6-22
F35 Multiple Feeder Protection System
GE Multilin
6.3 METERING
6 ACTUAL VALUES
6
i) FREQUENCY METERING
PATH: ACTUAL VALUES
METERING
SOURCE SRC 1
FREQUENCY
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
SETTINGS
SYSTEM SETUP
SIGNAL SOURCES
).
SOURCE FREQUENCY
is measured via software-implemented zero-crossing detection of an AC signal. The signal is either a
Clarke transformation of three-phase voltages or currents, auxiliary voltage, or ground current as per source configuration
(see the
SYSTEM SETUP
POWER SYSTEM
settings). The signal used for frequency estimation is low-pass filtered. The
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
METERING
SOURCE SRC 1
VOLTAGE HARMONICS
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
SETTINGS
SYSTEM SETUP
SIGNAL SOURCES
menu).
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
0
= 2
π
f
is the angular frequency based on the system frequency (50 or 60 Hz)
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:
(EQ 6.3)
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:
(EQ 6.4)
Voltage harmonics are calculated only for Wye connected phase VTs. Ensure the
SYSTEM SETUP
AC INPUTS
VOLTAGE BANK F5
PHASE VT XX CONNECTION
setting is “Wye” to enable voltage harmonics metering.
FREQUENCY
SRC 1
SRC 1 FREQUENCY:
0.00 Hz
VOLTAGE HARMONICS
SRC 1
SRC 1
THD Va: 0.0
Vb: 0.0
Vc: 0.0%
MESSAGE
SRC 1
2ND Va: 0.0
Vb: 0.0
Vc: 0.0%
MESSAGE
SRC 1
3RD Va: 0.0
Vb: 0.0
Vc: 0.0%
↓
MESSAGE
SRC 1 25TH Va: 0.0
Vb: 0.0
Vc: 0.0%
F
real
m h
,
(
)
2
N
----
f m k
–
(
)
h
ω
0
t k
( )
⋅
⋅
(
)
cos
⋅
(
)
k
=
F
imag
m h
,
(
)
2
N
----
f m k
–
(
)
h
ω
0
t k
( )
⋅
⋅
(
)
sin
⋅
(
)
k
=
F
ampl
m h
,
(
)
F
real
m h
,
(
)
2
F
imag
m h
,
(
)
2
+
=
THD
F
2
2
F
3
2
…
F
25
2
+
+
+
=
NOTE
Summary of Contents for UR F35 Series
Page 10: ...x F35 Multiple Feeder Protection System GE Multilin TABLE OF CONTENTS ...
Page 366: ...5 238 F35 Multiple Feeder Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 426: ...10 12 F35 Multiple Feeder Protection System GE Multilin 10 6 DISPOSAL 10 MAINTENANCE 10 ...
Page 454: ...A 28 F35 Multiple Feeder Protection System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 620: ...F 12 F35 Multiple Feeder Protection System GE Multilin F 2 DNP POINT LISTS APPENDIX F F ...
Page 630: ...H 8 F35 Multiple Feeder Protection System GE Multilin H 3 WARRANTY APPENDIX H H ...
Page 640: ...x F35 Multiple Feeder Protection System GE Multilin INDEX ...