Hi All,
I have a question regarding calculating the powerusage in a household. I currently have 4 feeds that I use for calculating the power usage from. 2 of those feeds are from the PV systems, and the other 2 are current power import and export. My calculation is as follows:
pv_1 + pv_2 + power_in - power_out = power_usage
What does happen with this setup, is that the usage jumps all over the place on a day with clouds and sun. It seems that the feed updates do not happen all at the same time, so the pv_1 and pv_2 feed can be of an extreme higher value that when the last update of one of the other feeds did happen. I have all the feeds updating every 10 seconds.
Example of the calculation outcome, where power_usage should be a value of around 260 but now is not.
| PV_1 | PV_2 | POWER_IN | POWER_OUT | POWER_USAGE |
|---|---|---|---|---|
| 56 | 58 | 150 | 0 | 264 |
| 420 | 438 | 150 | 0 | 1008 |
| 265 | 230 | 0 | 744 | -249 |
| 112 | 150 | 0 | 0 | 262 |
| 496 | 480 | 0 | 0 | 976 |
| 487 | 480 | 0 | 716 | 260 |
| 112 | 120 | 100 | 0 | 332 |
| 450 | 450 | 100 | 0 | 1000 |
| 486 | 478 | 0 | 740 |
224 |
What happens here is that the feed values are not updating all at the same time, so the outcome is not as expected. Is there a trick to make the calculation more robust?
Re: Chronology feed calculations
No one around with similar issues?
Re: Chronology feed calculations
jonrescca, are all the readings coming from the same emontx?
Re: Chronology feed calculations
This had crossed my mind too... (but not seen it)
Re: Chronology feed calculations
No, the feeds have indeed a different origin, I understood that this is the origin of the problem.
I have 3 different sources supplying inputs. Those sources have a update frequenty of 10 seconds. Now that I think about it I need to rewrite my shellscripts that get the data from the sources into 1 script that updates emoncms to provide data using bulk mode. That should solve the sync issue.
Re: Chronology feed calculations
Bulk upload isn't essential and can actually pass different times for each array ( if set as such) it maybe beneficial to combine your scripts and use 1 node id , you could send one array every 10 secs, this ensures all the values will have the same time stamp and the emoncms input processing will also be uniform as the one node updates.
Paul