ABB RELION 620 Series Technical Manual page 702

Section 8
Power quality measurement functions
8.4
8.4.1
8.4.2
8.4.3
696
Voltage unbalance PQVUB
Identification
Function description
Voltage unbalance
Function block
PQVUB
V_A MN_UNB_AL
PCT_UNB_AL
V_B
V_C OBS_PR_ACT
V
1
V
2
V
0
BLOCK
GUID-5248E9E7-BE34-4B9E-B402-611B2557E536 V2 EN
Figure 351: Function block
Functionality
The voltage unbalance power quality function PQVUB monitors voltage unbalance
conditions in power transmission and distribution networks. It can be applied to identify
a network and load unbalance that can cause sustained voltage unbalance. PQVUB is also
used to monitor the commitment of the power supply utility of providing a high-quality,
that is, a balanced voltage supply on a continuous basis.
PQVUB uses five different methods for calculating voltage unbalance. The methods are
the negative-sequence voltage magnitude, zero-sequence voltage magnitude, ratio of the
negative-sequence voltage magnitude to the positive-sequence voltage magnitude, ratio
of the zero-sequence voltage magnitude to the positive-sequence voltage magnitude or
ratio of maximum phase voltage magnitude deviation from the mean voltage magnitude
to the mean of the phase voltage magnitude.
PQVUB provides statistics which can be used to verify the compliance of the power
quality with the European standard EN 50160 (2000). The statistics over selected period
include freely selectable percentile for unbalance. PQVUB also includes an alarm
functionality providing a maximum unbalance value and the date and time of occurrence.
PQVUB contains a blocking functionality. It is possible to block function outputs, if
desired.
IEC 61850 IEC 60617
identification identification
VSQVUB PQMUBU
1MAC504801-IB E
ANSI/IEEE C37.2
device number
PQVUB
620 series ANSI
Technical Manual