GE UR F35 Series Instruction Manual page 388
Multiple feeder protection
system
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- Instruction manual (526 pages) ,
- Instruction manual (596 pages) ,
- Instruction manual (616 pages)
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6.3 METERING
i) FREQUENCY METERING
PATH: ACTUAL VALUES
FREQUENCY
SRC 1
The metered frequency values are displayed in this menu. The "SRC 1" text will be replaced by whatever name was pro-
grammed by the user for the associated source (see
is measured via software-implemented zero-crossing detection of an AC signal. The signal is either a
SOURCE FREQUENCY
Clarke transformation of three-phase voltages or currents, auxiliary voltage, or ground current as per source configuration
(see the
SYSTEM SETUP
final frequency measurement is passed through a validation filter that eliminates false readings due to signal distortions and
transients.
j) VOLTAGE HARMONICS AND THD METERING
PATH: ACTUAL VALUES
VOLTAGE HARMONICS
SRC 1
The metered voltage harmonics values are displayed in this menu. The "SRC 1" text will be replaced by the programmed
name for the associated source (see the
6
To extract the 2nd to 25th voltage harmonics, each harmonic is computed on a per-phase basis, where:
N = 64 is the number of samples per cycle
ω
= 2πf is the angular frequency based on the system frequency (50 or 60 Hz)
0
k = 1, 2,..., N – 1 is the index over one cycle for the Fast Fourier Transform (FFT)
m is the last sample number for the sliding window
h = 1, 2,..., 25 is the harmonic number
The short-time Fourier transform is applied to the unfiltered signal:
The harmonics are a percentage of the fundamental signal obtained as a ratio of harmonic amplitude to fundamental ampli-
tude multiplied by 100%. The total harmonic distortion (THD) is the ratio of the total harmonic content to the fundamental:
Voltage harmonics are calculated only for Wye connected phase VTs. Ensure the
VOLTAGE BANK F5
NOTE
6-22
METERING
SOURCE SRC 1
SRC 1
FREQUENCY:
0.00 Hz
settings). The signal used for frequency estimation is low-pass filtered. The
POWER SYSTEM
METERING
SOURCE SRC 1
SRC 1
Vb:
0.0 Vc:
SRC 1
MESSAGE
Vb:
0.0 Vc:
SRC 1
MESSAGE
Vb:
0.0 Vc:
SRC 1
25TH Va:
MESSAGE
Vb:
0.0 Vc:
SETTINGS
2
F
(
m h
,
)
--- -
=
real
N
k
2
F
(
m h ,
)
--- -
=
imag
N
k
(
m h ,
)
F
F
=
ampl
THD
=
PHASE VT XX CONNECTION
F35 Multiple Feeder Protection System
FREQUENCY
SETTINGS
SYSTEM SETUP
VOLTAGE HARMONICS
THD Va:
0.0
0.0%
2ND Va:
0.0
0.0%
3RD Va:
0.0
0.0%
↓
0.0
0.0%
SYSTEM SETUP
SIGNAL SOURCES
(
f m k
(
)
⋅
cos
(
h ω
⋅
⋅
t k ( )
)
)
–
0
(
f m k
(
)
⋅
sin
(
h ω
⋅
⋅
t k ( )
)
)
–
0
2
2
(
,
)
(
,
)
m h
F
m h
+
real
imag
2
2
2
F
F
...
F
+
+
+
2
3
25
setting is "Wye" to enable voltage harmonics metering.
6 ACTUAL VALUES
).
SIGNAL SOURCES
menu).
SYSTEM SETUP
AC INPUTS
(EQ 6.3)
(EQ 6.4)
GE Multilin
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