ABB RELION REX640 - Excitation fault detection

Table 1344: Voting algorithm for detecting fueling faults
Type of fault Fault detection criteria Output activation
Over fueling fault
Number of generators in parallel with same gover-
nor mode >= 3
AND
MAX(P1, P2, … P8) – MIN(P1, P2 … P8) < Max P Dev
Vot
(This check ensures that the network generators,
excluding local generator, are operating with simi-
lar load)
AND
P > MAX (P1, P2… P8) +
Max P Dev Vot
(This is to check if the local generator load (P) is
deviating significantly from other generators in the
same network)
OV_FUEL_FLT
Under fueling fault
Number of generators in parallel with same gover-
nor mode >= 3
AND
MAX(P1, P2, … P8) – MIN(P1, P2 … P8) < Max P Dev
Vot
AND
P < MIN (P1, P2… P8) - Max P Dev Vot
UN_FUEL_FLT
If the generator is identified as faulty by the Correlation algorithm, then the
generator is removed from the Voting algorithm. Similarly if a network generator
is communicated to be faulty via inputs GEN1_DATA … GEN8_DATA, or if the quality
of any of the inputs GEN1_DATA … GEN8_DATA is unreliable, then that generator
is also removed from the Voting algorithm. This prevents misdiagnosis by Voting
algorithm in the event that several generators should suffer from a common mode
failure.
Excitation fault detection
This module detects problems with the generator excitation or AVR, which result
in excessive reactive power (over excitation) or insufficient reactive power (under
excitation) production by the generator.
As in Fueling fault detection block, the excitation faults are also detected by
Correlation algorithm and Voting algorithm. The module activates OV_EXCT_FLT in
case of over excitation fault detection and UN_EXCT_FLT output in case of under
excitation fault. These two signals are available as outputs. Once an excitation fault
is detected, the module initiates the Control logic module.
If the input AVR_MODE_DRP is FALSE, indicating that the automatic voltage regulator
is not in droop mode, then the module is disabled. If the quality status of the
local reactive power input is faulty, then the module is disabled and INT_BLKD
output is activated. If generator present in the same subnetwork is faulty or if
the quality status of reactive power of a generator is faulty, then that generator
is removed from comparison in the Fueling fault detection module. INT_BLKD_STS
1MRS759142 F
Condition monitoring functions
REX640
Technical Manual
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