ABB Relion 670 Series Applications Manual page 274

Section 16
Monitoring
WrnLimitTDD : It defines the warning limit for the calculated total demand distortion. Harmonic
current distortions on a power systems with ratio between the maximum short circuit current to
the maximum demand load current is 20, limited to 5% of the total demand distortion (TDD).
tDelayAlmTDD : It defines the alarm delay time from warning for the calculated total demand
distortion.
WrnLimitTHD : It defines the warning limit for the calculated total harmonic distortion.
tDelayAlmTHD : It defines the alarm delay time from warning for the calculated total harmonic
distortion. This intimates the operator to take corrective operations immediately, otherwise the
system will undergo thermal stress.
WrnLimit2ndHD : It defines the warning limit for the calculated second harmonic distortion.
tDelayAlm2ndHD : It defines the alarm delay time from warning for the calculated second harmonic
distortion.
WrnLimit3rdHD : It defines the warning limit for the calculated third harmonic distortion.
tDelayAlm3rdHD : It defines the alarm delay time from warning for the calculated third harmonic
distortion.
WrnLimit4thHD : It defines the warning limit for the calculated fourth harmonic distortion.
tDelayAlm4thHD : It defines the alarm delay time from warning for the calculated fourth harmonic
distortion.
WrnLimit5thHD : It defines the warning limit for the calculated fifth harmonic distortion.
tDelayAlm5thHD : It defines the alarm delay time from warning for the calculated fifth harmonic
distortion.
16.11 Voltage harmonic monitoring VHMMHAI(VTHD)
16.11.1 Identification
Function description
Voltage harmonic monitoring
16.11.2 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.
268
IEC 61850
identification
VHMMHAI
© Copyright 2017 Hitachi Power Grids. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
UTHD VTHD
Phasor measurement unit RES670
1MRK 511 407-UUS Rev. J
GUID-B2F24353-AAEA-4520-BB1C-5FD5FFCFC67B v1
GUID-BF90E93F-C0F4-43F7-BDD5-F3C289B5535B v1
GUID-987BCB6C-C559-42EE-9AAB-5F71189A58C6 v2
Application manual