Parameter For Power Ramp; Advanced Islanding Detection - Kaco blueplanet 29.0TL3 Serie Manual

Manual
The soft start up is implemented by an absolute power limitation that increases with a continuous gra-
dient up to the maximum power. The actual power of the inverter may vary freely below this limit due
to a possible fluctuation in the available power or the target value, but at no time increases above the
absolute power limit.

10.4.2.1 Parameter for power ramp

Power ramp
1 2 3 4 4
Gradient
1 – 600 [% / min]
After every connect
After first connect
After grid error

10.5 Advanced islanding detection

Due to decentralized generation, there is the possibility that a deactivated part of the grid will remain li-
ve in an unintended island due to the balance of load and generation in this part of the grid. The detec-
tion of unintended island formation is an important function of decentralized generating units and is re-
lated to the prevention of damage to equipment as well as safety of personnel.
Depending on the structure and the operation of the distribution grid several dangers exist:
– In case of maintenance work in a distribution grid, personnel may be placed in danger if the deacti-
vated part of the grid remains live as an island. This is especially the case if not all safety rules are
followed.
– If fast auto-reclosure is used in a distribution grid and the deactivated part of the grid remains live
as an island, reclosure will likely happen during phase displacement which might cause damage to
rotating machinery on the grid.
– In the event of a fault in a medium voltage grid, the faulty part of the grid is disconnected. If the
fault has a significant resistance, the deactivated part of a medium-voltage grid remains live as an
island. Depending on the type of fault, but explicitly in case of a fault in the transformer, dangerous
medium voltage might be accessible or even present in low-voltage appliances.
Especially for the last example very fast disconnection of the generating units to cause collapse of the
forming island is necessary. At the same time any island formation detection method may cause false
tripping. The industry is therefore in constant research to develop methods that are fast and reliable
and at the same time reliably prevent false tripping.
Enhanced island detection method
The enhanced island detection of KACO new energy, employs a strategy to reliably detect island for-
mation that is based on the characteristic differences between an interconnected grid and an islanded
grid, thus ensuring reliable fast detection and prevention of false tripping.
An interconnected grid is dominated by rotating machinery, as a consequence frequency is proportio-
nal to active power balance and voltage is proportional to reactive power balance. In contrast an islan-
ded grid behaves like a resonant circuit, as a consequence frequency is proportional to reactive power
balance and voltage is proportional to active power balance. The active enhanced island detection
method detects this difference by monitoring the behaviour of the grid. The enhanced island detection
is monitoring the natural fluctuation of the grid frequency and injects a minimal reactive power propor-
tional to the rate of change of frequency. In the moment of formation of an island the connected power
systems is closing a positive feedback loop what allows the inverter to detect the changed situation
and to disconnect. In case of formation of an island, the inverter disconnects within some 100 ms, well
below 1000 ms.
Kaco blueplanet 29.0TL3
Specifications | 10
AVISO: The power ramp allows a moderate increase of the
Performance possible
Gradient of power limit. The maximum power limit increase to 100% of
nominal power with the gradient specified.
Soft start ramp up is activated for every connection of the inverter to
the grid
Soft start ramp up is activated for the first connection of the inverter to
the grid on a particular day or after complete reboot of the inverter (AC
and DC disconnected)
Soft start ramp up is activated for connection of the inverter to the grid
after trip of the internal interface protection or via the external grid pro-
tection port (Powador-protect)
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