Green Building Forum - CHP and Demand Matching Sun, 25 Oct 2026 15:14:54 +0000 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 CHP and Demand Matching https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191150#Comment_191150 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191150#Comment_191150 Sun, 08 Dec 2013 14:12:57 +0000 billt
No doubt it would be possible to design small inverters which would load shed with very small frequency increments, but it wouldn't be worth it as their grid contribution is trivial. Solar farms are a different issue, but I'd expect then to be under central grid control like any other reasonably large generator.

Posted By: SteamyTea
I would think that a local grid will lots of micro generation on it is a pretty low quality noisy place (electrically).

Anyone know how well an inverter tracks grid frequency?


They track grid frequency perfectly. If they don't they'll go bang, or at least smoke briefly.

There's no reason why a local grid should be noisy. Good inverters have a low distortion output, and adding other inverters in a controlled fashion shouldn't add noise.]]> CHP and Demand Matching https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191151#Comment_191151 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191151#Comment_191151 Sun, 08 Dec 2013 14:22:25 +0000 SteamyTea Posted By: Ed DaviesIt depends on the imbalance between generation and demand. , Yes, that is what I meant.

Posted By: billtbut it wouldn't be worth it as their grid contribution is trivial.
Any idea when it does become a problem?]]> CHP and Demand Matching https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191153#Comment_191153 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191153#Comment_191153 Sun, 08 Dec 2013 14:55:26 +0000 renewablejohn
This explains better than me

http://www.vde.com/en/fnn/pages/50-2-hz.aspx]]> CHP and Demand Matching https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191154#Comment_191154 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191154#Comment_191154 Sun, 08 Dec 2013 15:03:24 +0000 Ed Davies
Yes, there are those off-grid systems. However, RJ is right that in Germany they now have a system where grid-tied PV inverters back off their output in response to grid frequency as has just been described here:

http://www.navitron.org.uk/forum/index.php/topic,21536.msg249026.html#msg249026

Searching around a bit I _think_ that all new systems are supposed to do this but only old systems over 10 kW needed to be retrofitted to do it or to cut off at various frequencies around 50.2 Hz (so they don't all go off together).

There's also the, perhaps more worrying, concern with lots of G83 generation that they'll all drop off at the same low frequency which is already indicating that the grid is in poor shape (demand exceeding immediately available generation) with the possible consequence of a cascading failure (as GavinA reminds us earlier in that Navitron thread).]]> CHP and Demand Matching https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191221#Comment_191221 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11494&Focus=191221#Comment_191221 Mon, 09 Dec 2013 18:21:24 +0000 markocosic
Voltage is a LOCAL thing related to impedance of the network and the load on it. The network was designed as a one way device as has previously been described. Asking it to transmit power in two directions can be problematic, and exhibits itself as a voltage that dips too low under load (winter) and rises too high under local generation (summer). Inverters can't fix this; you need to upgrade the local distribution infrastructure not just the inverter.

G83 written with a random element to the exact disconnect time/frequency would have been wise in hindsight.]]>