Accidental Energizing Protection For Synchronous Generator Aegpvoc - ABB REG670 Applications Manual

1MRK 502 071-UEN -
9.13
9.13.1
9.13.2
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Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
Accidental energizing protection for synchronous
generator AEGPVOC
Identification
Function description
Accidental energizing protection for
synchronous generator
Application
Operating error, breaker head flashovers, control circuit malfunctions or a
combination of these causes results in the generator being accidentally energized
while offline. Three-phase energizing of a generator that is at standstill or on turning
gears causes it to behave and accelerate similarly to an induction motor. The
generator, at this point, essentially represent sub-transient reactance to the system and
it can draw one to four per unit current depending upon the equivalent system
impedance. This high current may thermally damage the generator in a few seconds.
Accidental energizing protection for synchronous generator AEGPVOC monitors
maximum phase current and maximum phase-to-phase voltage of the generator. In its
basis it is "voltage supervised over current protection". When generator voltage fails
below preset level for longer than preset time delay an overcurrent protection stage is
enabled. This overcurrent stage is intended to trip generator in case of an accidental
energizing. When the generator voltage is high again this overcurrent stage is
automatically disabled.
Setting guidelines
I>: Level of current trip level when the function is armed, that is, at generator
standstill, given in % of IBase. This setting should be based on evaluation of the
largest current that can occur during the accidental energizing: I
can be calculated as:
U
N
3
=
I
energisation
'' + +
X X Z
d T network
EQUATION2282 V2 EN
Current protection
IEC 61850 IEC 60617
identification identification
AEGPVOC U<I>
Section 9
ANSI/IEEE C37.2
device number
50AE
. This current
energisation
(Equation 238)
393