[HN Gopher] Turning off electrical grids to prevent wildfire- a ...
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Turning off electrical grids to prevent wildfire- a complex,
technical operation
Author : rntn
Score : 29 points
Date : 2024-04-14 19:00 UTC (4 hours ago)
(HTM) web link (theconversation.com)
(TXT) w3m dump (theconversation.com)
| puzzledobserver wrote:
| The Practical Engineering Youtube channel has a very interesting
| video on black starts of an electrical grid [0]. Are there any
| additional challenges in turning a grid off?
|
| [0] https://www.youtube.com/watch?v=uOSnQM1Zu4w
| idiotsecant wrote:
| There's a pretty big challenge, which is that you aren't
| turning off a grid at all -just particular transmission lines.
| Your typical power flows rely on those lines being up, and
| without them strange conditions can occur. Its sometimes just
| as bad to have an unusually lightly loaded line as it is to
| have an overloaded line. Lightly loaded lines with lots of
| generation end up messing up line voltages due to capacitive
| loading. You can end up having to shut down a line or taking
| other remedial action like shutting down generation because not
| _enough_ power is flowing through a line.
| ckdarby wrote:
| I suspect we'll see more openness to this with homes in the
| future coming with batteries to power for 12-24 hours without the
| grid.
| robocat wrote:
| In my experience 12-24 hours won't help you enough in a city,
| and is woefully inadequate in rural areas.
|
| There are better ways to spend your money to cover risks than
| batteries. Maybe if you were getting a battery for other
| reasons, or as a luxury if you are wealthy enough.
| toast0 wrote:
| I think if you have a big enough time of use differential,
| and you have significant use during peak pricing, you can
| justify a local battery system for peak shaving and get
| backup power 'for free' or vice versa.
|
| 12-24 hours would have outlasted any outage I've experienced,
| until I moved to my current place, but it has a propane
| fueled whole house generator (and low utility rates with no
| time of use component; i haven't attempted the math, but I'm
| pretty sure running from my generator is way more expensive
| than utility power... OTOH, I've had many utility failures
| and only one generator failure (12v battery failed due to
| charger failure))
| amluto wrote:
| I would like to know why grid operators turn portions off instead
| of installing devices to mitigate the fire risk when a fault
| occurs. "Rapid Earth Fault CLearance" devices (REFCL), also known
| as ground fault neutralizers, are a newish but commercially
| available technology that massively reduces current, and thus
| heating energy, delivered into a ground fault. In testing in
| Australia, a REFCL-protected line was intentionally dropped into
| dry plants without setting them on fire.
|
| What gives? I doubt these devices are so expensive that they're
| worse than the cost of "public safety power shutdowns" or of the
| billions of dollars that utilities are spending, and charging
| customers for, for undergrounding of lines and extra tree work.
| mschuster91 wrote:
| > I would like to know why grid operators turn portions off
| instead of installing devices to mitigate the fire risk when a
| fault occurs.
|
| The stuff you're mentioning is - at least from a quick Google,
| I'll admit that - only certified in Australia. Even here in
| Germany, introducing that onto the grid would take years for
| certifications. Bureaucracy moves slowly.
|
| Then, you'd need to upgrade _a lot_ of transmission lines
| including the regional distribution grid (i.e. < 100 kV), a
| single unprotected line in a danger-prone area is enough to
| start a deadly fire. And there are a looooot of power lines
| that haven't had an inspection for decades - the hook that
| caused the 2018 fire was almost a century old [1]. And so,
| instead of inspecting, maintaining and upgrading the many
| thousand km's of national and regional lines, shutting them
| down during peak fire condition times is cheaper.
|
| IMHO it only makes sense to install REFCL devices as part of a
| general overhaul of an entire transmission grid _area_.
|
| [1] https://www.wsj.com/articles/this-old-metal-hook-could-
| deter...
| toast0 wrote:
| Because they already have the ability to turn portions off.
| Installing a lot of new equipment means regulatory effort to
| get a plan approved, and a lot of installation labor.
|
| I imagine these systems will be put in place over time, but I
| was just looking at Wikipedia on Reclosers and they said
| Sensitive Ground Fault protection reduces the risk by 80%; if
| the risk is high enough, that probably still warrants
| deenergizing risky lines at times.
| sanderjd wrote:
| The thing that was most unclear with this incident in Colorado
| was: How did they decide which areas to shut down? It didn't make
| me feel like the people in charge knew what they were doing, when
| we left our neighborhood where the power was intentionally turned
| off (for over a day) to go to our friends' house where it was
| kept on, despite them having much stronger winds both in the
| forecast and in actuality. Their house is also in an area with
| much higher fire risk, surrounded by dry windswept vegetation.
| It's hard to trust an organization that says "we're turning off
| your power due to your area's unique risk of fire" when that
| conclusion seems incomprehensible to anyone aware of the weather
| and geography of the area. It's very hard not to wonder whether
| they are ignorant or are not being forthright. Maybe there is
| some information that would show that they made the right
| decisions, but if so, they certainly haven't shared it yet!
| zmj wrote:
| Agreed this was confusing. It seems like the risk factors that
| would lead to turning off a neighborhood (non-buried power
| lines, exposure to wind and available fuels) should have been
| known and announced in advance.
|
| I'm in Lafayette, and it seemed strange that our power was on
| when neighborhoods in Louisville and Erie were out.
| sanderjd wrote:
| Yep, and pretty much the entirety of Boulder preemptively
| turned off, _but not_ the areas south along 93 and to the
| east into Arvada near Rocky Flats, which are the exact super
| dry and windy areas where the Marshall Fire began.
|
| I actually do think there must be some plausible explanation,
| but it's hard not to feel sympathetic to the people who are
| convinced it is a tit for tat by Xcel, targeted at people who
| have been involved in recent legal confrontations with them.
| There are good reasons they aren't being given the benefit of
| the doubt here.
|
| I honestly worry more that truth is they were just winging it
| without any strong process or data with which to make the
| decision, and that this is their plan moving forward.
|
| But the good news is that the PUC investigating what happened
| is the way to get these answers, and is exactly what Governor
| Polis is pushing for.
| michaelrpeskin wrote:
| My power wasn't turned off - I did get the "we might have to
| turn your power off" warning though.
|
| I live in probably one of the worst areas for wind, and had
| gusts to 100 that Saturday night - didn't get any sleep!
|
| I had studied the local grid a bit for some other reasons a
| while ago, here's how I would put the pieces together:
|
| My neighborhood is all buried lines, and everything is buried
| starting right near our substation. No raised distribution
| lines to worry about. However, it's still not really
| distribution lines that are going to cause wildfires, it's the
| transmission lines that go through the dry forest. Wind taking
| out a distribution line isn't that big of a deal, and it
| wouldn't cause much downstream fire risk.
|
| My co-worker who lives about a half mile from me was without
| power for nearly 2 days. In other power outages, we've compared
| notes. Even though they live closer to my substation than I do,
| they're on a different substation.
|
| The transmission line that powers their substation goes right
| through the mountains. It's really close to lots of dry fuel
| and the towers are very far apart, so it would be easy to get
| those lines to swing in the wind. Additionally, the way the
| winds blow, if their lines did arc and cause a fire, the wind
| would sweep it right into town.
|
| So you really don't want to look at "why was my neighborhood
| without power, we didn't get much wind." You want to look at
| "where does my substation get it's power, and would an arc on
| that transmission line be catastrophic".
|
| At least in my immediate area, the substations that were shut
| down were exactly the ones I would have shut down just by
| looking at a map and saying "if it's windy and dry here, do I
| want an energized line?".
|
| I don't know about the decisions in the wider Front Range area,
| but I would be willing to bet that 1) it's a pain to de- (and
| re-) energize lines, so they don't do it without weighing the
| risk, and 2) much of our transmission lines out here are in the
| mountains to the west, which is terrible when you have westerly
| winds that will blow the fire into town, so they have a high
| risk weighting.
| ThinkBeat wrote:
| There is a bad snowstorm coming in folks. Snow, high winds and
| temperatures best thought about in Kelvins. Just joking with ya-
| all. Looks like we will be snowed in for a week or so. To keep
| ya-all safe, the utility will be turning off the grid. Remember
| to stay warm.
| zmj wrote:
| That's actually a real concern for using this strategy in
| Colorado in the fall. The Marshall Fire (mentioned in the
| article) was followed by snow and temperatures well below
| freezing. Sadly, this probably killed some pets that escaped
| the fire.
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