Power swing detection ZMRPSB
Power swings may occur after disconnection of heavy loads or
trip of big generation plants.
Power swing detection function (ZMRPSB ) is used to detect
power swings and initiate block of all distance protection zones.
Occurrence of earth-fault currents during a power swing
inhibits the ZMRPSB function, to allow fault clearance.
Power swing logic PSLPSCH
Power Swing Logic (PSLPSCH) is a complementary function to
Power Swing Detection (ZMRPSB) function. It 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.
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 fault based on the selected phase preference.
A number of different phase preference combinations are
available for selection.
PPL2PHIZ provides an additional phase selection criteria,
namely under voltage criteria, suitable for 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 is difficult to find
appropriate under-voltage or phase selection settings. If
PPL2PHIZ is unable to detect both faulty phases, then it is not
possible to provide preference. The distance protection will still
be released however, without preference. The final result might
be that both faulty feeders are operated. In other words,
operation is prioritized over strict adherence to preference.
Automatic switch onto fault logic, voltage and current based
ZCVPSOF
Automatic switch onto fault logic (ZCVPSOF) is a function that
gives an instantaneous trip at closing of breaker onto a fault. A
dead line detection check is provided to activate the function
when the line is dead.
1MRK 506 372-BEN -
Line distance protection REL670 2.2
Product version: 2.2
30 ABB
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