Today I'm going to have a look on such possibilities like obtain data from oscillograms.
As well in that publication I leave the link where you can get working example this development.
Why on earth? It could be reasonable ask reader.
And that is why.
Just imagine, that you have thousands saved oscillograms – as result of disturbance recorders relay protection devices during the long term.
Usually in manual mode such giant oscillograms base could be useful few and far between. For example, when you know particular date (or some duration between dates) and you going to have related events. Oscillograms files you could to filter by the date – and that is all means of automation in such mode.
Most of the time such bulk just senseless plummet for your hard drive.
However, on the other point – this is the big data!
And any big data could be source of valuable information.
And even so - what could we do with oscillograms? Perhaps to try “digitalize” that. More specifically it is already done, just we need this digital data somehow extract and use that for analyzing in auto mode.
So that such giant base oscillograms process machine instead human.
Let’s sketch out several scenarios, where that could be useful for me personally:
1) Sometimes during the calculation relay protection settings, it is necessary to have real samples of starting currents of feeders. As usual this is the motor feeders. Disturbance recorders (DR) working not just during the start motors. Default it is recording when protection is pickup and trip. Frequently DR set on the CB operations. Commonly there is many other cases, where working DR not related with just starts motors, and even on the one feeder to find starting oscillograms happens not easy.
Just believe me, when there are one hundred feeders and over, then to open every oscillogram, to move rulers left-right, in search of starting current quite a piece of work.
2) You will be surprised but it could be possible reveal where current circuits wrong earthed – with 2 and more points of grounding, that as you know could lead to false trip relay protections. Such commissioning mistakes.
Did it like this.
Choosing all oscillograms, where appear current during the OFF-position CB.
Of course, it could be different cases, not always potentials difference or longitude of current circuits enough, so that double pointed earthing made current through current circuits.
However, in my case it could be succeed reveal on the several feeders exactly this case.
There were residual current transformers with long circuits, and investigation shown that it was grounded in more than 2 points (even 3 points of earthing).
3) To reveal long operation time CB for ON-OFF operations. As an alternative to see it over time – whether increase operation time?
In my case I found one CB with operation time longer than 1 sec, that is less than successful.
Here I just listed such cases which was useful for me in real life.
To find better application just depend of your own imagination.
So that realize this idea I had to scrutinize COMTRADE standard 1999, this standard almost completely coincide with 2001, which is, if I am not mistaken, was withdrawn, but successfully working on relay protection devices such as Sepam 80.
My development I tested on the pointed above oscillograms Sepam 80 devices, as well on the ABB REF620 and REF615 (this REFs used standard 99 years).
And now standard COMTRADE describe how data should be packed in binary format in files .dat of oscillograms.
Text format of data (also exist, if someone does not know) I didn’t implement, because this is not much spread, as economy memory reasons default using binary .dat format oscillograms.
Text file .cfg also using in my development, the standard using that as key for unpacking data from .dat files.
Originally, I wrote library for conversion to data from oscillograms in the clear Python, but latter, I rewrote that on the C++, that gave boost in several times.
Eventually data analysis realized on Python, where inside importing lib written and compiled on C++, which convert oscillograms to data.
Below reader can find link to GitHub, where I leave my lib and working example, which is find in the oscillograms storage all trends with starting currents and copy that to pointed place.
Description of working example and how to use lib you can find in the same place.