GE D30 Instruction Manual page 26

SIGNAL PROCESSING
Analog Inputs
U
From
2
CT/VT
I
DSP module
HMI
Ethernet
ports
Communi-
Serial
cation
ports protocols
IRIG-B
Accurate
IEEE
Real-Time
1588
clock
SNTP
CPU module
The UR samples its AC signals at 64 samples per cycle, that is, at 3840 Hz in 60 Hz systems, and 3200 Hz in 50 Hz systems.
The sampling rate is dynamically adjusted to the actual system frequency by an accurate and fast frequency tracking
system.
The A/D converter has the following ranges of AC signals:
Voltages:
Currents:
Current harmonics are estimated based on raw samples with the use of the full-cycle Fourier filter. Harmonics 2nd through
25th are estimated.
True RMS value for the current is calculated on a per-phase basis. The true RMS can be used for demand recording or as an
input signal to Time Overcurrent function, if the latter is intended for thermal protection. The true RMS is calculated as per
the widely accepted definition:
2-16
Figure 2-3: UR signal processing
Analog-to-
Analog low-
Digital
pass filter
Converter
A
D
Synchro-
phasors
Sampling
filtering
frequency
Tracking
frequency
selection,
estimation
Time stamping
Channel
Ddebounce
monitoring
filtering
CRC check
G.703, RS-422,
Optoisolated
C37.94, direct fiber
I
RMS t ( )
Phasor
Digital band-
estimation
pass filter
½ cycle
Fourier
1 cycle
Fourier
T
Protection
algorithms
I>
elements,
Z< monitoring
elements,
U<
FlexLogic,
Synchrophasors
Aggregation,
calculations
post-filtering
A
D
DCmA, RTD
± 2 ⋅ 260 V ( )
± 2 ⋅ 46rated A ( )
t
1
2

= -- i t ( ) t d
T
( t T )
–
D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 2: PRODUCT DESCRIPTION
Fundamen
tal freq.
Phasors,
Seq. com-
ponents
Frequency
RMS
values
Analog Outputs
module
Events
Control
Comtrade, data
logger
DNP, Modbus,
IEC60870
PMU (IEEE C37.118,
IEC 61850-90-5)
IEC 61850 (GOOSE,
MMS Server)
Inter-relay
comms
module
Contact Outputs
module
859740A1.vsd
Eq. 2-1
Eq. 2-2
Eq. 2-3