Impedance Protection - ABB Relion 670 Series Product Manual

Generator protection REG670
Version 2.2
comparison criterion. This gives excellent sensitivity and
stability during through faults.
REFPDIF can also protect autotransformers. Five
currents are measured at the most complicated
configuration as shown in Figure 5.
YNdx
CT
d
Y
CB CB
CT
IED
The most typical
application
IEC05000058-2 V1 EN-US
Figure 5. Examples of applications of the REFPDIF

5. Impedance protection

Full-scheme distance measuring, Mho characteristic
ZMHPDIS
The numerical mho line distance protection is an up to
four zone full scheme protection for back-up detection
of short circuit and earth faults.
The full scheme technique provides back-up protection
of power lines with high sensitivity and low requirement
on remote end communication.
The zones have fully independent measuring and
settings, which gives high flexibility for all types of lines.
Built-in selectable zone timer logic is also provided in
the function.
The function can be used as under impedance back-up
protection for transformers and generators.
Directional impedance element for Mho
characteristic ZDMRDIR
The phase-to-earth impedance elements can be
optionally supervised by a phase unselective directional
function (phase unselective, because it is based on
symmetrical components).
High speed distance protection, quadrilateral and
mho ZMFPDIS
The high speed distance protection (ZMFPDIS) provides
a sub-cycle, down towards a half-cycle operate time. Its
seven zone full scheme protection with three fault loops
for phase-to-phase faults and three fault loops for
phase-to-earth faults for each of the independent zones,
which makes the function suitable for applications with
single-phase autoreclosing.
26
CT CT
CB
CB
Autotransformer
CB CT
CB
CT
The most complicated
application - autotransformer
IEC05000058-2-en.vsd
SEMOD175459-4 v12
SEMOD175532-4 v2
GUID-2E34AB7F-886E-499F-8984-09041A89238D v10
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Each measurement zone is designed with the flexibility
to operate in either quadrilateral or mho characteristic
mode. This can be decided separately for the phase-to-
ground or phase-to-phase loops. Out of the seven zones,
one zone has fixed directionality to reverse, one zone
has fixed 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.
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-ground 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
1MRK 502 074-BEN M
GUID-C5C1ADD8-50A5-4485-848C-77D2222B56DC v9
Hitachi Power Grids