ABB Relion 670 Series Product Manual page 36

Bay control REC670
Version 2.2
• Remote command or binary trigger-based
compensation for natural unbalance current
• Insensitive to system unbalances
• The function provides phase segregated warning,
alarm and trip signals along with the general warning,
alarm and trip signal based on independent set levels
• Two timer modes for trip signal-Definite time and
programmable IDMT delay curve
• Unwanted operation of the function, for example,
capacitor bank de-energization can be inhibited by
activating a binary signal
• Secure operation of function against minimum phase
currents
Phase voltage differential based capacitor bank
unbalanced protection SCPDPTOV
The phase voltage differential based capacitor bank
unbalanced protection (SCPDPTOV) function protects
the shunt capacitor bank(SCB) from the unbalance due
to internal faults in elements or units. The SCPDPTOV
function can be applied to grounded and ungrounded
capacitor bank configurations, where the three-phase
bus and tap voltage measurements are available.
The main features of the function are,
• It can be applied for both single WYE and double WYE,
grounded and ungrounded capacitor bank
configurations.
• Continuous monitoring of voltage ratio to overcome
the natural unbalance.
• The voltage ratio can be settable or can be triggered
remotely to be updated it with continuously calculated
values.
• Binary signal indication, when the percentage
variation of calculated voltage and stored voltage
ratios exceeds the settable limit.
• Function provides phase segregated warning, alarm
and trip signals along with a general warning, alarm
and trip signal based on independent set levels.
• Reliable warning and alarm signals are generated,
stability of alarm and the warning signal is ensured
with settable time delay.
• Two timer modes for trip signal-Definite time and
programmable IDMT delay curve.
• Unwanted operation of the function, for example,
capacitor bank de-energization can be inhibited by
activating a binary signal.
Voltage unbalance protection for shunt capacitor
bank SCUVPTOV
The voltage unbalance protection for shunt capacitor
bank (SCUVPTOV) function is used to protect an
ungrounded single and double WYE shunt capacitor
bank with the single neutral voltage measurement. It
operates when the differential voltage between
36
GUID-F1EA4875-9014-4118-BBAE-80FBB707E768 v1
GUID-D9BA5FF8-1A61-46BB-B705-51C9C40ED5D5 v1
© Copyright 2017 Hitachi Power Grids. All rights reserved
measured neutral voltage and zero sequence voltage of
the bus is larger than the set operate voltage.
The main features of the function are,
• It is insensitive to system unbalance
• Influence of any natural unbalance in the capacitor
bank can be compensated
• Evaluation of the voltage unbalance compensation
factor can be triggered by either binary input or over
LHMI or MMS command
• Function operation can be blocked through binary
input during unwanted operation, for example, SCB
de-energization
• Minimum bus voltage check for secure operation
• Function has warning, alarm and trip levels
• Function trip signal can be delayed by definite timer
or based on a programmable curve and warning and
alarm have definite time delays
11. Frequency protection
Underfrequency protection SAPTUF
Underfrequency occurs as a result of a lack of
generation in the network.
Underfrequency protection (SAPTUF) measures
frequency with high accuracy, and is used for load
shedding systems, remedial action schemes, gas turbine
startup and so on. Separate definite time delays are
provided for operate and restore.
SAPTUF is provided with undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three
phase-neutral voltages to be connected.
Overfrequency protection SAPTOF
Overfrequency protection function (SAPTOF) is
applicable in all situations, where reliable detection of
high fundamental power system frequency is needed.
Overfrequency occurs because of sudden load drops or
shunt faults in the power network. Close to the
generating plant, generator governor problems can also
cause over frequency.
SAPTOF measures frequency with high accuracy, and is
used mainly for generation shedding and remedial
action schemes. It is also used as a frequency stage
initiating load restoring. A definite time delay is
provided for operate.
SAPTOF is provided with an undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three
phase-neutral voltages to be connected.
1MRK 511 404-BEN N
M13349-3 v13
M14953-3 v12
Hitachi Power Grids