Hitachi Relion 670 Series Product Manual page 40

Line differential protection RED670
Version 2.2
directionality to forward, and five zone with directionality
independently settable to forward/reverse/non-directional.
The operation of the phase-selection is primarily based on a
current change criteria (i.e. delta quantities), however there
is also a phase selection criterion operating in parallel
which bases its operation on voltage and current phasors
exclusively. Additionally, the directional element provides a
fast and correct directional decision under difficult operating
conditions, including close-in three-phase faults,
simultaneous faults and faults with only zero-sequence in-
feed.
During phase-to-earth faults on heavily loaded power lines
there is an adaptive load compensation algorithm that
prevents overreaching of the distance zones in the load
exporting end, improving the selectivity of the function. This
also reduces underreach in the importing end.
The ZMFPDIS function is also equipped with the parallel
line mutual coupling compensation feature based on the
parallel line residual current.
High speed distance protection for series comp.
lines, quad and mho characteristic ZMFCPDIS
The high speed distance protection (ZMFCPDIS) provides a
sub-cycle, down towards a half-cycle operate time. Its
seven zone, full scheme protection concept is entirely
suitable in applications with single-phase autoreclosing.
High speed distance protection ZMFCPDIS is fundamentally
the same function as ZMFPDIS but provides more flexibility
in zone settings to suit more complex applications, such as
series compensated lines. In operation for series
compensated networks, the parameters of the directional
function are altered to handle voltage reversal.
Each measurement zone is designed with the flexibility to
operate in either quadrilateral or mho characteristic mode.
This can even be decided separate for the phase-to-earth or
phase-to-phase loops. The seven zones can operate either
independent of each other, or their start can be linked (per
zone) through the phase selector or the first starting zone.
This can provide fast operate times for evolving faults.
The operation of the phase-selection is primarily based on a
current change criteria (i.e. delta quantities), however there
is also a phase selection criterion operating in parallel
which bases its operation on voltage and current phasors
exclusively. Additionally the directional element provides a
fast and correct directional decision under difficult operating
conditions, including close-in three-phase faults,
simultaneous faults and faults with only zero-sequence in-
feed.
During phase-to-earth faults on heavily loaded power lines
there is an adaptive load compensation algorithm that
prevents overreaching of the distance zones in the load
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exporting end, improving the selectivity of the function. This
also reduces underreach in the importing end.
The ZMFCPDIS function has another directional element
with phase segregated outputs STTDFwLx and STTDRVLx
(where, x = 1-3) based on the transient components. It
provides directionality with high speed, dependability and
security, which is also suitable for extra high voltage and
series compensated lines where the fundamental frequency
signals are distorted.
The ZMFCPDIS function is also equipped with the parallel
line mutual coupling compensation feature based on the
parallel line residual current.
Power swing detection, blocking and unblocking
ZMBURPSB
Power swings may occur after disconnection of heavy loads
or trip of big generation plants.
Power swing detection, blocking and unblocking function
(ZMBURPSB ) is used to detect power swings and initiate
blocking of all distance protection zones.
Also, fault identification and its classification for various
types of fault occurrences during the power swing
are available in the ZMBURPSB function. So, six measuring
loops used in each distance protection zone, if blocked
during power swing, can be unblocked/released for distance
measurement depending upon the fault type and thereby,
reliable fault clearance can be achieved for faults during
power swing.
It is still possible to inhibit the ZMBURPSB function for
earth-fault currents during a power swing without activating
power swing unblocking functionality.
Power swing logic PSLPSCH
Power Swing Logic (PSLPSCH) provides possibility for
selective tripping of faults on power lines during system
oscillations (power swings or pole slips), when the distance
protection function should normally be blocked. The
complete logic consists of two different parts:
• Communication and tripping part: provides selective
tripping on the basis of special distance protection zones
and a scheme communication logic, which are not
blocked during the system oscillations.
• Blocking part: blocks unwanted operation of
instantaneous distance protection zone 1 for oscillations,
which are initiated by faults and their clearing on the
adjacent power lines and other primary elements.
Pole slip protection PSPPPAM
Sudden events in an electric power system such as large
changes in load, fault occurrence or fault clearance, can
cause power oscillations referred to as power swings. In a
non-recoverable situation, the power swings become so
severe that the synchronism is lost, a condition referred to
1MRK 505 379-BEN R
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SEMOD143246-17 v7
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