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2019.02 / p
Electric Power Generation
46
Installation and maintenance
D510 C
Digital voltage regulator
4243 en -
3.6 - Dead bus synchronization
The principle is to synchronize the
generators while in standstill and then start
them simultaneously. The system should
ensure a limited reactive power sharing
between the generators. The authorization
to switch to the regulation mode may be
given either automatically or via an external
command.
Note:
the power plant manager must
ensure that all the dead bus synchronized
gensets correctly started and Leroy-Somer
is not responsible of huge reactive power
absorption by a genset which start sequence
failed during the dead bus synchronization
(DBS) sequence.
3.6.1 - DBS Automatic management
In this case, the D510C manages the pre-
excitation and the switching to the voltage
regulation mode without any external
command. To do so, the “Start on
Threshold » function is used as given below.
Note:
it is mandatory to have the same
activation threshold on the whole
synchronized generators. As regards the
initial PWMs, they can be set according to
the excitation type, e.g 5% for generator
with PMG excitation and 15% for those with
AREP excitation.
Step 1:
each D510C pre-excites the
alternator to which it is connected following
the initial PWM. Each generator will have its
voltage gradually increased according to
the genset speed.
Step 2:
when the activation threshold is
reached (e.g 200V), all the D510C will
switch to voltage regulation. The voltage will
gradually reach the final reference value
following a slope depending on the selected
Soft Start value.
Note:
here also, it is mandatory to have the
same « Soft Start » on all the D510C used in
the application.
3.6.2 - DBS management via external
command
Here, an external command such as a digital
input or CANBUS flags is used. The pre-
excitation of each generator is done with a
constant value (not necessary to have the
same excitation reference when different
generators sizes are used) and when the
conditions are respected, a command is
sent to ensure the switching to the regulation
mode. The approach involving the CANBUS
is presented below.
Step 1:
the genset controller sends the
command to the D510C to enable the
Manual mode regulation (parameter 5.49)
with a constant reference (parameter 5.33).
During this phase, reactive power sharing
may occur, but it can be minimized thanks to
appropriate definition of the excitation
current references on each generator.