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I have a canine lodger with me and on our afternoon walk we pass close to three wind turbines. On Monday all three were spinning in the strong breeze, the middle one slowly came to a standstill, while the other two carried on, why would it stop? The next day it was spinning again. Anyone in the wind turbine game who can shed any light on it?
I'd love to know too. We used to live near two of them; there didn't seem to be any logic as to when one or both would be turning, whatever the wind or time of day. It was odd to see them very slowly stopping or starting for seemingly no reason at all...
is it not when the electruicity is no longer needed? Feather the blades to stop them turning?
Ours needs to stop before it can rotate into the wind.
I think it's based on demand. They also adjust how fast the blades turn, by adjusting the angle of them, and how efficient they are for the wind speed. The one that powered down could be the oldest with the most hours, requires servicing sooner than the others etc.
Power cut?
It was already windy enough so they could turn one off.
I asked a wind turbine engineer the same question a few weeks ago. Common reasons are too much wind, breakdown and demand. They shut off when there is no demand to preserve the components. Some of the older designs don’t have the ability to feather the blades and moderate the speed at which they turn in strong winds so they have to stop turning altogether.
They'd dispersed the contrails in that turbines sector
The earth was spinning fast enough so they could throttle back the fans.
It is the big fans that make the earth spin, right?
That is what I told my grandkids when they asked what they were for so it is now a "Grandad told me Fact!". Apparently that is a term the use to win arguments at home.
Usually depends on demand. With a fossil fuel power station you bung in a bit less coal or gas to turn it down, with a windfarm you turn a few turbines off.
Wind turbines are synchronous (always turn the same speed) to provide alternating current electricity as the right frequency for the grid so to reduce power you can feather the blades a bit or turn some of the off. You can't rotate them a bit slower like you might with an aeroplane propeller.
Kind of simple but does also beg the question of surely we could do something with that extra power on windy days. There a quite a lot of people trying to work this out!
Thermal turbines are synchronous too, our Parsons ran at a steady 3000 rpm with the load only affecting how many MW it was pumping out, you could drop that by reducing power output from the reactor.
Then there was phase tapping which was to do with adding or decreasing the amount of inductive load according to grid demand. Dunno how wind turbines manage that if at all.
Wind turbines are synchronous
Umm, no.
Wind turbines are asynchronous, DFIG, fully-converted, but not synchronous generators.
DFIG are I suppose the closest to synchronous, well a synthesised synchronicity anyway. But not really.
Unless of course I’m wrong. I am not a wind turbine engineer - though I did spend over ten years connecting them to the distribution system.
Its a bit self conscious and feels you're watching it.
Even wind turbines need a rest perhaps? (interesting observation and I have no clue)
Kind of simple but does also beg the question of surely we could do something with that extra power on windy days. There a quite a lot of people trying to work this out!
Pumped hydro would be a fairly simple way to store it. I'm sure that much smarter people than me are working on it.
They've stopped identifying as wind turbines and have decided they are statues.
Generally either related to demand or maintenance (although I do like the less boring answers above 😉 )
Pumped hydro would be a fairly simple way to store it. I’m sure that much smarter people than me are working on it.
Its a question of space. We have 4 hours or so worth of UK consumption from pump storage IIRC. We have nowhere to build a lot more.
but does also beg the question of surely we could do something with that extra power on windy days.
One reason why electric cars / home power storage may be the answer - when there's too much power being generated you can 'fill up' each individual power storage bank, owners can then sell it back to the grid during peak times when there's less wind.
However we are prob 50+ years away from this and would prob rely on new battery tech.
Semi related question - are they variably geared? They seem to have a preferred speed and don't seem to speed up when it's windy or slow down when its a gentle breeze. So, are they geared internally to harvest more energy from a higher wind speed to maintain a constant blade speed?
Wind turbines are synchronous (always turn the same speed) to provide alternating current electricity as the right frequency for the grid so to reduce power you can feather the blades a bit or turn some of the off
IANAWTE, but is this definitely the case for all designs? I keep a fairly close eye on wind turbines as a gauge of wind direction/speed and they definitely spin faster in stronger wind - at least the ones I commonly see. I assumed they had gearboxes to get the correct input speed at the generator part.
are they variably geared? They seem to have a preferred speed and don’t seem to speed up when it’s windy or slow down when its a gentle breeze.
No. Any given turbine model has a power curve and will be chosen for its site, so it'll get to its nominal power output at a certain wind speed and will be generating at that level at higher wind speeds. Eg:
I think it unlikely there's any significant link between blade frequency and grid phasing.
IANAWTE either. I used to work in the industry, but I dealt with the money, not the tech.
Semi related question – are they variably geared?
Not normally mechanically (though there’s bound to be one somewhere) though aysychronous slip, injected frequency in DFIG and electrical conversion in fully converted could be though of as electrical variable gearing.
We have 4 hours or so worth of UK consumption from pump storage IIRC. We have nowhere to build a lot more.
There is a bigish new one about to be built above Loch Lochy. https://www.coireglas.com/
Pumped hydro would be a fairly simple way to store it. I’m sure that much smarter people than me are working on it.
Its a question of space. We have 4 hours or so worth of UK consumption from pump storage IIRC. We have nowhere to build a lot more.
We do have lots of old mineshafts (and ability to dig more) though - I like this solution to storage rather than cycling everyone's EV batteries all the time (as well as the journey planning headache that brings)
The new one near Loch Lochy will more than double UK pumped storage capacity. Enough to power the UK for under an hour.
It will have 30Gwh storage.
UK demand right now 35Gw.
Storage is not feasible for anything more than smoothing out daily peaks in demand
Which is why wind power needs near 100% backup from gas.
Semi related question – are they variably geared? They seem to have a preferred speed and don’t seem to speed up when it’s windy or slow down when its a gentle breeze. So, are they geared internally to harvest more energy from a higher wind speed to maintain a constant blade speed?
No, AIUI the blade is optimized so it's at it's most efficient angle, at the modal windspeed, with the tip moving just below the speed of sound. As it gets windier the blades have to be feathered to keep the tip speed down.
Apparently they're also less clever than you'd imagine. For example if you have two or more large turbines together they'll synchronize with each other, even though they're both generating AC, which is converted to DC then inverted back to AC @50Hz. As each blade passes the tower you get a momentary drop in power, which is measurable in the grid, which feeds back to all the other turbines, until they're all in sync and then you end up with a bigger drop in power that's measurable elsewhere in the grid.
I'm just amused that there's a loch called Lochy. Is its last name McLochFace?
Apparently they’re also less clever than you’d imagine… …As each blade passes the tower you get a momentary drop in power, which is measurable in the grid, which feeds back to all the other turbines
That suggests the turbines are MORE clever than I'd imagine. I think I can understand how nearby turbines will sync in terms of their AC sine waves, but I can't see any mechanism for them to sync their blade positions relative to the tower?
That suggests the turbines are MORE clever than I’d imagine. I think I can understand how nearby turbines will sync in terms of their AC sine waves, but I can’t see any mechanism for them to sync their blade positions relative to the tower?
Isn't it the same thing?
If they are syncing with each other to a drop in power, then they are syncing to the tower position.
One reason why electric cars / home power storage may be the answer – when there’s too much power being generated you can ‘fill up’ each individual power storage bank, owners can then sell it back to the grid during peak times when there’s less wind.
However we are prob 50+ years away from this and would prob rely on new battery tech.
On a simpler level the technology to opt to only charge your care when there is lots of renewables being generated would be quite easy
That suggests the turbines are MORE clever than I’d imagine. I think I can understand how nearby turbines will sync in terms of their AC sine waves, but I can’t see any mechanism for them to sync their blade positions relative to the tower?
There's a DC step in between.
My (not an electrical engineer) understanding was that if you looked at the power produced by the turbines it drops as each blade passes the tower, that drop is measurable in the dynamo's AC, the DC bit, and the 50Hz AC. That effectively puts a drag on all the other turbines, the more power they produce the bigger the effect of the drag. So a turbine not in phase get's a bigger drag than one that's in phase. Until eventually all the turbines locally have the blades passing the towers in phase with each other.
Then the more turbines you get in sync, the bigger the effect becomes, and eventually they start to affect turbines further away. Because while transformers are good at filtering out high frequency noise in the grid, they do nothing to 'noise' that's more like 0.5Hz.
Just one of those big engineering problems that you never even know exists until you ask another engineer at a seminar "so how does X actually work" and you get a really long answer 😂
I like this solution to storage rather than cycling everyone’s EV batteries all the time (as well as the journey planning headache that brings)
It's not as big a deal as you make out.
If a car has a 50kWh battery, then you only need about 20% of that to run your house for a day. Seeing as the average car only does about 20miles a day (generally a lot less, which is depressing for other reasons) which is <10% of the battery. Then on a full charge you could run both the car and the house for about 4 days before the 'average' person even needs to think about journey planning.
Whereas the actual reality is that the grid (or you) would need to rely on your car for minutes/hours at most to power your home while demand is high.
A bit like the fossil fuel energy systems rely on people filing their cars up occasionally, then using that energy as and when they need it. If everyone tries to fill up at once it's a crisis.
UK power is metered and priced on a half hourly system, with traders and utilities buying and selling ahead based on demand expectations, supply capability of the different generators and weather forecasting for wind and solar. So when it's plentiful it's cheap and vice versa. The information is all there. Users timing demand from this is known as "demand side management".
I don't know the latest on it, having been out of the industry for a few years, but I suspect there's still considerable untapped potential.
Obviously there are home batteries, EVs, immersion heaters, appliances etc, through domestic smart meters, but I suspect they can be dwarfed by industrial applications of the same.
I’m just amused that there’s a loch called Lochy. Is its last name McLochFace?
It is but they keep that a bit low key.
Isn’t it the same thing?
If they are syncing with each other to a drop in power, then they are syncing to the tower position.
Yes, that's the same. Sync is being used to mean two different things. What I was meaning was that syncing the 50Hz waveform is a normal thing for a generator, but I didn't see how they would sync to a drop in power. But I think TINAS has explained it?
That effectively puts a drag on all the other turbines, the more power they produce the bigger the effect of the drag.
So if I understand that correctly, it's a result of the DFIG; the power that's fed in is affected by the other turbines, so it drops and that drags on the ones that are out of sync?
Pumped hydro would be a fairly simple way to store it. I’m sure that much smarter people than me are working on it.
There’s big investment going on in large battery storage farms in some parts of the world, plus some novel ideas like a ‘hot sand’ storage system that the Israelies are experimenting with.
On a simpler level the technology to opt to only charge your care when there is lots of renewables being generated would be quite easy
It's called Intelligent Octopus and it's available right now if they support your car or charger. I have it. You get cheap overnight power, but they ask you to plug your car in all the time when it's at home, and they will charge it whenever there's an excess at the low overnight price, even if it's during the day.
There's also Agile Octopus which gives you a variable price for all your power at any time of the day or night. So you can set your water heater or washing machine to run whenever it's cheap, not just overnight.
Ours used to be called something less sexy like "Economy 5+1". Essentially Economy 7, but trading a couple of the overnight hours for an hour mid afternoon to top the HW and radiators up.
Wasn't even 'smart', they just triggered it via the same system that triggers ecomomy 7 meters.
Wind turbine generation combined with pump storage has been in operation for several years at the Glendoe development just south of Fort Augustus. The turbines are away out at 600m beside a purpose built reservoir, connected to a generation and pumping facility on the shore of Loch Ness. There's another one in planning as well, east of Foyers and also making use of Loch Ness.
This is nothing new; Foyers has been operating to 'store' excess overnight (gas & oil, Peterhead) generation uphill for well over 40 years. But Glendoe is the first properly integrated and significant sized development so far. We could do a lot more of this in Scotland, there are plenty of suitable locations for joined up generation & storage to work.
I’m just amused that there’s a loch called Lochy. Is its last name McLochFace?
Just wait til you find the eponymous Loch Loch.
I thought National grid were suppose to prioritise renewables? ie buy as much as they can get and reduce Gas or coal instead?
Even with all renewable sources at max output, it still wouldn't be enough to meet demand at the moment. So they should not be stopped for 'lack of demand'.
We could do a lot more of this in Scotland, there are plenty of suitable locations for joined up generation & storage to work.
Yeah, why not, I've already given up on the idea that any of the Highlands is going to continue to look anything like wild land. Is there any hill in Scotland you can't see a wind turbine from on a reasonably clear day?
Very little of the Highlands is genuinely wild land; most of it is in effect an industrial landscape, having been managed to look a particular way to suit the interests of sporting estates exclusively and is maintained that way by an excess of unproductive sheep and malnourished deer.. Barren heather hillsides are no more natural here than a forest of wind turbines would be. Most of it should be temperate rain forest, if not active in food production. Look in any peat bog at 600m and it's full of ancient tree stumps and roots.
Even with all renewable sources at max output, it still wouldn’t be enough to meet demand at the moment. So they should not be stopped for ‘lack of demand’.
That depends, you have your grid anchors which will be thermal power stations and they are absolutely not going to be turned off.
Well, it would surely be possible to replace gas with nuclear, if not more renewables. Offshore wind is pretty consistent. It's very rare to have a completely calm day around the entire UK coastline. I certainly think there is scope for more generation from renewables. The electricity industry agrees - a vast amount of investment is going in to huge offshore wind projects.
That's not to mention the potential for tidal schemes which would at least benefit their local community.
There are 32 Gas-powered power stations in the UK. A lot are just 1GW or less. More renewable capacity would allow some to be retired.
The lack of inertia for frequency control is an issue with non-synchronous plant (asynchronous, DFIG, fully converted).
You can compensate with batteries and other interesting kit but better / easier to have some heavy synchronous plant with a decent governor droop curve.
Of course there are those asking exactly what bad things really happen if we open the frequency limits a bit - ‘cos it’d be a sight cheaper if we did.
In response to the OP, here is a paper on different turbine-generator-grid interfaces. Good luck.
https://www.researchgate.net/publication/268395758_GENERATOR_TECHNOLOGY_FOR_WIND_TURBINES_TRENDS_IN_APPLICATION_AND_PRODUCTION_IN_CROATIA_Invited_paper#pf5
Well, it would surely be possible to replace gas with nuclear, if not more renewables.
Still need gas for emergencies (nuclear needs an external source of power to start) but yes.
Its a question of space. We have 4 hours or so worth of UK consumption from pump storage IIRC. We have nowhere to build a lot more.
I investigated almost every slate quarry in North Wales for pumped hydron including the Glyn rhonwy one that still seems to be a thing.
Is that Glyn Rhonwy project still going? I first found out about it absolutely ages ago so assumed it had gone nowhere, but I see now it's still not actually gone anywhere but has doubled in size...
Most power stations need electricity to start them. Technically speaking, a bloke with a land Rover at Cruachan Hydro Power station can drive up to the dam, manually open the sluices to start Cruachan turbines, which then feed leccy to other stations to fire up the UK grid. Not sure if other hydro schemes can do that but Cruachan was developed with the connectivity / infrastructure to do so.
Cruachan can but its a one shot affair and needs to feed to Peterhead as there are no other thermal stations in our section of the grid.
Torness needs something in the order of 21MW just to run its gas circulators (on one reactor) never mind its coolant water pumps and myriad safety systems. By comparison a gas station could probably start itself with some suitably sized diesel generators.