[discussion] DC (direct current) power network
[discussion] DC (direct current) power network
As we all know, AC won the "War of the Currents". The reasoning behind this is that AC voltage is easy to convert up/down with just a ring of iron and two coils. And high voltage allows us to transport current over longer distances, with less loss.
Now, the War of the Currents happened in 1900 (approximately), and our technology has improved a lot since then. We have useful diodes and transistors now, we have microcontrollers and Buck/Boost converters. We can transform DC voltage well today.
Additionally, photovoltaics produces DC naturally. Whereas the traditional generator has an easier time producing AC, photovoltaic plants would have to transform the power into AC, which, if I understand correctly, has a massive loss.
And then there's the issue of stabilizing the frequency. When you have one big producer (one big hydro-electric dam or coal power plant), then stabilizing the frequency is trivial, because you only have to talk to yourself. When you have 100000 small producers (assume everyone in a bigger area has photovoltaics on their roof), then suddenly stabilizing the frequency becomes more challenging, because everybody has to work in exactly the same rhythm.
I wonder, would it make sense to change our power grid from AC to DC today? I know it would obviously be a lot of work, since every consuming device would have to change what power it accepts from the grid. But in the long run, could it be worth it? Also, what about insular networks. Would it make sense there? Thanks for taking the time for reading this, and also, I'm willing to go into the maths, if that's relevant to the discussion.
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Well, most all DC generators these days are actually AC alternators with the output rectified, because alternators can be run a lot more efficiently. So you're already losing on efficiency there.
You need to consider the consumer side as well. Dinky residential loads like your computer would be fine on DC. But most of the world, especially heavy industry, runs on synchronous or induction AC motors, big ones. Big huge tens-of-megawatts motors that often run upwards of 97% line efficiency, which is insane for any industrial process.
The best you could replace those with would be modern brushless DC motors, which require really expensive inverter controls that die frequently due to the magnetic transients and still top out at an efficiency of only 90% if you're lucky. And that would incur huge costs that just aren't worth it.The best you could replace those with would be modern brushless DC motors, which require really expensive inverter controls that die frequently due to the magnetic transients
Wow, is this why my new brushless cordless tools have had more issues than my 25 year old cordless tools?
I mean, yes and no. A lot of that is modern tools are going to be more carefully engineered to operate as close to failure as possible, as to advertise more power with a cheaper device. Thry have small wires and encoder sensors that can be prone to failure.
Yes, the driving electronics are also sensitive, however magnetic transients are less of a deal on the scale of a cordless drill. When dealing with huge motors, those can be significant multi-kilovolt spikes that make solid state components Very Very Mad.
But the brushless motors in a drill also do not have brushes that wear down rapidly in a very dirty/dusty contaminated environment like older power tools would. So it's a bit of a 50/50.spikes that make solid state components Very Very Mad
Hahaha, now I'm picturing an IC with an angry face just before it farts out Magic Smoke.
Yea, I've had a couple new impact drivers needing the controller replaced, I assume they're a package.
While my 25 year old, abused impact of the same brand keeps chugging along, eating 2x as much battery for the same job.
Hahaha, now I’m picturing an IC with an angry face just before it farts out Magic Smoke.
Well, that's basically how they behave too lol. Solid state power components are generally not very tolerant and require careful surge suppression and filtering to not have them blow up frequently.
I bet if you took that 25 year old driver apart, sanded off the commutator rotor, and put new brushes in it you'd suddenly find it'd have more power and use less battery. (And thats something you can do with older tools!)
When brushed motors get old and oxidation/dirt builds up the resistance across the brushes to the rotor coils grows and you'll lose motor efficiency.