Country-
spec. Set-
tings
Men
u
level
Display/
Setting
Action in this menu/meaning
Over-excited | un-
der-excited
Reactive power mode Under-excited relates to inductive load, over-ex-
cited relates to capacitive load.
10.2
Regulating active power
Methods for regulating the active power of generation plants may be necessary for local management of load
flows, for voltage stability in the distribution network and for ensuring the stability of the interconnected grid.
The communication functions
P limit
and
P set (not PV!)
are available for managing load flows in a
plant. If necessary, this can be used to reduce the feed of the inverter.
If it is not possible to compensate adequately for voltage excesses in the upstream distribution network by in-
take on reactive power, it may be necessary to curtail the active power. In this case, P(U) control is available for
making optimum use of the capacity of the upstream grid.
Generation plants must assist with frequency stability in the grid. If the grid frequency leaves the normal toler-
ance range (e.g. ±200 mHz), then the grid will be in a critical state. In the event of overfrequency, there is a
generation surplus, in the event of underfrequency, there is a generation deficit. In the case of overfrequency
and underfrequency, photovoltaic systems and power storage systems must reduce their effective feed-in
power in relation to the increase in frequency. The P(f) function is available for this purpose.
The availability or the adaptability of the functions may be limited depending on the country setting selected.
This is particularly true if the applicable grid connection guideline makes this restriction compulsory.
Dynamics / accuracy
In all of the control methods described below the specified target value at the inverter’s connection terminals
is adjusted using a stationary deviation of the reactive power of maximum 2%
N
SN.
The transient response of the control methods is determined by a PT-1 filter. In this case, the settling time cor-
responds to 5 Tau, or in other words, achieving approx. 99% of the final value for a PT-1 filter. Subject to the
control method selected, there are also other parameters that determine dynamic behaviour.
Methods for active power regulation
Methods for regulating the active power of feed-in inverters may be necessary for local management of load
flows, for voltage stability in the distribution network and for ensuring the stability of the interconnected grid.
The device makes use of the following functions in order to regulate the active power. These are described in
the following section:
– P target value (MPPT(communication)) [See section 10.2.1
– P limit (communication) [See section 10.2.2
– P(U) (characteristic curve) [See section 10.2.3
– P(f) (characteristic curve) [See section 10.2.4
10.2.1 P target value
The function “P target value” is integrated into the MPP tracking of the inverter on all PV inverters. The P target
value is continuously re-calculated on the basis of the MPP tracking algorithm.
10.2.2 P limit
The function “P limit” is available for limiting the maximum feed-in power. If necessary, this can be used to re-
duce the maximum possible feed of an inverter, e.g. for managing bottlenecks for the operator of the distribu-
tion grid.
P limit is only available via the MODBUS/SunSpec inverter model 123
Immediate Inverter Controls
and via RS485 communication. You can find detailed information on the communication protocol at
in the “Software” subsection of the “Downloads” section.
10 | Specifications
Manual
KACO blueplanet 110 TL3 KACO blueplanet 125 TL3
Page 82
EN-US
