ABB Relion REC670 Applications Manual page 304

Section 13
Control
Of these alternatives, the first and the last require communication between the function
control blocks of the different transformers, whereas the middle alternative does not require
any communication.
The voltage control includes many extra features such as possibility to avoid simultaneous
tapping of parallel transformers, hot stand by regulation of a transformer within a parallel
group, with a LV CB open, compensation for a possible capacitor bank on the LV side bay of a
transformer, 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 and so on.
The voltage control function is built up by two function blocks which both are logical nodes in
IEC 61850-8-1:
• Automatic voltage control for tap changer, TR1ATCC for single control and TR8ATCC for
parallel control.
• Tap changer control and supervision, 6 binary inputs, TCMYLTC and 32 binary inputs,
TCLYLTC
Automatic voltage control for tap changer, TR1ATCC or TR8ATCC is a function designed to
automatically maintain the voltage at the LV-side side of a power transformer within given
limits around a set target voltage. A raise or lower command is generated whenever the
measured voltage, for a given period of time, deviates from the set target value by more than
the preset deadband value (degree of insensitivity). A time delay (inverse or definite time) is
set to avoid unnecessary operation during shorter voltage deviations from the target value,
and in order to coordinate with other automatic voltage controllers in the system.
TCMYLTC and TCLYLTC are an interface between the Automatic voltage control for tap
changer, TR1ATCC or TR8ATCC and the transformer load tap changer itself. More specifically
this means that it gives command-pulses to a power transformer motor driven load tap
changer and that it receives information from the load tap changer regarding tap position,
progress of given commands, and so on.
TCMYLTC and TCLYLTC also serve the purpose of giving information about tap position to the
transformer differential protection.
Control location local/remote
The tap changer can be operated from the front of the IED or from a remote place
alternatively. On the IED front there is a local remote switch that can be used to select the
operator place. For this functionality the Apparatus control function blocks Bay control
(QCBAY), Local remote (LOCREM) and Local remote control (LOCREMCTRL) are used.
Information about the control location is given to TR1ATCC or TR8ATCC function through
connection of the Permitted Source to Operate (PSTO) output of the QCBAY function block to
the input PSTO of the TR1ATCC or TR8ATCC function block.
Control Mode
The control mode of the automatic voltage control for tap changer function, TR1ATCC for
single control and TR8ATCC for parallel control can be:
• Manual
• Automatic
The control mode can be changed from the local location via the command menu on the local
HMI under Main menu/Control/Commands/TransformerVoltageControl(ATCC,90)/
TR1ATCC:x/TR8ATCC:x, or changed from a remote location via binary signals connected to the
MANCTRL, AUTOCTRL inputs on TR1ATCC or TR8ATCC function block.
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1MRK 511 358-UEN A
SEMOD159053-30 v3
SEMOD159053-35 v4
Application manual