Table of Contents
Line distance protection REL670
Version 2.2
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
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.
Hitachi Energy
GUID-DB043AB6-E571-4DCB-B899-663D13AFDE2E v1
© 2017 - 2022 Hitachi Energy. All rights reserved
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.
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
1MRK 506 372-BEN Q
SEMOD131350-4 v5
SEMOD143246-17 v7
GUID-BF2F7D4C-F579-4EBD-9AFC-7C03296BD5D4 v8
39
Table of Contents
