Directional Impedance Element For Mho Characteristic Zdmrdir; Mho Impedance Supervision Logic Zsmgapc; Faulty Phase Identification With Load Encroachment Fmpspdis - ABB RED670 Product Manual

Line differential protection RED670 ANSI
Customized
Product version: 1.2
jX
Operation area Operation area
Operation area
No operation area No operation area
IEC07000117 V1 EN
Figure 8. Load encroachment influence on the offset mho
characteristic
The distance protection zones can operate, independent of
each other, in directional (forward or reverse) or non-directional
mode (offset). This makes them suitable, together with different
communication schemes, for the protection of power lines and
cables in complex network configurations, such as parallel lines,
multi-terminal lines and so on.
The possibility to use the phase-to-ground quadrilateral
impedance characteristic together with the mho characteristic
increases the possibility to overcome eventual lack of sensitivity
of the mho element due to the shaping of the curve at remote
end faults.
The integrated control and monitoring functions offer effective
solutions for operating and monitoring all types of transmission
and sub-transmission lines.

Directional impedance element for Mho characteristic ZDMRDIR

The phase-to-ground impedance elements can be optionally
supervised by a phase unselective directional function (phase
unselective, because it is based on symmetrical components).

Mho impedance supervision logic ZSMGAPC

The Mho impedance supervision logic (ZSMGAPC) includes
features for fault inception detection and high SIR detection. It
also includes the functionality for loss of potential logic as well
as for the pilot channel blocking scheme.
ZSMGAPC can mainly be decomposed in two different parts:
1. A fault inception detection logic
2. High SIR detection logic
ABB
R
en07000117.vsd

Faulty phase identification with load encroachment FMPSPDIS

(21)
The operation of transmission networks today is in many cases
close to the stability limit. Due to environmental considerations
the rate of expansion and reinforcement of the power system is
reduced, for example difficulties to get permission to build new
power lines. The ability to accurate and reliable classifying the
different types of fault so that single phase tripping and
autoreclosing can be used plays an important roll in this matter.
The phase selection function is design to accurately select the
proper fault loop(s) in the distance function dependent on the
fault type.
The heavy load transfer that is common in many transmission
networks may in some cases interfere with the distance
protection zone reach and cause unwanted operation.
Therefore the function has a built in algorithm for load
encroachment, which gives the possibility to enlarge the
resistive setting of the measuring zones without interfering with
the load.
The output signals from the phase selection function produce
important information about faulty phase(s), which can be used
for fault analysis as well.
Distance protection zone, quadrilateral characteristic, separate
settings ZMRPDIS, ZMRAPDIS (21)
The line distance protection is up to five zone full scheme
protection with three fault loops for phase-to-phase faults and
three fault loops for phase-to-ground fault for each of the
independent zones. Individual settings for each zone in resistive
and reactive reach gives flexibility for use as back-up protection
for transformer connected to overhead lines and cables of
different types and lengths.
Mho alternative quadrilateral characteristic is available.
ZMRPDIS (21) together with Phase selection, quadrilateral
characteristic with settable angle FRPSPDIS (21) has
functionality for load encroachment, which increases the
possibility to detect high resistive faults on heavily loaded lines,
as shown in figure 6.
1MRK505226-BUS D
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