Frequency error #4
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Hello Jaime, As already mentioned here: #3 (comment) So we do not expect to get there So if you can provide Please let us know if you think this is misinterpreted. If you could share with us your sample data we might have a solution for you - how to adjust the script to get correct measurements. However, there might be a bug in |
According to C37.118 standard, the most significant bit in Data format defines representation of FREQ/DFREQ. If this bit is logical "1", frequency is shown by floating point, otherwise 16-bit integer. If we have representation in 16-bit integer, than FREQ is frequency deviation from nominal in mHz. In other case it is actual frequency value ( I think in mHz too).
This reverts commit c56bc9e.
According to C37.118 standard, the most significant bit in Data format defines representation of FREQ/DFREQ. If this bit is logical "1", frequency is shown by floating point, otherwise 16-bit integer. If we have representation in 16-bit integer, than FREQ is frequency deviation from nominal in mHz. In other case it is actual frequency value.
In C37.118.2-2011 - IEEE Standard for Synchrophasor Data Transfer for Power Systems says that frequency can be 32 bit floating point in witch case we would use real value of freq and 16 intiger in witch case we would represent frequency as real value of frequency + deviation frequency
When FREQ is 16-bit integer, it is considered to be frequency deviation from nominal (in mHz) and it is added to nominal frequency value to get actual value of frequency (see one of my commits) , divided by 1000. When FREQ is floating points, it is actual frequency value that should be written in Hz (because range is -32767 <= freq<=32767, so max value would be 32.767Hz if we use mHz for input). This is only my understanding of standard and should be checked by others.
Hello, I am trying to use your Python app (pyPMU) in its pdc option. However, I have problems with reading the data from ints special format, mainly regarding the frequency. This variable is not correct. I am using PMU data in 60 Hz. In this connection, I already read the previous issue named "Trouble Reading from SEL735" and I did your suggested change in line 2144 in frame.py, after which it works. However, the frequency keeps in 60.06 Hz, almost constant (please see the attached figure).
I realized that this value was also reported on the mentioned previous issue "Trouble Reading from SEL735". Therefore, please help me with suggestions for solving this inconsistency. Thanks in advance for your help and for sharing this so interesting application.
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