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Is that kind of load variation from large data centers really a problem to the power grid? There are much worse intermittent loads, such as an electric furnace

Is that kind of load variation from large data centers really a problem to the power grid? There are much worse intermittent loads, such as an electric furnace or a rolling mill.

paulkrush 2y ago
Edit: It's interesting the GPU's are causing issues on the grid before they cause issues with the data center's power.
- mystified5016 2y ago
  Read the article.
toast0 2y ago
I suspect it's more of a problem for the data center's energy bill. My understanding is that large electric customers pay a demand charge in addition to the volumetric charge for the kWh's use at whatever rates given time of use / wholesale rates. The demand charge is based on the maximum kW used (or sometimes just the connection size) and may also have a penalty rate if the power factor is poor. Smoothing over small duration surges probably makes a lot of things nicer for the rate payer, including helping manage fluctuations from the utility. There's probably something that could be done on the individual systems so that they don't modulate power use quite so fast, too; at some latency cost, of course. If you go all the way to the extremes, you might add a zero crossing detector and use it to time clock speed increases.
- deleted 2y ago
  [deleted]
- timewizard 2y ago
  If you have a working thermometer you can predict when furnaces are going to run. If you want to smooth out data centers then you need hourly pricing to force them to manage their demand into periods where excess grid capacity is not being used to serve residential loads.
- hinkley 2y ago
  Large customers pay not by wattage but by… I’m spacing on the word but essentially how much their power draw fucks up the sine waves for voltage and current in the power grid. I imagine common power rail systems in hyperscaler equipment helps a bit with this, but for sure switching PSUS chop up the input voltage and smooth it out. And that leads to very strange power draws.
  - murderfs 2y ago
    You're probably thinking of power factor, which is usually not a big deal for datacenters. All of your power supplies are going to have active PFC, and anything behind a double conversion UPS is going to get PFC from the UPS. The biggest contributors are probably going to be the fans in the air conditioning units.
    - Animats 2y ago
      This isn't about power factor. That's a current vs. voltage thing within one cycle. It's about demand side ramp rate - how fast load can go up and down. Ramp rate has been a generation side thing for a century. Every morning, load increases from the pre-dawn low, and which generators can ramp up output at what speed matters. Ramp rate is usually measured in megawatts/minute. Big thermal plants, atomic and coal, have the lowest ramp rates, a few percent per minute. Ramp rate demand side, though, is a new thing. There are discussions about it [1] but it's not currently something that's a parameter in electric energy bills. [1] https://www.aceee.org/files/proceedings/2012/data/papers/0193-000178.pdf https://www.aceee.org/files/proceedings/2012/data/papers/019...
      - hinkley 2y ago
        For factories it’s both, but if by “this” you mean the article, I agree. Bursty traffic is the problem they’re most trying to solve. It’s akin (but other side of the coin) to when NAS hardware learned to stagger drive spool up during power on to avoid brownouts. Startup current on spinning platters is ridiculous. You have to do something to buffer, and you can do it on the supply or demand side. Or for large problems, both.
- oakwhiz 2y ago
  There is often a demand flux surcharge as well. Not just demand but delta in demand over some time period.
changoplatanero 2y ago
Yes its a problem for the grid and the power companies don't allow large clusters to oscillate their power like this. The solution that AI have to do during their training big runs is to fill in the idle time on the GPUs with dummy operations to keep the power load constant. Having capacitors would be able to save on power usage.
- nancyminusone 2y ago
  Inb4 a startup is created to sell power load idle cycle compute time in AI training data centers.
mystified5016 2y ago
Those loads aren't nearly as intermittent. Your furnace likely runs for tens of minutes at a time. These datacenters are looking at second-to-second loads. Drawing high intermittent loads at high frequency likely makes the utility upset and leads to over-building supply to the customer to cope with peak load. If you can shave down those peaks, you can use a smaller(cheaper) supply connection. A smoother load will also make the utility happy. Remember that electricity generation cannot ramp up and down quickly. Big transient loads can cause a lot of problems through the whole network.

Is that kind of load variation from large data centers really a problem to the power grid? There are much worse intermittent loads, such as an electric furnace or a rolling mill.

paulkrush 2y ago

Edit: It's interesting the GPU's are causing issues on the grid before they cause issues with the data center's power.

mystified5016 2y ago
Read the article.

toast0 2y ago

I suspect it's more of a problem for the data center's energy bill. My understanding is that large electric customers pay a demand charge in addition to the volumetric charge for the kWh's use at whatever rates given time of use / wholesale rates. The demand charge is based on the maximum kW used (or sometimes just the connection size) and may also have a penalty rate if the power factor is poor. Smoothing over small duration surges probably makes a lot of things nicer for the rate payer, including helping manage fluctuations from the utility. There's probably something that could be done on the individual systems so that they don't modulate power use quite so fast, too; at some latency cost, of course. If you go all the way to the extremes, you might add a zero crossing detector and use it to time clock speed increases.

deleted 2y ago
[deleted]
timewizard 2y ago
If you have a working thermometer you can predict when furnaces are going to run. If you want to smooth out data centers then you need hourly pricing to force them to manage their demand into periods where excess grid capacity is not being used to serve residential loads.
hinkley 2y ago
Large customers pay not by wattage but by… I’m spacing on the word but essentially how much their power draw fucks up the sine waves for voltage and current in the power grid. I imagine common power rail systems in hyperscaler equipment helps a bit with this, but for sure switching PSUS chop up the input voltage and smooth it out. And that leads to very strange power draws.
- murderfs 2y ago
  You're probably thinking of power factor, which is usually not a big deal for datacenters. All of your power supplies are going to have active PFC, and anything behind a double conversion UPS is going to get PFC from the UPS. The biggest contributors are probably going to be the fans in the air conditioning units.
  - Animats 2y ago
    This isn't about power factor. That's a current vs. voltage thing within one cycle. It's about demand side ramp rate - how fast load can go up and down. Ramp rate has been a generation side thing for a century. Every morning, load increases from the pre-dawn low, and which generators can ramp up output at what speed matters. Ramp rate is usually measured in megawatts/minute. Big thermal plants, atomic and coal, have the lowest ramp rates, a few percent per minute. Ramp rate demand side, though, is a new thing. There are discussions about it [1] but it's not currently something that's a parameter in electric energy bills. [1] https://www.aceee.org/files/proceedings/2012/data/papers/0193-000178.pdf https://www.aceee.org/files/proceedings/2012/data/papers/019...
    - hinkley 2y ago
      For factories it’s both, but if by “this” you mean the article, I agree. Bursty traffic is the problem they’re most trying to solve. It’s akin (but other side of the coin) to when NAS hardware learned to stagger drive spool up during power on to avoid brownouts. Startup current on spinning platters is ridiculous. You have to do something to buffer, and you can do it on the supply or demand side. Or for large problems, both.
oakwhiz 2y ago
There is often a demand flux surcharge as well. Not just demand but delta in demand over some time period.

changoplatanero 2y ago

Yes its a problem for the grid and the power companies don't allow large clusters to oscillate their power like this. The solution that AI have to do during their training big runs is to fill in the idle time on the GPUs with dummy operations to keep the power load constant. Having capacitors would be able to save on power usage.

nancyminusone 2y ago
Inb4 a startup is created to sell power load idle cycle compute time in AI training data centers.

mystified5016 2y ago

Those loads aren't nearly as intermittent. Your furnace likely runs for tens of minutes at a time. These datacenters are looking at second-to-second loads. Drawing high intermittent loads at high frequency likely makes the utility upset and leads to over-building supply to the customer to cope with peak load. If you can shave down those peaks, you can use a smaller(cheaper) supply connection. A smoother load will also make the utility happy. Remember that electricity generation cannot ramp up and down quickly. Big transient loads can cause a lot of problems through the whole network.