ABB Relion 670 Series Technical Reference Manual page 841

1MRK505222-UUS C
13.8.3.2
Technical reference manual
Principle of operation
Compensated over and undervoltage protection (COUVGAPC, 59_27) function is
phase segregated and mainly used for local criteria check in Direct transfer trip. The
principle is to utilize local measured voltage and current to calculate the voltage at the
remote end of the line.
The main measured inputs to COUVGAPC (59_27) are three-phase voltage and
current signals. COUVGAPC (59_27)uses line resistance, reactance and line charging
capacitance to calculate the remote end voltage. It also takes the input for local shunt
reactor, connected at the line side of the line breaker, reactance value. The calculated
voltage is referred to as compensated voltage.
V3P
I3P
SWIPOS
voltage calculation
AND
EnShuntReactor
ANSI09000782 V1 EN
Figure 417: Logic diagram of Compensated over and undervoltage protection
(COUVGAPC, 59_27)
The formula used for calculation of compensated voltage is as follows:
V = V – (I – j x V
remote local local
Where:
V calculated voltage at the opposite side of line
remote
V measured local voltage
local
I measured local current
local
X reactance of local line connected shunt reactor, if applicable
sr
X half of equivalent reactance of line distributed capacitor
cp
Above calculated compensated voltage is compared to preset over and under voltage
levels set as percentage of base voltage VBase. If the calculated voltage exceeds setting
Over voltage
comparator
Compensated
Under voltage
comparator
/X + j x V
local sr local
Section 13
Scheme communication
t
t
ANSI09000782-1-en.vsd
/X ) x Z
cp setting
59 PU
59 Trip
59_PU_x
59_Trip_x
27_PU_x
27_Trip_x
27 Trip
27 PU
835