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TOPIC: Messure average windspeed over a year

Messure average windspeed over a year 1 year 1 month ago #1

  • 2paul
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Hardware:
RaspberryPi Zero
PiLogger
Eltako Windsensor WS

I am really happy with your Software/Hardware, you did a really good job, only thing whats missing is, that whats already here in the forum, the possibility to deactivate messure types, for making the logsize smaller.

I used the webmontor options from here, because they used same windsensor.
www.pilogger.de/index.php/en/forum/proje...onfigurieren?start=6

My goal is, to messure the average windspeed over a year, to know, if it is worth to install a real windwheel for generate electic energy.

I have still 2 questions:
1. Can I rise up the logfactor to 7200, to log only every hour ? Will that still give corrects results ?
2. The sensor give 2 signals per one rotation, I used the Factor Pulse from 0.4, is this correct ? Its hard for me to controll my results, the wind permanenty changes, but i need more or less correct values, to see if its worth to a big windwheel.

I attach just some picture from my testenviroment

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Last Edit: by 2paul.

Messure average windspeed over a year 1 year 1 month ago #2

  • PiLo-Heinz
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Hi Paul,
thanks for your compliments - i'll forward it!
Regarding your questions:
- all i found about the eltako wind sensor is giving a sensor constant of 0.34 instead of 0.4 .
For a wind speed of 115,2 km/h (32 m/s), which is stated as maximum (??), a pulse rate of 94 per second is expected.
So just change this value in WebMonitor :cheer:
- with this value the counting range of the PiLogger would overflow after 704 seconds (constant wind speed of 32 m/s as worst case).
So the wind measuring time should be kept below app. 12 minutes.
If you like to have a faster measurement of temperature and/or voltage/current/power then you could use the 'Pulszähl Zeitfaktor' to achieve different measuring intervals. For instance main interval at 10 sec with factor 72 is resulting in a wind speed measurement time of 12 minutes.
On top of this the logging interval will compact the data which are actually written to the log file. All subsequent preformed measurements are averaged for the log interval.
So if you for instance choose a log interval of 10 minutes, the diagrams as the csv file will give a data point only every 10 minutes.
This it is not really necessary to save storage space ! The SD card will have huge space for a lot of data.
At the bottom of the page 'Einstellungen 2' there is a calculation of the size and overall time interval per csv file generated.
File sizes of 1 - 2 Mbytes shall be not a problem.
In general you can download the csv file for each period at any time and just treat it with a spreadsheet application.
The only trick is to take into account that the english app is expecting a dot for float numbers where the german version expects a comma !
So you can combine many time period files to one big file to perform calculation on years :lol: - also for example filtering and comparing days and nights ... and so on.
For the feature request 'rolling diagram' from the cited thread : yes , i think it would be a nice feature. I've not yet got a time schedule for this, just the statement : 'should be possible'.

btw : i can't see your photo attachment. Did you use a restricted link ?

Hope this helps you to go on !
Greetings,
PiLo-Heinz

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Nichts ist unmöglich :-)
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Messure average windspeed over a year 1 year 1 month ago #3

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Woow, thank you very much, for this support und the detailed answer...
I also searched for more information about the sensor, the official datasheet is very limited...

I found here some answers:
www.amazon.de/Eltako-Windsensor-WS/produ...reviews&pageNumber=3

The official Calculation is:
Windspeed [m/s] = (Impulse per second + 2) / 3

But there some other formulas as well, based on test
m/s = (imp/s + 4.5) / (6 - (imp/s / 60))
or
v [km/h] = 1.761 / (1 + rps) + 3.013 * rps

So I think your Factor Pulse 0.34 comes very close to the official Calculation, otherwise i have to go in the python code, right ?

Of course, there is no problem to produce more logdata, and use shorter logtimes, and of course could be intressting to see, how the wind change in day- and nighttimes. Because I want that windenergy mostly in addition to my solarenergy, mostly to save battery-capacity in nighttimes.
And of course i will make backups on bigger maschines, where logdata-sizes makes no problem

The problem with the pictures was, that the forum always said, i have to much links in my post, so i have to remove all the pics, but i will try again in a new post ...

Thx again, continue your good work.
paul
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Messure average windspeed over a year 1 year 1 month ago #4

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Picture test


didnt work, when i insert 3 pics, the forum says: "To many links"
Then i removed one, and send, but its still not showing them... :(

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Messure average windspeed over a year 1 year 1 month ago #5

  • PiLo-Heinz
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Hi Paul,

thanks for your feedback !
I just raised the limits for attachments... and attached one document i was refering to.
Maybe your pictures were bigger than 1 MB ?
Now i set it to 2 MB - please scale them down to 800px width before uploading.
I didn't do that on the last topic and now these pictures are shown way too big ...:(

Thank you !
PiLo-Heinz
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Nichts ist unmöglich :-)
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Messure average windspeed over a year 1 year 1 month ago #6

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Thanks, for the changes... i forgot that, was sooo long not active in any forum :)

And thanks for the datatable from Eltako.
But thats mean that have to change the code to calculate right, right ??
This formular works for the datatable from Eltako.
Windspeed [m/s] = (Impulse per second + 2) / 3

But when i use just 0.34 as factor, i get complete different values, in lower area even more, average windspeed will here below 6m/s.



Still no pictures ?? und this time they had about 100kB.

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