ABB Relion 670 Series Applications Manual page 205

1MRK 511 401-UUS F
Gas turbines usually do not require reverse power protection.
Figure 93
The underpower IED gives a higher margin and should provide better dependability. On the other
hand, the risk for unwanted operation immediately after synchronization may be higher. One
should set the underpower IED to trip if the active power from the generator is less than about
2%. One should set the overpower IED to trip if the power flow from the network to the generator
is higher than 1%.
Operate
Line
Margin
Operating point
without
turbine torque
IEC06000315 V2 EN-US
Figure 93: Reverse power protection with underpower IED and overpower IED
8.13.3 Setting guidelines
GlobalBaseSel : Selects the global base value group used by the function to define IBase , VBase and
SBase . Note that this function will only use IBase value.
Operation : With the parameter Operation the function can be set Enabled / Disabled .
Mode : The voltage and current used for the power measurement. The setting possibilities are
shown in table 28.
Table 28: Complex power calculation
Set value
A,B,C
Arone
PosSeq
A,B
Table continues on next page
Bay control REC670
Application manual
illustrates the reverse power protection with underpower IED and with overpower IED.
Underpower IED
Q
Operate
Line
Margin
P
Operating point
without
turbine torque
Mode
© Copyright 2017 ABB. All rights reserved
Overpower IED
Q
P
IEC06000315-2-en.vsd
Formula used for complex power calculation
*
= × +
S V I V
A A
EQUATION2038 V1 EN-US
*
-
= ×
S V I
A
AB
EQUATION2039 V1 EN-US
= × ×
S 3 V I
PosSeq PosSeq
EQUATION2040 V1 EN-US
*
-
= ×
S V (I
AB A
EQUATION2041 V1 EN-US
* *
× + ×
I V I
B B C C
*
×
V I
C
BC
*
*
)
I
B
Section 8
Current protection
SEMOD172150-4 v7
(Equation 82)
(Equation 83)
(Equation 84)
(Equation 85)
199