6.3.6
Monitored data
Table 59:
GENPDIF Monitored data
Name
Type
Values (Range)
Unit
Description
IDL1MAG
REAL
-
A
Fund. freq. differential
current, phase L1; in
primary A
IDL2MAG
REAL
-
A
Fund. freq. differential
current, phase L2; in
primary A
IDL3MAG
REAL
-
A
Fund. freq. differential
current, phase L3; in
primary A
IDNSMAG
REAL
-
A
Negative Sequence
Differential current; in
primary Amperes
IBIAS
REAL
-
A
Magnitude of the
common Bias current; in
primary Amperes
6.3.7
Operation principle
The task of Generator differential protection GENPDIF is to determine whether a fault
is within the protected zone, or outside the protected zone. The protected zone is
delimited by the position of current transformers, as shown in figure
.
IEC06000430-2-en.vsd
IEC06000430 V2 EN
Figure 48:
Position of current transformers; the recommended (default)
orientation
If the fault is internal, the faulty generator must be quickly tripped, that is,
disconnected from the network, the field breaker tripped and the agent to the prime
mover interrupted.
GENPDIF function always uses reference (default) directions of CTs towards the
protected generator as shown in figure
. Thus, it always measures the currents on the
two sides of the generator with the same reference direction towards the generator
windings. With the orientation of CTs as in figure
, the difference of currents
flowing in, and out, of a separate stator winding phase is simply obtained by
summation of the two currents fed to the differential protection function.
Numerical IEDs have brought a large number of advantages and new functionality to
the protective relaying. One of the benefits is the simplicity and accuracy of
calculating symmetrical components from individual phase quantities. Within the
firmware of a numerical IED, it is no more difficult to calculate negative-sequence
Section 6
1MRK502052-UEN B
Differential protection
150
Technical manual
Summary of Contents for Relion REG670
Page 1: ...Relion 670 series Generator protection REG670 2 0 IEC Technical manual ...
Page 2: ......
Page 44: ...38 ...
Page 58: ...52 ...
Page 80: ...74 ...
Page 106: ...100 ...
Page 482: ...476 ...
Page 548: ...542 ...
Page 570: ...564 ...
Page 600: ...594 ...
Page 608: ...602 ...
Page 630: ...624 ...
Page 862: ...856 ...
Page 1094: ...1088 ...
Page 1226: ...1220 ...
Page 1250: ...1244 ...
Page 1297: ...1291 ...