Multipurpose Protection; Secondary System Supervision - ABB Relion 670 Series Product Manual

ABB
Phasor measurement unit RES670
Pre-configured
Product version: 1.2
The operation is based on positive sequence
voltage measurement and requires two phase-
phase or three phase-neutral voltages to be
connected. For information about how to connect
analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines
Rate-of-change frequency protection SAPFRC
Rate-of-change frequency protection function
(SAPFRC) gives an early indication of a main
disturbance in the system. SAPFRC can be used
for generation shedding, load shedding and
remedial action schemes. SAPFRC can
discriminate between positive or negative change
of frequency.
SAPFRC 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. For information about how to
connect analog inputs, refer to Application
manual/IED application/Analog inputs/Setting
guidelines.

7. Multipurpose protection

General current and voltage protection CVGAPC
The General current and voltage protection
(CVGAPC) can be utilized as a negative sequence
current protection detecting unsymmetrical
conditions such as open phase or unsymmetrical
faults.
CVGAPC can also be used to improve phase
selection for high resistive earth faults, outside the
distance protection reach, for the transmission
line. Three functions are used, which measures
the neutral current and each of the three phase
voltages. This will give an independence from
load currents and this phase selection will be
used in conjunction with the detection of the earth
fault from the directional earth fault protection
function.

8. Secondary system supervision

Current circuit supervision CCSRDIF
Open or short circuited current transformer cores
can cause unwanted operation of many
protection functions such as differential, earth-
fault current and negative-sequence current
functions.
It must be remembered that a blocking of
protection functions at an occurrence of open CT
circuit will mean that the situation will remain and
extremely high voltages will stress the secondary
circuit.
Current circuit supervision (CCSRDIF) compares
the residual current from a three phase set of
current transformer cores with the neutral point
current on a separate input taken from another
set of cores on the current transformer.
A detection of a difference indicates a fault in the
circuit and is used as alarm or to block protection
functions expected to give unwanted tripping.
Fuse failure supervision SDDRFUF
The aim of the fuse failure supervision function
(SDDRFUF) is to block voltage measuring
functions at failures in the secondary circuits
between the voltage transformer and the IED in
order to avoid unwanted operations that
otherwise might occur.
The fuse failure supervision function basically has
three different algorithms, negative sequence and
zero sequence based algorithms and an
additional delta voltage and delta current
algorithm.
The negative sequence detection algorithm is
recommended for IEDs used in isolated or high-
impedance earthed networks. It is based on the
negative-sequence measuring quantities, a high
value of voltage 3U without the presence of the
2
negative-sequence current 3I
The zero sequence detection algorithm is
recommended for IEDs used in directly or low
impedance earthed networks. It is based on the
zero sequence measuring quantities, a high value
of voltage 3U without the presence of the
0
residual current 3I .
0
For better adaptation to system requirements, an
operation mode setting has been introduced
which makes it possible to select the operating
conditions for negative sequence and zero
sequence based function. The selection of
different operation modes makes it possible to
choose different interaction possibilities between
the negative sequence and zero sequence based
algorithm.
1MRK 511 266-BEN -
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