Operation Principle - ABB RELION REX640 Technical Manual

1MRS759142 C
10.4.5
REX640
Technical Manual
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings. For
troubleshooting, check the contents of this chapter and also the preprocessing blocks
in this document. The configuration can be written to the protection relay once the
mismatch is corrected.

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "on" and "off".
The operation of VSQVUB can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
U_A
U_B
U_C
U3P
U
1
U
2
U
0
BLOCK
GUID-E5D7CF79-A351-4192-8BAB-312DB7153C61 V1 EN
Figure 847: Functional module diagram
Average calculation
VSQVUB calculates two sets of measured voltage unbalance values, a three-second
and a ten-minute non-sliding average value. The three-second average value is used
for continuous monitoring. The ten-minute average is used for percentile calculation
for a longer period.
The Average calculation module uses five different methods for the average
calculation. The required method can be selected with the Unb detection method
parameter.
When the "Neg Seq" mode is selected with Unb detection method, the voltage
unbalance is calculated based on the negative-sequence voltage magnitude. Similarly,
when the "Zero Seq" mode is selected, the voltage unbalance is calculated based on
the zero-sequence voltage magnitude. When the "Neg to Pos Seq" mode is selected,
the voltage unbalance is calculated based on the ratio of the negative-sequence voltage
magnitude to the positive-sequence magnitude. When the "Zero to Pos Seq" mode is
selected, the voltage unbalance is calculated based on the ratio of the zero-sequence
voltage magnitude to the positive-sequence magnitude. When the "Ph vectors Comp"
mode is selected, the ratio of the maximum phase voltage magnitude deviation from
the mean voltage magnitude to the mean of the phase voltage magnitude is used for
voltage unbalance calculation.
Power quality measurement functions
Percentile
calculation
Average
calculation
Voltage
unbalance
detector
Section 10
PCT_UNB_AL
OBS_PR_ACT
MN_UNB_AL
Recorded
data
1643