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It seems all of my home's ACDC conversion (for LED lighting, dishwasher, computers, televisions, etc) has no "Power Factor Correction" and therefore only draws power at the peaks of the 120V AC waveform (through standard full bridge rectifiers to charge a capacitor). I believe the IEC/FCC only permits this for individual circuits below 75W, but these circuits easily add up.

During cold or hot weather, I know HVAC/motor power overcomes this ACDC power, so maybe this is not a big deal for the utility company, but I still feel a bit guilty. Can a typical USA utility company, which plans for max capability of say 3kW per home, compensate fine if everyone on my grid suddenly consumed 0.5kW ACDC with no PFC starting tomorrow?

Do any cities/localities in the world have a separate distribution system (like a pure DC line) to help with this? Though I see distributed solar power as being useful here, I am wondering instead about how to distribute centralized power to thousands of homes which need say 20V DC power.

EDIT: Based on limited answers/comments, the only co-design improvement I see for a city which only used this peak-skimming ACDC power would be to increase the distribution frequency well beyond 60 Hz (like airplanes do). Of course, I'm still hoping for other distribution options and novel ideas. (And, for a new future question, every option leaves me wondering how total installation cost would compare to having distributed solar panels and batteries everywhere, which seems to be the perfect fit here.)

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  • \$\begingroup\$ They already deal with whatever the typical mix is so a "suddenly tomorrow" scenario is unrealistic, BUT may be what is already happening. 600W uncorrected per average home sounds high (to me). But may not be. \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ DC takes way more complexity (circuitry and more expensive hardware) to pull off safely and reliably; it's not going to happen, or at least not for a long time. || FCC doesn't regulate what's on power lines, per se; they're concern starts at 9kHz. \$\endgroup\$ Commented yesterday
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    \$\begingroup\$ Where did that "3kW per home" come from? I have 100 A service, or 22 kW, same as my generator. \$\endgroup\$ Commented yesterday
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    \$\begingroup\$ @AnalogKid I don't know what the true max is, maybe I should have written 6kW, but I doubt they can get everyone near their breaker max (mine is 18 kW) at the same time. Also, the utility company probably spins up extra generators on extra hot days, so let's say it's a perfect weather day when the utility company tries to run in minimal mode (but all the users are skimming off the peaks with no PFC, so maybe this isn't very efficient in the end). \$\endgroup\$ Commented yesterday
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    \$\begingroup\$ Those are basically the same problems from the point of efficiency of energy transfer. If cos phi<1 then there is substantial current in the transmission line that basically moves power back and forth (from/to inductances and/or capacitances) without doing useful work but with I^2*R losses in wires. Rectifiers loaded with capacitance have heavy 50/60 Hz harmonics currents that also only lead to I^2*R losses in wires. So generally it's the same problem. \$\endgroup\$ Commented 20 hours ago

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It wouldn't make sense to distribute low-voltage DC among groups of houses — the wiring losses would be prohibitive at any meaningful level of power. But it would make sense to do the conversion within each house, like having a single largish 48 VDC power supply with PFC to power local DC loads, possibly using a point-of-load DC-to-DC converter to get lower voltages. I'm doing this already to some extent with LED lighting.

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  • \$\begingroup\$ First, it's nice of you to add PFC for your 48V (and lower) setup since I really don't see that as helping you, just helping your utility company. Anyway, if we designed the utility generation/distribution and your DC setup together for best efficiency, I still wonder if the generation/distribution part would change significantly (and I am still thinking that it would be AC distribution, but maybe a different frequency). I guess from your answer, you're saying it would not. \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ @bobuhito, a 48V system in your own home has benefits beyond the utility company. Firstly, it is assumed that the single conversion from 120->48V combined with the eventual load voltage 48V->??V is more efficient than doing 120V->??V directly. PFC reduces peak currents which in principle allows you to route things with smaller wires (at a consistent input voltage). Lower voltages have less safety implications (<60V and <30V being the two major delineations if my memory serves me). \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ This doesn't sound like a viable solution, because of copper costs and all the extra outlets. I suspect that if PFC became an issue with utility companies, they'd attempt to push for lower wattage thresholds to trigger more PFC-equipped devices. I now want to know how many feet of 14-gauge copper Romex you can buy with the price differential between a 75W PFC supply vs. a 75W "dirty" supply. \$\endgroup\$ Commented yesterday
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The utility companies already install PFC such as static VAR compensators as a standard part of the grid. How many houses require what level of compensation is a standard part of grid design, so you really don't need to worry about this yourself.

As other answers have already said, it doesn't make any sense to distribute low-voltage DC across any distance. LVDC inherently needs a higher current, which either produces more losses through resistance for any given piece of wire, or needs a radically thicker (and hence much more expensive) piece of wire for a given load.

Also power factor is merely a feature of grid loading. If you distributed DC at any voltage, for sure you wouldn't get these effects on phase (because there isn't any phase), but you absolutely would get the supply voltage being dragged down as load increased. This is all merely a detail of asking "has my electricity supply been designed to deal with expected demands?" (And this isn't a trivial question, in part because the word "expected" depends on whether that was expectations in 1920 or 2020, and we don't know what your infrastructure looks like!)

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  • \$\begingroup\$ Thanks for the PFC SVC reference. For the record, this seems to be more for compensating reactive current, not for compensating the non-linear peak-skimming current I am talking about here, though they overlap (i.e., series inductance helps peak-skimming). \$\endgroup\$ Commented 23 hours ago

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