ABB Relion 670 Series Product Manual page 36

Line distance protection REL670
Version 2.2
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 as pole slipping. The main purpose of the
pole slip protection (PSPPPAM) is to detect, evaluate,
and take the required action for pole slipping
occurrences in the power system.
Out-of-step protection OOSPPAM
The out-of-step protection (OOSPPAM ) function in the
IED can be used for both generator protection and as
well for line protection applications.
The main purpose of the OOSPPAM function is to detect,
evaluate, and take the required action during pole
slipping occurrences in the power system.
The OOSPPAM function detects pole slip conditions and
trips the generator as fast as possible, after the first
pole-slip if the center of oscillation is found to be in
zone 1, which normally includes the generator and its
step-up power transformer. If the center of oscillation is
found to be further out in the power system, in zone 2,
more than one pole-slip is usually allowed before the
generator-transformer unit is disconnected. A
parameter setting is available to take into account the
circuit breaker opening time. If there are several out-of-
step relays in the power system, then the one which
finds the center of oscillation in its zone 1 should
operate first.
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SEMOD131350-4 v5
SEMOD143246-17 v7
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Two current channels I3P1 and I3P2 are available in
OOSPPAM function to allow the direct connection of two
groups of three-phase currents; that may be needed for
very powerful generators, with stator windings split into
two groups per phase, when each group is equipped
with current transformers. The protection function
performs a simple summation of the currents of the two
channels I3P1 and I3P2.
Phase preference logic PPLPHIZ
The optional phase preference logic (PPLPHIZ) is used
with the ZMQPDIS and FDPSPDIS distance protection.
The main purpose of this function is to provide a
selective tripping for cross-country faults in isolated or
high impedance-earthed networks.
Phase preference logic PPL2PHIZ
The Phase preference logic function (PPL2PHIZ) is used
with the high speed distance protection, quad and mho
characteristic (ZMFPDIS). It is intended to be used in
isolated or high impedance earthed networks where
there is a requirement to operate on only one of the
faulty lines during a cross-country fault. It can be used
without preference to restrain operation for single earth
faults with a delayed zero-sequence current release.
For cross-country faults, the logic selects either the
leading or lagging phase-earth loop for measurement. It
initiates operation on the preferred phase based on the
selected phase preference scheme. A number of
different phase preference schemes are available.
PPL2PHIZ provides an additional phase selection
criteria, namely under voltage criteria, suitable for phase
selection during cross-country faults. In radial networks,
where there is no fault current in the phase with the
external fault, current or impedance based phase
selection methods become ineffective. Hence, only
voltage can be used for phase selection. The phase
selection result will be the same for all bays on a bus
since the voltage is the same, which is an important
condition for operating with phase preference.
In meshed and stronger networks, it may be difficult to
find appropriate under-voltage settings for phase
selection. Therefore an automatic phase selection logic
is made available which works in parallel with a set
under-voltage criterion in order to detect the two faulty
phases even for complex networks. If for any reason the
PPL2PHIZ is unable to detect the two faulty phases, then
after a short time delay all three phase-to-earth loops of
the distance protection will be released for operation.
The final result might be that both faulty feeders are
disconnected. In other words, protection operation is
prioritized over strict adherence to preference.
1MRK 506 372-BEN M
SEMOD153619-5 v3
GUID-39785DEB-E5D7-447C-977B-9E940CA8E774 v2
Hitachi Power Grids