Smart grids

[Pierre-Yves]

Hello
There are lots of pages on smart grids, but these are always big generalities.

A friend of mine just asked me a concrete problem:
Production: 8 kW GE and possibly batteries (less than 5 kWh, not yet connected)
Consumption in 230 vac:
- Radiators 6x750 W = 4500 W (nobody is perfect ...)
- Dishwasher = 5500 W
- Service charger = 1920 W
- Coffee maker = 1640 W
- Freezer = 299 W
- Fridge = 334 W
or 15 kW knowing that everything does not work at the same time: a small "smart grid" type algorithm could very well do the trick.

It is clear, in fact, that by playing with load shedding we can manage to satisfy all consumers without blowing up the installation!

Who has an idea on the algorithm to use? It's an optimization algorithm, but I haven't thought about it much yet. If this algo is simple, we could, at least on paper, stick our tongue out at EDF !!

PY

[dirk pitt]

If this algo is simple, we could, at least on paper, stick our tongue out at EDF !!

PY

who really wants to make electricity with a generator at home?
islanding has no reason to be unless you are in an isolated site.

[Pierre-Yves]

who really wants to make electricity with a generator at home?
islanding has no reason to be unless you are in an isolated site.

I do not know what is happening, it seems to me that I had already sent a response. I start again !

Totally agree with Dirk Pitt: a GE stinks, it pollutes, it makes noise! Now, you don't have to be in an isolated site to need the "smart grids" on the one hand, and you can replace your GE with a wind turbine or PV panels on the other.

In my example, we "see" very clearly that it suffices to modulate the demand to satisfy consumption without causing a peak. However, peaks in consumption force the network to be oversized, to call on "not very clean" energies and, ultimately, contribute to overconsumption.

I have not had a lot of time to address the problem, but it interests me more and more. I think, in addition, that the optimization algorithms are not monstrous ...

So if someone has an idea, starting from my little simple example, I'm interested!

PY

[Did67]

The difficulty: on an "island", the demand is random; "consumers" do not communicate with each other; it's not "oh neighbor, I need to make myself a coffee; you postpone your laundry?" ...

ERDF does not permanently manage this request on a statistical basis: weather + habits + economic activity ...

Now, in fact, we could do much better if we had more incentives:

- part of the peak consumption is different (modern freezers can be satisfied with recharging in the middle of the night, at the lowest point; washing machine and dishwasher are different; you can switch off an inertial heating, etc. ...)

- and we could encourage to postpone certain different consumption depending on the production when it is not (dams on the water, wind, photovoltaic)

- similarly we could encourage the production of certain energies according to demand (reservoir dams, cogeneration and biogas) ...

- but that would be politics; EdF is trying to make money; not to save money !!! [even if their ads say otherwise; but they’re just pubs!]

We are already starting to charge peak electricity (in very cold weather) at its fair value and we would be making huge savings!

[Stephen]

Consumption in 230 vac:
- Radiators 6x750 W = 4500 W (nobody is perfect ...)
- Dishwasher = 5500 W
- Service charger = 1920 W
- Coffee maker = 1640 W
- Freezer = 299 W
- Fridge = 334 W

Good evening PY,

There, frankly, at the risk of appearing stupid, I do not understand these data ... or rather their values ​​and units of measurement. On the fridge, freezer, dishwasher, it doesn't sound like W but Wh. But then on the heating or the coffee maker, and the rest ???
In addition, rotate a GE or PV, + storage, (or even EDF !!) to make heat ... too stupid!
On GE, you can recover the heat from the cooling circuit (about as much calorific power dissipated by the circuit as the mechanical power actually used).

[moinsdewatt]

Consumption in 230 vac:
- Radiators 6x750 W = 4500 W (nobody is perfect ...)
- Dishwasher = 5500 W
- Service charger = 1920 W
- Coffee maker = 1640 W
- Freezer = 299 W
- Fridge = 334 W

Good evening PY,

There, frankly, at the risk of appearing stupid, I do not understand these data ... or rather their values ​​and units of measurement. On the fridge, freezer, dishwasher, it doesn't sound like W but Wh. But then on the heating or the coffee maker, and the rest ???
).

They are indeed powers, and that is expressed in W (Watt). Everything is normal.

For the dishwasher it seems a little high anyway. I don't really know, I'm doing the dishes ..... by hand.

[Pierre-Yves]

I confirm what lessdewatts says. It is indeed power, in W. Consumption is an energy and is expressed in Wh. To answer Stefano, this is not nonsense but a common mistake.

Also agree that using electricity, often produced with heat, to make heat is nonsense from the point of view of efficiency (and also from the point of view of other principles, but let's move on. ..).

That said, there is a real problem that I have not yet managed to model: how to distribute a fluctuating need to satisfy all the applicants, when we cannot satisfy everyone at the same time?

Intuitively, there is a solution. From a practical point of view, I can also find a solution "by hand", but for the moment it will not be automatic nor optimal! This is what I'm trying to find, without having yet had the time to devote a lot of time to it !!

Pierre-Yves

[Stephen]

Thanks for the reply, PY, but what I wrote is not "common error". Let me explain: I am amazed at the power of the fridge and that of the freezer. This weekend, still readings made on a fridge and a freezer gave me respectively 55 and 60 W of power and about 800 Wh / d of combined consumption for the two devices. You will therefore understand my astonishment, and especially the fact that I was wondering if it was not rather an energy consumption (therefore in Wh) over 24 hours which seemed much more plausible as a size…

But then ... what is it that these fridges and freezes? The cold rooms of a butcher ?! As for 5500 W for a dishwasher that plugs into a 16 A outlet ... Or is it a restaurant?

[Ahmed]

Did67, you write:

We are already starting to charge peak electricity (in very cold weather) at its fair value and we would be making huge savings!

Yes, the nominal cost of additional KW during these periods is very high, but, as you know, results from the thermodynamic absurdity of the choice of electric heating; the good plan would be to reduce the importance of these peaks rather than having them subsidized by the user without changing anything.

[Pierre-Yves]

Thanks for the reply, PY, but what I wrote is not "common error". Let me explain: I am amazed at the power of the fridge and that of the freezer. This weekend, still readings made on a fridge and a freezer gave me respectively 55 and 60 W of power and about 800 Wh / d of combined consumption for the two devices. You will therefore understand my astonishment, and especially the fact that I was wondering if it was not rather an energy consumption (therefore in Wh) over 24 hours which seemed much more plausible as a size…

I admit that, when I received this example, I did not try for a second to check the plausibility of the figures !! I summed the instantaneous powers (in W) and I saw that the problem was impossible if we did not distribute the requests over time and if therefore we did not switch to Wh. 5000 W for 5 minutes, it consumes 416,7 Wh, if we stop the heating for 5 minutes, it will not change the face of the world but we can do something else during this time.