponds with the parameterized
total reactive current setpoint.
● The reactive power setpoint of the Active Infeed Module with respect to the line supply can
be obtained by multiplying the parameterized total reactive current setpoint by 1.73 rated
line voltage.
3.1.6

Harmonics controller

Function description
Harmonics in the line voltage cause harmonics in the line currents. With the activation of the
harmonics controller, the ALM generates a pulse pattern that contains harmonic components
in addition to the fundamental component. Ideally, the Active Infeed now sets an equally large
harmonic voltage to the harmonic voltage on the line side, and does not consume any power
for this harmonic. Despite the harmonic component of the line voltage, the line current remains
almost sinusoidal and does not load the line supply with additional harmonic currents.
However, the specific compensation of voltage harmonics to improve the line supply quality is
not possible.
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
(overexcited operation, lower output voltage and or lagging current).
(overexcited operation, high output voltage and/or leading current).
Infeed
3.1 Active Infeed
39