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Major power failure affects homes and transport (bbc.co.uk)
69 points by zimpenfish 69 days ago | hide | past | web | favorite | 47 comments

There was confusion on Twitter how a frequency drop could cause a power outage. It's the other way around: loss of power/a plant leads to a drop in frequency. Here's why:

Imagine a generator spinning at 50 rpm (for the sake of simplicity). Now if the load on the generator is larger than the power it can provide, it will be slowed down and the frequency goes down. If the load is lower than the power output of the generator though this surplus goes into spinning it up, raising the frequency.

There are plants that can more easily vary their output which are used to manage these fluctuation and providing frequency control.

A pretty new and fast one is the Hornsdale Power Reserve in Australia, based on Tesla Powerpacks which can react in milliseconds, instead of seconds and minutes.

Yup. The synchronous speed of a motor is directly proportional to the frequency and number of poles in the motor. The formula RPM = 120f/p is used to solve for speed given f in Hz and p is the number of poles. Poles being one of the N-S halves in a magnetic pole pair. So the minimal number of poles in an AC induction motor is 2 and increases by 2. Typically, most AC induction motors are of the 2 and 4 pole variety as well as the less common but usually available 6 pole. The same goes for generators. The more poles, the slower it turns but torque increases proportionally. In ye olde days frequency was converted using motor generators. A 50<->60 hz system matches up at 600 RPM so a 10 pole on the 50Hz side and 12 on the 60Hz side (complex and expensive designs).

Using that formula, a 2 pole generator running at a synchronous speed of 3000 RPM will produce 50Hz. Using that 50Hz to power a 4 pole squirrel cage motor will cause it to run at just under synchronous speed, usually 4-5% below synchronous speed at full load (it will spin slightly faster, towards synch under no load). So about 1450 RPM. The reduction in speed is called slip and is what generates torque as the rotor has no magnetic field of its own, it depends on slip to generate the counter field to push the rotor along.

Synchronous motors avoid slip by having their own magnetic field from permanent magnets or a wound armature on the rotor fed DC from slip rings or rotary transformer. Coincidently, a synchronous motor and AC generator or alternator are almost the same machine. The basic idea is a magnetic field mechanically spun around pushes electrons around in the stator windings. Sort of like a propeller pushing through water, the magnetic field lines push and pull electrons along the wires. If the field is too weak the voltage will sag as load increases. You can visualize this as weak field = propeller made of rubber, flopping about and can't push much, full strength = made of steel. If the mechanical power source is weak or overloaded, the shaft speed will drop as well as voltage.

You are literally transmitting the generators rotational speed along the wires and motors follow. Adding generators means they have to be in phase so must be brought up to speed AND phased in before being connected to the grid. This is called synchronizing. So thanks to my long winded motor/generator post you can see how a large load can drag down frequency.

I’m not an expert - but I understand that while this is true (generator loss causes frequency to drop), this drop in frequency can in turn trigger actual “power outages” for users.

Automated systems respond to sagging frequency by shedding loads - reducing the demand for power, so that the frequency can increase and a new equilibrium can be achieved. The goal is to avoid an uncontrolled cascade across the power network as demand outstrips supply; this is substantially harder to manage than a short interruption.

The UK does have battery-powered frequency management services, but it looks like it was quite a large and sudden drop in generation capacity that caused this deviation, and it took several minutes before it was back to normal. Not totally sure what it was yet, but sounds like a gas turbine generator suddenly tripped, along with a nearby offshore wind farm, taking out about a gigawatt of capacity that normal frequency stabilisation couldn’t handle, resulting in load shedding.

Weather has been unusual as hell today, sunny one minute 50mph winds and torrential rain the next.

Or you could pay people to put a device on their air conditioner or water heater or car charger that’ll back-off when the frequency dips.

Conservation seems way more sensible than building new and advanced capacity.

They do that too, with large commercial users with loads that can easily be shed for short periods such as blast furnaces, aluminium smelters, refrigeration systems etc.

With car charging, they're doing one better, and can feed power back into the grid: https://www.ovoenergy.com/electric-cars/vehicle-to-grid-char...

Agreed, but we now have the technology to do these at much smaller scales, which, in aggregate, account for a lot of the load.

It just bother me when we focus on big industrial solutions.

We had the right idea with PV solar: why build a giant farm owned by ??? when we already have these structures everywhere tilted toward the sun and grid-connected.

> Agreed, but we now have the technology to do these at much smaller scales, which, in aggregate, account for a lot of the load.

A lot of companies have this capacity, but are waiting for the right environment to deploy it. Smart fridges, aircons, nest thermostats, electric cars with Wifi, etc. They have all been built with the capability to load-shed or even power the grid at a moments notice, but the manufacturers refuse to just do that for free - they want to be paid.

Many of those products were even sold at a loss because the companies expected to be paid by electricity networks for their fast-response stabiisation services.

Today, they aren't allowed to participate in the power markets, and anyway, markets are settled on a half-hourly basis rather than the 1-second basis that would earn them the most money and provide the most reliability for the grid.

This is all a politics problem within electricity regulators (who would much rather stick with the status quo, leaving some power stations underutilized, rather than pay these 'unreliable' web 2.0 companies). Nearly none of it is a technical problem.

Iunno, appliances (via energy star?) get more efficient all the time.

Not sure why they couldn’t become more adaptive too. A kWh isn’t a kWh, but energystar treats them that way.

That's very interesting, do you have any sources for that? I'd like to learn more. Especially on the topic of second-by-second settlement.

Given the frequent reports we get about the insecurity and fragility of the US power grid, is the UK grid as bad and is this going to be just a business-as-usual oopsie or something more sinister?

(Not an expert)

The UK grid is actually pretty well maintained and resilient - and controlled power outages can actually be a positive thing in this sense. It looks like a couple of generators failed within a short period, causing a sudden loss of about a gigawatt. When the frequency drops as a result, automated systems start tripping to prevent a more widespread collapse - it’s much easier to restore power to customers who have been isolated than to recover after a more widespread collapse, like the US northeast blackout in 2003.

Yeah, apparently these power outages only lasted a little under an hour for the folks affected. The big disruption came from it taking out heavily-used sections of the train network during the evening commute and the operators seemingly not having an easy way to bring those back into operation.

The problem seems to be that individual trains have faulted and apparently cannot be restarted without a visit from an engineer. With multiple faulty trains blocking lines, nothing can move.

>The UK grid is actually pretty well maintained and resilient

Also prefixed by not an expert here; but know a few in the industry and somewhat keep up with it.

The push away from coal to other sources of power (combined with the closure of gigawatts of nuclear power) has put the network under more stress than it's been in the past few decades [1]. I'd expect more of this in the future in cases of multi generator failures; there just isn't that much in the way of generation to take up the slack.

Luckily we're in summer where demand is much lower, if this was to happen in winter the outcomes could have been much worse.

//edit - Just to be clear though, this does seem to be totally benign and could have happened to any other well equipped grid. A gigawatt of power dropping out in such a short space is going to result in some kind of load shedding. Denorwig spins up fast; but not that fast.

1. https://www.bbc.co.uk/news/business-33527967

Outages of this scale are pretty much unheard of in the UK

Wait until the dover-calais power grid interconnector goes down on nov 1st.

I assume you're referring to Brexit. Any indication that this would actually affect the power grid?


“UK-issued Renewable Guarantees of Origin and Guarantees of Origin for combined heat and power will no longer be recognised in the EU. If an existing contract with an EU countries’ electricity supplier or trader requires an EU-recognised Guarantee of Origin, it is possible that the contract could be compromised”

... yet mysteriously, the trains are often this bad

There have been similar reports about the UK grid for as long as I can remember (multiple decades).

The squeaky wheels get the grease.

As for the UK today, certainly anywhere along the South Coast was untroubled by this (including the RJ Mitchell windtunnel[0], which was quite literally a blast).

[0] https://www.southampton.ac.uk/windtunnels/index.page

The US power network is on 110v, this is reason enough to call it fragile opposed to the 230v in the UK

Nominal voltage in the US is 120 volts. It hasn't been 110 volts since the 1970s.

And it's still creeping upward. The average voltage at my house over the last year was 121.9 volts. https://i.imgur.com/6RMZnXd.png

Only the last bit to your house or apartment is 110v. That doesn't make it more or less fragile, it just means you need more amps and correspondingly more wire in the final hop to the customer.

The difference in voltage results a real difference is in the distribution and how the phases are delivered - due to the lower voltage limiting how far it's economical to distribute the last mile, the US has many smaller transformers (those big cans on poles that catch fire sometimes), whereas Europe has fewer bigger transformer stations.

Although this has the opposite effect - the 120V system is less fragile, since the points of failure are more distributed (a blown transformer will affect fewer customers).

See: https://electrical-engineering-portal.com/north-american-ver...


Its not often we have power outages. And when we do they usually have "understandable" reasons ( lightning etc..) And are localised.

This seems different.

It's a bit pre-emptive to start witch-hunting, though.

The 2003 Northeast US/Canada blackout was caused by a race condition: https://odetocode.com/blogs/scott/archive/2004/04/11/blackou...

> The 2003 Northeast US/Canada blackout was caused by a race condition: https://odetocode.com/blogs/scott/archive/2004/04/11/blackou....

No, it wasn't. The race condition caused First Energy to not notice that their energy grid was one more line trip away from catastrophic failure. But there were four line trips that day caused by power lines hitting trees and shorting, the last of which triggered the dynamic instability that caused the blackout. First Energy had a whole host of issues that together caused the blackout, and the race condition in the alarm monitoring system was but one of them.

The full report is actually an interesting read. Essentially, the key problem that caused the massive cascade was that the line trips meant that large loads of power had to reroute long distances to get to the Cleveland demand area, and the non-infinitesimal amount of time it takes for the power to establish that route caused several lines to trip, to the point that the demand was cut off from the network before the supply surge reached it.


There's the matter of the well attributed 2016 US election interference operation, generally the hundreds of billions they spend on their military, and stuff like https://www.us-cert.gov/ncas/alerts/TA18-074A. There is lots of documentation of Russian state interference in the Brexit referendum that is publicly available. There long standing interest in disrupting NATO and the EU are just basic common sense.


Interestingly on a quick glance the UK does not seem to be part of the synchronized EU grid and has only a DC connection to France that provides 5% or less of the electricity used at any time. I may be wrong but the grid does not seem to be directly affected by the clusterfuck that Brexit will be.

That's a very generous interpretation of the facts.

We actually have lines going to Netherlands (which in turn pulls from Germany) and France, and one incoming that connects us to Norway.[0]

I have friends who work in power stations up and down the country and they describe it as a "power sharing" situation, our grid feeds Netherlands and France (to a lesser extent at least), but more often we pull from them to fill our peaks.

We actually have links to many countries it seems: https://blogs.platts.com/2019/01/31/uk-electricity-links-eur...

[0]: https://en.wikipedia.org/wiki/Transmission_system_operator

That's right, the interconnectors are all bi-directional.

They move electricity where it's needed according to market demand: when the wholesale price is higher in Britain than in (for example) France, the UK imports electricity.

When the wholesale price is higher in France, which can happen during winter demand peaks as France has a lot of electric heating, the flow is reversed and the UK exports electricity.

Thanks, your and the other replies left me better informed than before.

Britain currently has HVDC interconnectors to France (2 GW), Belgium (NemoLink, 1 GW), and Netherlands (BritNed, 1 GW), as well as 2 interconnectors with Ireland (East-West and Moyle, 500 MW each)

In addition, there are at least 5 new interconnectors due to be completed by the early 2020s: 2 more to France (IFA-2 and ElecLink), 2 to Norway (North Sea Link, NorthConnect), and 1 to Denmark (Viking link).

Thanks, I should have researched the HVDC interconnections, I didn’t expect them to be this relevant. Very interesting!

there's several UK power stations that are legally required to run at less than full capacity due to EU's large combustion plant directive (+ other later directives)

after leaving: in the event of a serious short term problem they can be spun up relatively easily until extra (better) capacity can be brought online

All of the UK power plants that were affected by the Large Combustion Plant directive have since been closed permanently. The last one, Ironbridge, closed in November 2015.

All remaining coal-fired power stations are legally required to close by 2025, but that's a UK decision, not an EU one. In reality they are being used less and less already, and most are likely to close well before 2025.

> "large combustion plant directive (>>+ other later directives<<)"

the follow up directive is still very much in effect and has placed operating restrictions (mostly load and hour limits) on many UK power stations


these can be lifted on November 1st (if required), and would radically change the economics of the UK's generation market

(not that burning coal is a good thing, but it's better than rolling blackouts)

> "these can be lifted on November 1st (if required), and would radically change the economics of the UK's generation market"

How so? Coal-fired power plants are already uneconomic in the UK, and the ones that continue to operate do so with a government subsidy, the "Capacity Market", which essentially pays them to remain on standby in case they are needed.

The European Commission actually ruled recently that the CM was illegal state aid, so if anything, Brexit just means that the CM can continue operating.


The headline (which has since been updated on the BBC) is somewhat misleading, in that the power outage has affected a large area of the UK and is not specifically affecting transport infrastructure.

"Major power failure affects homes and transport"

Is a HILARIOUS headline! In a region with many electric trains it's double-funny! In the future they'll be able to make homes levitate on electrical power (just because they can, and for views and breezes, neighborly one-upmanship etc)and power outages will have even more spectacular effects!

And it will be funnier still!

I link a few old news with it : First there was a news that electric grids are hackable. And Russians might be after those. Then there was a news that White House called for some of the power transmission switches be turned manual, which are now automatic. Next there were a bunch of large and sudden power failures in large cities all over the world. And now this.

Maybe there isn't a link. Just a possibility.

More likely that the huge storm sweeping the south of england is the cause

Imagine I were a hacker who had hacked into a big gas turbine power plant.

To create maximum damage, I am going to want to time my attack within moments of another generator going down. The UK grid can tolerate one big failure, but not two at the same time.

So I sit... I lie in wait... For maybe months... As soon as I see another big generator fail and cause a sudden change in frequency, then within a couple of seconds, I trigger my exploit to shut down my powerstation too.

The storm might have caused one outage, and a hacker the other.

Any decent hacker with this plan in mind will try to hide their tracks. They'll inject a 'glitchy' sensor reading to trigger the failure. They'll make sure all their malware auto-uninstalls itself within milliseconds of the incident, so any investigation sees a glitch in a sensor reading and can't track down the real cause.

oh come on. if power goes down, the it is Russians. probably old outdated powerlines are the reason.

Just saying... if I was a hacker, I would hack in a way that made it look like old failing equipment

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