ABB Relion 670 Series Technical Reference Manual page 478

Section 7
Current protection
7.11.2
472
Principle of operation
A simplified scheme showing the principle of the power protection function is shown
in figure 239. The function has two stages with individual settings.
Chosen current
phasors
Complex
power
Chosen voltage
calculation
phasors
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 233.
Table 233: Complex power calculation
Mode
Set value:
A, B, C
Arone
PosSeq
AB
Table continues on next page
P
Derivation of S( angle)
S( composant)
in Char angle
Q
Formula used for complex power calculation
= ×
S V I
A
EQUATION2055-ANSI V1 EN
=
S V
AB
EQUATION2056-ANSI V1 EN
= ×
S 3 V
PosSeq
EQUATION2057-ANSI V1 EN
= ×
S V
AB
EQUATION2058-ANSI V1 EN
1MRK505222-UUS C
t TRIP 1
S( angle) <
Power1
0
PICKUP1
S( angle) < t TRIP2
Power2
0
PICKUP2
P = POWRE
Q = POWIM
ANSI06000438-2-en.vsd
* * *
+ × + ×
V I V I
A B B C C
(Equation 97)
* *
× - ×
I V I
A BC C
(Equation 98)
*
×
I
PosSeq
(Equation 99)
* *
-
( I I )
A B
(Equation 100)
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