Voltage Harmonic Monitoring Vhmmhai(Vthd); Function Revision History; Identification; Application - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
16.11

Voltage harmonic monitoring VHMMHAI(VTHD)

16.11.1

Function revision history

Document
revision
D
E
F
G
H
J
K
M
N
16.11.2

Identification

Function description
Voltage harmonic monitoring
16.11.3

Application

In order to maintain the power quality for better supply, harmonics in the system must be monitored. Due
to the nonlinear loads connected to the system, harmonics (apart from fundamental frequency
component) are generated and thereby the system voltage is distorted. Voltage distortion appears to
have a little effect on operation of nonlinear loads connected, either phase-to-phase or phase-to-neutral.
Current distortion is limited at the point of common coupling PCC to control the harmonic current from the
utility to the consumer. Thereby, the voltage distortion must be limited in order to prevent it from
spreading to other facilities.
Voltage harmonic distortion levels can vary drastically, depending on the configuration of system. These
voltage harmonics can damage the equipment as they are designed to operate for certain range of
voltage inaccuracy.
Moreover, in four-wire distribution systems (three-phase and neutral), the currents in the three phases
will return via the neutral conductor, a 120 degree phase shift between corresponding phase currents that
causes the currents to cancel out in the neutral, under balanced loading conditions. When nonlinear
loads are present, any 'Triplen' (3
However, they will be added cumulatively in the neutral conductor, which can carry up to 173% of phase
current at a frequency of predominately 180 Hz (3
In general, harmonics can cause reduced equipment life if a system is designed without considering the
harmonics and if the equipment is not designed to withstand harmonics. Hence, it is important to
measure and monitor harmonics in power systems. Harmonic voltage distortions on 161 kV power
Phasor measurement unit RES670
Application manual
Product History
revision
2.2.3 -
2.2.3 -
2.2.3 -
2.2.4 -
2.2.4 -
2.2.4 -
2.2.5
Updated monitoring till 9
th
monitoring till 5
2.2.6 -
2.2.6 -
IEC 61850
identification
VHMMHAI
rd th
, 6 , and 9
© 2017 - 2023 Hitachi Energy. All rights reserved
th
order voltage harmonics. Refer to document revision J for
order voltage harmonics.
IEC 60617
identification
UTHD
th
) harmonics in the phase currents does not cancel out.
rd
harmonic).
GUID-B2F24353-AAEA-4520-BB1C-5FD5FFCFC67B v1
GUID-E828F930-88FF-4D5B-8304-2BD3B89919B8 v2
GUID-BF90E93F-C0F4-43F7-BDD5-F3C289B5535B v1
ANSI/IEEE C37.2
device number
VTHD
GUID-987BCB6C-C559-42EE-9AAB-5F71189A58C6 v3
GUID-45A6724C-1FF0-4910-9878-01518111EB26 v1
Section 16
Monitoring
259