How to ramp up a factory consuming a lot of energy?

This is no powerplant-level story, but sometimes there are high startup currents were you didn&#x27;t expect them:<p>On one of my first IT jobs at a big manufacturing company my team was tasked to find out why there are regular power outages in some printer rooms (there were rooms with shared printers on each floor of the office building). There were always some tripped circuit breakers and the facility management had to dispatch someone to put them back on. Between those incidents were always some weeks were nothing happened, but when it happened it affected a lot of printer rooms.<p>In the end we found a monthly cronjob on a central printing server which triggered a testpage print on all connected printers. Took us quite some time since no one ever saw those test pages. Never underestimate the needed current for a room full of colour laser printers coming to live all at once.

A small - and somewhat related - anecdote.<p>New Zealand had to build an aluminum plant in the 1960s and figured out it would be more efficient to bore miles underground, build turbines, install a huge power station, and wire it tens of miles to the smelting plant. It relies on a vertical drop between Lake Manapōuri and the open ocean to create the gravitational potential to turn the turbines. When the smelting station doesn&#x27;t use the full capacity the power station has to immediately reduce output, otherwise it can overload the transmission lines to the rest of the grid.<p>Manapouri Power Station is the name if anyone is interested in reading more. It has an interesting history. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Manapouri_Power_Station" rel="nofollow noreferrer">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Manapouri_Power_Station</a>

Relevant story: back in grad school, I did a few experiments in the (old) MIT wind tunnel, now torn down.<p>Before starting up the fans, the guy running the control booth picked up the phone and had a short conversation, roughly<p>&quot;Hi, this is [name] at the wind tunnel; can we turn it on?&quot;<p>[someone on the other end replies]<p>&quot;Great, thanks.&quot;<p>I asked who he was calling, and he explained that he had to check with the power company before powering it on. This was mid-winter, so grid demand was low; apparently during the summer (when everyone has ACs on), the start-up load could cause brownouts!

PJM, the grid operator for the northeastern US, has a &quot;demand response fact sheet&quot;.[2] There are various ways to buy large amounts of power. Big users will have a connection to the pricing system, getting better prices during low demand periods, higher prices during high demand periods, and shutoffs during very high demand periods.<p>Big power consumers usually pay for power at grid market rates, which vary from hour to hour. So they&#x27;re tied into both the market system and the control system. This is done via a Curtailment Service Provider.[2] Some of those are power distribution companies, and others are just brokers.<p>Here&#x27;s one in California.[3] There&#x27;s a phone app, a web page, a connection to your meter, and an API for your own load&#x27;s control system. Large power consumers connect to them, and they connect to the grid operator, which is CAISO for California. Once everything is connected, they can remotely tell your systems to reduce their load and verify that has happened, for which you get a price break.<p>There&#x27;s the Peak Load Management Association, which you can join if you buy power by the gigawatt.[4]<p>[1] <a href="https:&#x2F;&#x2F;pjm.com&#x2F;-&#x2F;media&#x2F;about-pjm&#x2F;newsroom&#x2F;fact-sheets&#x2F;demand-response-fact-sheet.ashx" rel="nofollow noreferrer">https:&#x2F;&#x2F;pjm.com&#x2F;-&#x2F;media&#x2F;about-pjm&#x2F;newsroom&#x2F;fact-sheets&#x2F;deman...</a><p>[2] <a href="https:&#x2F;&#x2F;www.pjm.com&#x2F;markets-and-operations&#x2F;demand-response&#x2F;csps.aspx" rel="nofollow noreferrer">https:&#x2F;&#x2F;www.pjm.com&#x2F;markets-and-operations&#x2F;demand-response&#x2F;c...</a><p>[3] <a href="https:&#x2F;&#x2F;cpowerenergy.com&#x2F;wp-content&#x2F;uploads&#x2F;2018&#x2F;01&#x2F;CAISO_DRAM_Full-Download_6.pdf" rel="nofollow noreferrer">https:&#x2F;&#x2F;cpowerenergy.com&#x2F;wp-content&#x2F;uploads&#x2F;2018&#x2F;01&#x2F;CAISO_DR...</a><p>[4] <a href="https:&#x2F;&#x2F;www.peakload.org&#x2F;" rel="nofollow noreferrer">https:&#x2F;&#x2F;www.peakload.org&#x2F;</a>

Other interesting fact is how grid uses frequency to communicate the load demand.<p>Load drops, the big spinny generators stop having so much resistance and accelerate.<p>Load increases and the big spinny generators have more load, synchronously slowing down.<p>So in simplest system just feeding your generator more when frequency is below nominal and less when it is above is enough

Collective human knowledge just blows my mind sometimes.<p>Consider how many obscure but useful, necessary even, things we&#x27;ve learned over the past thousand years.<p>Before the internet it would all be hidden away, only quickly available to specific experts in their fields.<p>You&#x27;d have to go to a university library and dig for hours.

A fact in this Wikipedia article shocked me into understanding how much juice an aluminum smelter plant requires.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Shearon_Harris_Nuclear_Power_Plant" rel="nofollow noreferrer">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Shearon_Harris_Nuclear_Power_P...</a><p>&quot;The Shearon Harris site was originally designed for four reactors (and still has the space available for them), but cancellation of an aluminum smelter plant in eastern North Carolina in the 1970s resulted in three of the reactors being canceled.&quot;

Another anecdote to share: at my dad&#x27;s office, while doing a disaster recovery exercise, they realized that their startup power requirements exceeded what their electrical system could supply.<p>Systems had been slowly added over the years, but because the power system is pretty reliable around here, they&#x27;d never had to start things up from a complete power failure.

Ew, you mean they have to talk to a human on the telephone?<p>---<p>We built a whole application to manage a certain workflow between multiple systems, and our users kept using email instead, because it turns out that the users on the other end don&#x27;t check the system, but they do check their email.

One question about the grid I&#x27;ve never wrapped my head around:<p>So the entire grid is in phase, by which I mean every generator, load, &amp;c is operating on the same AC pulse (<i>handwave-handwave</i> ignoring smaller loads, transformations, etc.). But that phase isn&#x27;t instantaneous; it&#x27;s near-light, and the grid is long enough for that to matter in places.<p>So every point in the grid can&#x27;t be perfectly in phase with every other point, right? Because we have both lightspeed delays and loops, so even if point A is receiving power from two substations in-phase, point B (with different lengths of wire to those two substations) should be receiving it out-of-phase, right? How do we balance that in the grid?

I operated the dryers at a coal mine in the 1980s. We had to start the exhaust fans with the dampers closed and then slowly open them, or we&#x27;d take out the power for all of Northeastern British Columbia. I know because I knocked the power out by mistake one night. I suspect that high-drawing factories must employ similar strategies to slowly increase the draw.

&gt; Each 775-ton flywheel can spin up to 225 rpm and store 3.75 GJ,[47] roughly the same amount of kinetic energy as a train weighing 5,000 tons traveling at 140 kilometres per hour (87 mph). Each flywheel uses 8.8 MW to spin up and can generate 400 MW (briefly)<p>Does that mean that the 775 ton flywheels could come to a complete stop in less than 13 seconds if fully used up?

In the past, it was solved this way.<p>A heavy contactor powers on stage 1, stage 1 powers another heavy contactor powering stage 2, stage 2 does the same with stage 3.<p>When mains voltage is too low, the contactor cannot close. This way this allows for tens of milliseconds of separation in between power ons.