Scaling Factors For Analogreport Channels - Hitachi Relion 670 Series Applications Manual

Section 6
Wide area measurement system
anti-aliasing filter will be automatically selected based on the reporting rate and the performance class
(P/M) settings. The filters are designed to attenuate all aliasing frequencies to at least -40 dB (a gain of
0.01) at M class.
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
6.1.3.3

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 (AnalogDataType) as Integer, there will be a down-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 -AnalogXRange and +AnalogXRange. The resulting scale factor will be applied to the
reported analog data where applicable.
If the AnalogDataType is selected as Float, then these settings are ignored.
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
82
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 2
=
65535.0
=
0.0
=
16 bit integer range
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1MRK511407-UUS Rev. N
(Equation 15)
GUID-0DDAF6A9-8643-4FDD-97CF-9E35EF40AF7E v2
Phasor measurement unit RES670
Application manual