ABB Relion 670 Series RES670, Technical Manual

Page: 265 / 888

Figure 80 illustrates the low forward power and reverse power protection with
underpower and overpower functions respectively. 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%.
When IED with a metering class input CTs is used pickup can be set to more sensitive
value (e.g.0,5% or even to 0,2%).
Underpower IED Overpower IED
Q Q
P P
Tripping point
without
turbine torque
Margin Margin
Trip
Line
Trip
Line
Tripping point
without
turbine torque
ANSI06000315-1-en.vsd
ANSI06000315 V1 EN
Figure 80: Reverse power protection with underpower IED and overpower IED
8.7.3 Function block
ANSI07000028-2-en.vsd
GOPPDOP (32)
I3P*
V3P*
BLOCK
BLOCK1
BLOCK2 TRIP
TRIP1
TRIP2
PICKUP
PICKUP1
PICKUP2
P
PPERCENT
Q
QPERCENT
ANSI07000028 V2 EN
Figure 81: GOPPDOP (32) function block
1MRK 511 365-UUS A
Section 8
Current protection
Phasor measurement unit RES670 2.1 ANSI 259
Technical manual