7.11.2
Principle of operation
A simplified scheme showing the principle of the power protection function is shown
in figure
. The function has two stages with individual settings.
Chosen current
phasors
Chosen voltage
phasors
Complex
power
calculation
P
Derivation of
S( composant)
in Char angle
S( angle)
S( angle) <
Power1
t
TRIP 1
PICKUP1
Q
P = POWRE
Q = POWIM
S( angle) <
Power2
TRIP2
PICKUP2
0
t
0
ANSI06000438-2-en.vsd
ANSI06000438 V2 EN
Figure 239:
Simplified logic diagram of the power protection function
The function will use voltage and current phasors calculated in the pre-processing
blocks. The apparent complex power is calculated according to chosen formula as
shown in table
.
Table 233:
Complex power calculation
Set value:
Mode
Formula used for complex power calculation
A, B, C
*
*
*
A
A
B
B
C
C
S V
I
V
I
V
I
=
×
+
×
+
×
EQUATION2055-ANSI V1 EN
(Equation 97)
Arone
*
*
AB
A
BC
C
S V
I
V
I
=
×
-
×
EQUATION2056-ANSI V1 EN
(Equation 98)
PosSeq
*
3
PosSeq
PosSeq
S
V
I
= ×
×
EQUATION2057-ANSI V1 EN
(Equation 99)
AB
*
*
(
)
AB
A
B
S V
I
I
=
×
-
EQUATION2058-ANSI V1 EN
(Equation 100)
Table continues on next page
Section 7
1MRK505222-UUS C
Current protection
472
Technical reference manual
Summary of Contents for Relion 670 series
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