ABB Relion 670 Series Product Manual page 27

Generator protection REG670
Version 2.2
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.
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
Hitachi Power Grids
SEMOD143246-17 v7
GUID-BF2F7D4C-F579-4EBD-9AFC-7C03296BD5D4 v8
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with current transformers. The protection function
performs a simple summation of the currents of the two
channels I3P1 and I3P2.
Loss of excitation LEXPDIS
There are limits for the under-excited operation of a
synchronous machine. A reduction of the excitation
current weakens the coupling between the rotor and the
stator. The machine may lose the synchronism and start
to operate like an induction machine. Then, the reactive
power consumption will increase. Even if the machine
does not loose synchronism it may not be acceptable to
operate in this state for a long time. Reduction of
excitation increases the generation of heat in the end
region of the synchronous machine. The local heating
may damage the insulation of the stator winding and
the iron core.
To prevent damages to the generator it should be
tripped when excitation is lost.
Sensitive rotor earth fault protection, injection
based ROTIPHIZ
The sensitive rotor earth fault protection (ROTIPHIZ) is
used to detect earth faults in the rotor windings of
generators. ROTIPHIZ is applicable for all types of
synchronous generators.
To implement the above concept, a separate injection
box is required. The injection box generates a square
wave voltage signal at a certain preset frequency which
is fed into the rotor winding.
The magnitude of the injected voltage signal and the
resulting injected current is measured through a
resistive shunt located within the injection box. These
two measured values are fed to the IED. Based on these
two measured quantities, the protection IED determines
the rotor winding resistance to ground. The resistance
value is then compared with the preset fault resistance
alarm and trip levels.
The protection function can detect earth faults in the
entire rotor winding and associated connections.
Requires injection unit REX060 and a coupling capacitor
unit REX061 for correct operation.
100% stator earth fault protection, injection based
STTIPHIZ
The 100% stator earth-fault protection (STTIPHIZ ) is
used to detect earth faults in the stator windings of
generators and motors. STTIPHIZ is applicable for
generators connected to the power system through a
unit transformer in a block connection. An independent
signal with a certain frequency different from the
generator rated frequency is injected into the stator
circuit. The responce of this injected signal is used to
detect stator earth faults.
1MRK 502 074-BEN M
SEMOD151269-4 v9
GUID-9D60105D-44C8-4FB1-AD63-C4D3631BC99E v2
GUID-A9BF9D69-2179-441C-A6C7-69EF0F55DD61 v4
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