ABB ret650, Technical Manual

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tool PCM600. The inputs Qx_EXy on the interlocking modules are used to add these
specific conditions.
The input signals EXDU_xx shall be set to true if there is no transmission error at the
transfer of information from other bays. Required signals with designations ending in
TR are intended for transfer to other bays.
12.3 Voltage control
12.3.1 Functionality
Automatic voltage control for tap changer TR8ATCC and Tap changer control and
supervision, 6 binary inputs TCMYLTC are used for control of power transformers
with a on-load tap changer. The functions provide automatic regulation of the voltage
on the secondary side of transformers or alternatively on a load point further out in the
network.
Control of a single transformer, as well as control of up to two transformers within a
single RET650, or parallel control of up to four transformers in two or even four
separate RET650 is possible. Note that the last alternative is achieved by using the
GOOSE interbay communication on the IEC 61850-8-1 protocol. For parallel control
of power transformers, three alternative methods are available, the master-follower
method, the circulating current method and the reverse reactance method.
Voltage control includes many extra features such as possibility of to avoid
simultaneous tapping of parallel transformers, extensive tap changer monitoring
including contact wear and hunting detection, monitoring of the power flow in the
transformer so that for example, the voltage control can be blocked if the power
reverses etc.
In manual operating mode it is possible to give raise- or lower-commands to the load
tap changer from the local HMI. Such facilities are pre-defined in the factory.
The Automatic voltage control for tap changer TR8ATCC function controls the
voltage on the LV side of a transformer either automatically or manually. The
automatic control can be either for a single transformer, or for a group of parallel
transformers.
The Tap changer control and supervision, 6 binary inputs (TCMYLTC) gives the tap
commands to the tap changer, and supervises that commands are carried through
correctly. It has built-in extensive possibilities for tap changer position measurement,
as well as supervisory and monitoring features. This is used in the voltage control and
can also give information about tap position to the transformer differential protection.
12.3.2 Automatic voltage control for tapchanger, parallel control
TR8ATCC
1MRK 504 135-UEN A
Section 12
Control
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Technical manual