ABB Relion 670 Series Applications Manual page 108
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Also See for Relion 670 Series:
- Technical manual (1432 pages) ,
- Technical reference manual (1232 pages) ,
- Applications manual (944 pages)
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Section 6
Wide area measurement system
For example, when the synchrophasor measurement follows the fundamental frequency
beyond the fixed Nyquist limits in C37.118 standard, the anti-aliasing filter stopband moves
with the measured fundamental frequency. This has to be considered in connection with
C37.118, where the passband is defined relative to a fixed nominal frequency as shown in the
equation 15.
F
s
f
±
0
2
IECEQUATION2418 V1 EN-US
where,
f
0
F
s
6.2.3.3
Scaling Factors for ANALOGREPORT channels
The internal calculation of analog values in the IED is based on 32 bit floating point. Therefore,
if the user selects to report the analog data (
conversion of a 32 bit floating value to a new 16 bit integer value. In such a case, in order to
optimize the resolution of the reported analog data, the user-defined analog scaling is
implemented in the IED.
The analog scaling in the IED is automatically calculated by use of the user-defined parameters
AnalogXRange for the respective analog channel X. The analog data value on the input X will
have a range between
applied to the reported analog data where applicable.
AnalogDataType is selected as Float , then these settings are ignored.
If the
The analog scaling in the IED is calculated using the equation:
S calefactor
offset
65535.0
IECEQUATION2443 V1 EN-US
According to the IEEE C37.118.2 standard, the scale factors (conversion factor) for analog
channels are defined in configuration frame 2 (CFG-2) and configuration frame 3 (CFG-3)
frames as follows:
•
CFG-2 frame: The field ANUNIT (4 bytes) specifies the conversion factor as a signed 24 bit
word for user defined scaling. Since it is a 24 bit integer, in order to support the floating
point scale factor, the scale factor itself is multiplied in 10, so that a minimum of 0.1 scale
factor can be sent over the CFG-2 frame. The resulting scale factor is rounded to the
nearest decimal value. The clients receiving the Analog scale factor over CFG-2 should
divide the received scale factor by 10 and then apply it to the corresponding analog data
value.
•
CFG-3 frame: The field ANSCALE (8 bytes) specifies the conversion factor as X' = M * X + B
where; M is magnitude scaling in 32 bit floating point (first 4 bytes) and B is the offset in
32 bit floating point (last 4 bytes).
102
The synchrophasor measurement is adaptive as it follows the fundamental
frequency over a wide range despite the reporting rate.
is the nominal frequency
is the reporting rate
-AnalogXRange and +AnalogXRange . The resulting scale factor will be
´
AnalogXRange
2
=
65535.0
=
0.0
=
16
bit integer range
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AnalogDataType ) as Integer , there will be a down-
1MRK 511 401-UEN Rev. K
(Equation 15)
GUID-0DDAF6A9-8643-4FDD-97CF-9E35EF40AF7E v2
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