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  • FIRST POST
    • GreatApe
    • By GreatApe 10th Aug 19, 7:41 AM
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    GreatApe
    First blackout of the wind power heavy system
    • #1
    • 10th Aug 19, 7:41 AM
    First blackout of the wind power heavy system 10th Aug 19 at 7:41 AM
    So it seems a power station tripped and some wind turbines went offline

    This is not abnormal, However what was abnormal is that we had only a few CCGTs in the system yesterday due to high wind output

    If you have 5GW CCGT in the system that's not a lot of inertia so if 1GW goes offline you lose 20%+. If it was low wind and there was 20GW CCGT in the system that same 1GW would be only 5% and wouldn't have caused the frequency to dip so much

    So anyone want to cost yesterday's blackout in �� and misery thanks to a wind heavy system which is not forced to have backup battery and hence weaken security of supply?

    Wind farms and PV farms should be forced to have big batteries else they are freeloading

    Also right now the grid really doesn't like going below 5GW so installing more wind just results in less clean imports rather than displacing CCGTs further. So to integrate more renewables is going to need large batteries perhaps as much as 4GW+ of batteries to support frequency control.

    Another hidden cost

    https://theenergyst.com/national-grid-two-generators-cause-big-frequency-drop/
    Last edited by GreatApe; 10-08-2019 at 7:48 AM.
Page 7
    • Hexane
    • By Hexane 16th Aug 19, 12:37 PM
    • 79 Posts
    • 111 Thanks
    Hexane
    Although the biggest reported impact was on rail transport, not much seemed to be made about what seemed to be inordinate delays in getting the rail network up and running again (although this was touched on). Most power-critical organisations have well developed plans to deal with power outtages, and although I can see that you can hardly have a backup generator to run a few dozen trains, it did seem that there were some big gaps in the contingency planning for the rail network. If it was me, I'd be shining the same spotlight on the rail network as I was shining on National Grid.
    Originally posted by mmmmikey
    Indeed. It seems that at least some of the worse-than-expected impact on rail services was due to almost brand new German-manufactured electric trains that can't be restarted once they've had a power failure, meaning a technician has to drive out to them to fix them. The wonders of modern technology... https://www.bbc.co.uk/news/uk-49302996
    7.25 kWp PV system (4.1kW WSW & 3.15kW ENE), Solis inverter, myenergi eddi & harvi for energy diversion to immersion heater. myenergi hub for Virtual Power Plant demand-side response trial.
    • GreatApe
    • By GreatApe 16th Aug 19, 12:46 PM
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    GreatApe
    https://www.drax.com/energy-policy/need-whole-country-frequency/

    Written two years ago but explans the problem well

    1. Coal and gas power stations have inertia which dampen frequency changes

    2. They can respond within about 1 second (drax says their coal units within half a second) to increase or decrease output

    3. Wind and solar don't have inertia not useable inertia

    4. As wind and solar go up the need for more synthetic inertia and frequency control gets more important
    • JKenH
    • By JKenH 16th Aug 19, 1:06 PM
    • 565 Posts
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    JKenH

    Just for fun, before the government decided to kill off domestic PV subsidies of 4p/kWh this year, they had originally expected them to be 20.7p/kWh, and there's more, that's in 2011 monies, and we don't want to sell you just that, let's throw in the fact they were then 25 not 20 yrs, so roughly 4p v's an expected 32p (not exact, but I think a close guess).

    Nobody, certainly not me, expected RE costs to fall so fast.
    Originally posted by Martyn1981
    How much have domestic PV prices fallen since 2011, assuming they are about 1000 per kwp now? Not as fast as the FiT?
    Northern Lincolnshire. 7.8 kWp system, (4.2 kw west facing panels , 3.6 kw east facing), Solis inverters, Solar IBoost water heater, Mitsubishi SRK35ZS-S and SRK20ZS-S Wall Mounted Inverter Heat Pumps
    • mmmmikey
    • By mmmmikey 16th Aug 19, 3:06 PM
    • 278 Posts
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    mmmmikey
    https://www.drax.com/energy-policy/need-whole-country-frequency/

    Written two years ago but explans the problem well
    Originally posted by GreatApe
    Yes, well worth a read, and also worth following the various embeded links. This article explains what they've done in Quebec to mitigate the issue, I wonder if we'll end up doing much the same in the UK?

    https://spectrum.ieee.org/energywise/energy/renewables/can-synthetic-inertia-stabilize-power-grids
    • zeupater
    • By zeupater 16th Aug 19, 3:48 PM
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    zeupater
    Yes, well worth a read, and also worth following the various embeded links. This article explains what they've done in Quebec to mitigate the issue, I wonder if we'll end up doing much the same in the UK?

    https://spectrum.ieee.org/energywise/energy/renewables/can-synthetic-inertia-stabilize-power-grids
    Originally posted by mmmmikey
    Hi

    ... but doesn't that effectively say that the IEEE would deem that a collection of large wind turbines acting together actually has a level of rotational inertia which would collectively equate to that of a conventional power station and that this inertia can be tapped to help maintain frequency when there's an outage elsewhere, the effect of which had already been established after analysing an example of this happening?! ...

    ... maybe, after reading that, the future doesn't seem quite as bleak as we're sometimes led to believe ... Kinetic energy, momentum and rotational inertia in spinning mass, who'd have thought it, isn't science wonderful! ....

    HTH
    Z
    Last edited by zeupater; 16-08-2019 at 3:51 PM.
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 16th Aug 19, 3:49 PM
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    Martyn1981
    How much have domestic PV prices fallen since 2011, assuming they are about 1000 per kwp now? Not as fast as the FiT?
    Originally posted by JKenH
    No not as fast as you say, but 4p(ish) was at least helpful, I'd suggest 7p would have kept install rates high*. But we shouldn't compare prices directly to the FiT as there are also other income streams, the leccy savings and the export payments. For simplicity if they provided 50% of the income, then a 50% drop in PV install costs would warrant a 100% drop in the FiT IYSWIM.

    *When the government cut the FiT right down to about 5p, they also set maximum quarterly install limits, which were very low.

    The difficulty is in deciding what level of subsidy (for anything) is fair and reasonable. To promote a product, no subsidy is really needed, but to promote a desired change such as a shift to RE, and away from FF's and to meet targets, even international fines, then it all gets a bit more complicated.

    Also, where does the money go. Should we pay subsidies to households and small businesses, out of levies on households and small businesses, or give it all to China and France as the principal investors in HPC? What about jobs, such as the UK's solar industry, etc etc.. It all gets too complex.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • mmmmikey
    • By mmmmikey 16th Aug 19, 4:04 PM
    • 278 Posts
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    mmmmikey
    Hi

    ... but doesn't that effectively say that the IEEE would deem that a collection of large wind turbines acting together actually has a level of rotational inertia which would collectively equate to that of a conventional power station and that this inertia can be tapped to help maintain frequency when there's an outage elsewhere, the effect of which had already been established after analysing an example of this happening?! ...

    ... maybe, after reading that, the future doesn't seem quite as bleak as we're sometimes led to believe ... Kinetic energy, momentum and rotational inertia in spinning mass, who'd have thought it, isn't science wonderful! ....

    HTH
    Z
    Originally posted by zeupater
    I don't think that's quite what it says. My understanding is that the inertia described here is synthetic - i.e. additonal software, controls and other engineering are making the wind turbines generate power in a manner in which they exhibit an inertia like effect and seem to behave like conventional gas / coal turbines. The point being that the industry regulator had to legislate to ensure that the wind installations are designed like this, because otherwise there is a potential problem (which may or may not be part of the issue we had last week).

    "In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."

    I definitely agree that the future is rosy as far as wind power is concerned, but only if we avoid complacency and make sure that as we scale up we recognise the additional challenges that creates and reflect those challenges in the design.
    • zeupater
    • By zeupater 16th Aug 19, 4:18 PM
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    zeupater
    I don't think that's quite what it says. My understanding is that the inertia described here is synthetic - i.e. additonal software, controls and other engineering are making the wind turbines generate power in a manner in which they exhibit an inertia like effect and seem to behave like conventional gas / coal turbines. The point being that the industry regulator had to legislate to ensure that the wind installations are designed like this, because otherwise there is a potential problem (which may or may not be part of the issue we had last week).

    "In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."

    I definitely agree that the future is rosy as far as wind power is concerned, but only if we avoid complacency and make sure that as we scale up we recognise the additional challenges that creates and reflect those challenges in the design.
    Originally posted by mmmmikey
    Hi

    What I read in the article which seemed to address the issue was ...
    To emulate the inertial behavior of massive rotating equipment, a renewable generator must somehow find extra power quick. Qu!bec's wind turbines do so through a collaboration between the turbines' solid-state power electronics and their moving parts. "When the wind turbines see an imbalance between load and generation that causes a frequency deviation on the system they’re able to … extract some kinetic energy that is stored in the rotating masses of the wind turbines,”
    ... looks pretty relevant, but then again, those turbines may be old & the latest ones being installed nowadays may be less advanced ... ... in which case lessons will be learned!

    HTH
    Z
    Last edited by zeupater; 16-08-2019 at 4:21 PM.
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • mmmmikey
    • By mmmmikey 16th Aug 19, 7:13 PM
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    mmmmikey
    ... looks pretty relevant, but then again, those turbines may be old & the latest ones being installed nowadays may be less advanced ...
    Originally posted by zeupater
    Whoops, thanks, yes, I've realised that the inference that we have the "older non-syntehtic inertia" type in the UK was in another article, not the one I linked to, my mistake. It will be interesting to see what the Ofgem report has to say.

    I know from the news that National Grid are submitting their initial report to Ofgem today - do you know if that report will hit the public domain or will we have to wait for the Ofgem report?


    Thanks, Mike
    • Martyn1981
    • By Martyn1981 17th Aug 19, 7:18 AM
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    Martyn1981
    "In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."
    Originally posted by mmmmikey
    Only pondering out loud, but the 2005-2011 WT's will be much smaller than the monsters we now have, so I assume greater rotational inertia per WT, though of course less WT's.

    Also, I think (and by I think, I mean scratching the bottom of my memory) but WT's performance can be altered by choosing the size of the generator. So a smaller unit, will give a higher capacity factor*, at the price perhaps of a bit less annual generation, but would (here's the guess part) also improve rotational inertia for that generator, though again with the caveat that it will be a slightly smaller generator.

    *Same base design, only the rating changes, say from 9MW to 8.5MW, perhaps for that higher cf, or because the location has more variable winds, and there's a need to 'mine' the lower wind speeds etc etc..
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • mmmmikey
    • By mmmmikey 17th Aug 19, 8:47 AM
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    mmmmikey
    Only pondering out loud, but the 2005-2011 WT's will be much smaller than the monsters we now have, so I assume greater rotational inertia per WT, though of course less WT's.
    Originally posted by Martyn1981

    Again, scratching my head and remebering back to O-Level physics ( which was some time ago now ) then I think the speed of rotation is more siginificant than the mass here - i.e. gas generators spin at 3000 rpm whereas wind turbines turn at a fraction of that speed.


    Edit: so shouldn't we be discussing momentum as well as inertia? One for the scientists.....
    Last edited by mmmmikey; Yesterday at 9:00 AM.
    • Martyn1981
    • By Martyn1981 17th Aug 19, 11:58 AM
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    Martyn1981
    Again, scratching my head and remebering back to O-Level physics ( which was some time ago now ) then I think the speed of rotation is more siginificant than the mass here - i.e. gas generators spin at 3000 rpm whereas wind turbines turn at a fraction of that speed.


    Edit: so shouldn't we be discussing momentum as well as inertia? One for the scientists.....
    Originally posted by mmmmikey
    Not a clue mate, not a clue! We exceeded my pay grade several posts ago.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 17th Aug 19, 12:00 PM
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    zeupater
    Again, scratching my head and remebering back to O-Level physics ( which was some time ago now ) then I think the speed of rotation is more siginificant than the mass here - i.e. gas generators spin at 3000 rpm whereas wind turbines turn at a fraction of that speed.


    Edit: so shouldn't we be discussing momentum as well as inertia? One for the scientists.....
    Originally posted by mmmmikey
    Hi

    As none of the plethora of alleged scientists have yet responded, you'll probably find that Ek=1/2mv2 would probably do the job ...

    Kinetic energy is the key and as you observed, velocity is relatively more important when doubled - however, what needs to be considered is that the radius of the spinning element in a gas generator weighing Xkg is far less than that of the blades in a wind turbine weighing Y tonnes. Additionally, rpm is effectively meaningless when comparing the energy available in the two technologies, it's simply the relative energy of the mass in motion, so a large mass rotating slowly in a large radius can easily store more kinetic energy than a small mass rotating quickly in a small radius ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 17th Aug 19, 12:20 PM
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    • 13,830 Thanks
    Martyn1981
    Hi

    As none of the plethora of alleged scientists have yet responded, you'll probably find that Ek=1/2mv2 would probably do the job ...

    Kinetic energy is the key and as you observed, velocity is relatively more important when doubled - however, what needs to be considered is that the radius of the spinning element in a gas generator weighing Xkg is far less than that of the blades in a wind turbine weighing Y tonnes. Additionally, rpm is effectively meaningless when comparing the energy available in the two technologies, it's simply the relative energy of the mass in motion, so a large mass rotating slowly in a large radius can easily store more kinetic energy than a small mass rotating quickly in a small radius ...

    HTH
    Z
    Originally posted by zeupater
    So, in short, a 12MW WT with 165 tonnes of blade, and 60 tonnes of hub spinning round would take more than just me, a long pole and a net to stop?
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 17th Aug 19, 1:12 PM
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    zeupater
    So, in short, a 12MW WT with 165 tonnes of blade, and 60 tonnes of hub spinning round would take more than just me, a long pole and a net to stop?
    Originally posted by Martyn1981
    Hi

    Ever seen a trebuchet throw a car? ... you'd have acceleration to 200mph that would make a F1 car look like a snail ...

    It's really the management of this kinetic energy that can allow the turbines to provide a short boost to the grid through providing more energy than would be normal to maintain rotation at a particular demand loading .... effectively overclocking the turbines for a while in the acceptance that tapping into the stored kinetic energy will act as a brake to slow the velocity over time, but better this to buy time for other assets to be brought on line than suffer a major frequency drop issue before those assets can react.

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • GreatApe
    • By GreatApe 17th Aug 19, 3:18 PM
    • 3,500 Posts
    • 2,646 Thanks
    GreatApe
    Hi

    Ever seen a trebuchet throw a car? ... you'd have acceleration to 200mph that would make a F1 car look like a snail ...

    It's really the management of this kinetic energy that can allow the turbines to provide a short boost to the grid through providing more energy than would be normal to maintain rotation at a particular demand loading .... effectively overclocking the turbines for a while in the acceptance that tapping into the stored kinetic energy will act as a brake to slow the velocity over time, but better this to buy time for other assets to be brought on line than suffer a major frequency drop issue before those assets can react.

    HTH
    Z
    Originally posted by zeupater



    As per common sense if you did this in a wind heavy system for anything other than a very short burst you'd screw yourself

    You'd get a boost for a few seconds, the result being reducing the speed of the turbine blades so that after those few seconds the turbine itself now produces less energy

    So you might have a wind turbine generating 10MW, you draw 15MW from it for 20 seconds but now when you let it be it's generating only 5MW as it has slowed down

    Not a good solution
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