10.1.3
Reactive power functions
The following functions for controlling the reactive power are implemented in the devices listed above:
cos φ constant
Q constant
cos φ /(p/pn)
Q(U) 10 nodes
Reactive power is prioritised in each method. The maximum possible active power that can be fed in is reduced in line
with the P-Q operating range when a specific reactive power level is specified.
cos φ constant
When there is a cos φ constant, the specified shift factor cos φ is set permanently by the inverter. In doing so, the react-
ive power level is set in line with Q=P*tan φ dependent on power output such that the specified shift factor cos φ is calcu-
lated on an ongoing basis. If the specification is changed, the new value is adopted by way of a filter in a muted manner.
The settling time is 1s with the transient response of a first-order filter (PT-1) with a time constant of Tau = 200 ms. The
specified shift factor can be configured on the display or by way of communication via the RS485 protocol of KACO and
MODBUS/SunSpec.
If the applicable grid connection guidelines call for cos φ to be adjusted to the target value with a defined gradient or a
defined settling time that is shorter than the configured Tau = 200 ms, then this gradient or settling time must be imple-
mented on the plant controller.
Q constant
When there is a Q constant, the specified reactive power value is set permanently by the inverter. If the specification is
changed, the new value is adopted by way of a filter in a muted manner. The settling time is 1s with the transient re-
sponse of a first-order filter (PT-1) with a time constant of Tau = 200 ms. The specified reactive power can be configured
on the display or by way of communication via the RS485 protocol of KACO and MODBUS/SunSpec.
If the applicable grid connection guidelines call for the reactive power to be adjusted to the target value with a defined
gradient or a defined settling time that is shorter than the configured Tau = 200 ms, then this gradient or settling time
must be implemented on the plant controller.
cos φ /(p/pn)
When it comes to cos φ (p/pn), the cos φ and, deduced from this, the reactive power target value are calculated continu-
ously as a function of the current power level. This function ensures that grid support is provided by the reactive power
when a significant voltage boost is anticipated due to a high feed level. In this case, a characteristic curve is specified
which can be used to configure up to 10 nodes, value pairs for active power and cos φ. The active power is entered as a %
in relation to the nominal power. Other parameters allow you to limit functionality and to limit activation to certain
voltage ranges.
Fig. 30:
cos φ / (P/Pn) standard characteristic curve with 3 nodes
KACO blueplanet gridsave 50.0TL3-S
Page 52
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