Any thoughts/information on what happened? Was it a lack of spinning reserve?
Was it " The Portuguese operator, REN, said the outage was caused by a “rare atmospheric phenomenon”, with extreme temperature variations in Spain causing “anomalous oscillations” in very high-voltage lines."
as is written in the Guardian?
The Italien blackout from a few years ago had a definate cause in the tripping of interconnetors from Switzerland during a storm.
The next report from ENTSO-E on the Iberian blackout has now been published:
This suggests that the cause was a large quantity of various renewables going off line.
'Several important generation trips occurred from 12:32:00 onwards. Between 12:32:00.000 and 12:32:57.000, there was a loss of 208MW identified distributed wind and solar generators in northern and southern Spain, as well as an increase in net load in the distribution grids of approximately 317MW, which might be due to the disconnection of small embedded generators <1MW (mainly rooftop PV) or to an actual increase in load or to a combination of both. The reasons for these events are not known. From 12:32:57.000 until 12:33:18.020, major disconnection events occurred in the regions of Granada, Badajoz, Sevilla, Segovia, Huelva, and Cáceres, which resulted in an additional loss of generation of at least 2GW (the effects of frequency deviation suggest a loss of even 2.2GW).'
The reasons for for the trips are not stated.
There seems to be a general agreement that to just keep adding inverted coupled equipment to a conventional grid is not going to work and will result in various stability problems.
There are certainly technical solutions available, but are they viable? If you are starting from scratch or from a very small area system there are usable solutions. If you have ‘Ball and Chain Historical Infrastructure’ (I like that phrase) then it is rather more difficult. How much time , money and resources would you have to invest to upgrade a 50 or 60Hz grid to remain stable under rapidly varying renewable feeds? Would you ever get a payback? It is often quoted that the energy payback for wind turbines is around 1 year and solar PV 2 years. This is at the connection point. If you have to add batteries, pumped storage, hydrogen systems, new grid segments, DC links, synchronous capacitors etc. would there be any payback on energy, resources or financially?
Another Ball and Chain Historical Infrastructure problem is the British Railway loading gauge. Britain was the first and started out with the smallest. Now this places significant restrictions on what can be carried on British tracks. Could the loading gauge be enlarged? Technically yes, practically no.
UK railways are a bad example - there is not one historical loading gauge for a start but many historical ones.
But, starting with the most heavily used routes, there is a concerted programme of raising bridges and widening tunnels to allow modern container traffic, (increasing to the euro W12 gauge is usually preferred) and enough height to permit overhead electrification with pantographs. It will however take decades, and probably like electrification, which has been on-going now for over a century and is not even 40% of the network track length, will falter on the hard bits.
Mike.
There are certainly technical solutions available, but are they viable? If you are starting from scratch or from a very small area system there are usable solutions. If you have ‘Ball and Chain Historical Infrastructure’ (I like that phrase) then it is rather more difficult. How much time , money and resources would you have to invest to upgrade a 50 or 60Hz grid to remain stable under rapidly varying renewable feeds? Would you ever get a payback? It is often quoted that the energy payback for wind turbines is around 1 year and solar PV 2 years. This is at the connection point. If you have to add batteries, pumped storage, hydrogen systems, new grid segments, DC links, synchronous capacitors etc. would there be any payback on energy, resources or financially?
We will need batteries. The good news is that they keep coming down in price. Once you have them, they aren't just a backup in case there's no wind and no sun. They can be used every day for peak supply clipping by charging them up whenever electricity wholesale prices are lowest.
In my experience the loading gauge is the least of our problems in UK railways! In 30 years plus in the industry I've never known it come up as an issue - falls well into the "nice to have". Personally I suspect that getting ERTMS properly rolled out would be a much more practicable solution to the immediate capacity problems. Which has taken 25 years so far...
the good news is that we have over 5GW of batteries connected to the GB system, plus all the Tesla power walls hiding behind the meter. There's a lot a more in the pipeline. yes, they're used to clip the peaks. they're also used to stabilise the system by responding to the frequency: the classical relationship between power and frequency still holds true
The rail gauge analogy isn't the right one. The wires aren't being changed. It's the signalling that's being upgraded as the steam engines are being phased out, and newer faster trains, with digital controls are being introduced... Let's not take the analogy too far.
a general agreement that to just keep adding inverted coupled equipment to a conventional grid is not going to work and will result in various stability problems.
I feel this is the 'Luddite' problem of not appreciating where the changes come from. When, by mandate, inverter coupled equipment is neutered as simply negative load (grid following), rather than being generational power that will support the grid, then these major grid trips will continue to happen. Yesterday's status quo was a worthwhile reference, but is not a vision for the future.
There are plenty of ways of creating grid forming 'inverter' based designs that don't have to depend on e.g. hand drawn Nichols charts and computer simulations based old analog approaches and equations.
The missing element in the discussion is the 'short term' storage of energy, and the confusion about the purpose of "Inertia" and various "Compensators". Once the system is far more 'electronic' (and with batteries;-) in its response characteristics, it will be the switch gear trip settings that will need to be addressed (as it always was).
Older simulations/models almost always fail when new technologies arrive because they have no way of integrating the new capability into the old capability approach. There are apocryphal stories of a kangaroo counting simulation firing the default beach ball weapon back at the approaching counting helicopter because they'd simply reskinned a war game simulation. Or the war games that showed that InfraRed technology had no effect on night fighting because the simulation didn't cover/allow time of night effects. Lots of hidden implementation details catching folks out.
We are seeing the same in power system design where simulations & models, essentially are not yet fit for the disruptive nature of CO2 reduction and the renewables replacement. There are still plenty of hidden issues in power systems, such as the use of 'pu' (per unit; and it's rationale), phase jumps, etc.
There's also the V/f transformer saturation limitations.
Which 'classical' frequency - power relationship were you thinking (i.e. wondering about hidden assumptions that bring frequency into the I.ac * V.ac = P.ac ?)
the classical relationship that a power shortfall leads to a drop in frequency, which can be corrected by injecting more power into the system. it's how both steam turbine governors and modern frequency-responsive battery systems work: there are smarter engineers than me out there, who can successfully integrate the old and the new
Thanks; That, for me, is the flywheel temporary energy storage of the rotating inertia.
It also shows how we can easily leap past an 'obvious' issue in discussions that can become 'untrue' when there's a technology update. We only get rotation rate drops because we were using rotation based temporary energy storage. If we aren't using rotation based energy storage we don't (automatically) get a drop in frequency.
We can also fall into the frequency-phase trap where it's unclear where we have set the reference, both locally and globally, such as : "Are we still maintaining electric synchronous clocks to the level that we used to, given most have been phased out". Locally (to a generator), we talk of both frequency changes, and phase changes, in the same discussion not realising the confusion.
We can know the destination frequency/phase before we generate, now that most lines have optic fibre incorporated (Synaptec..).
Thanks again for clarifying.
There seems to be a general agreement that to just keep adding inverted coupled equipment to a conventional grid is not going to work and will result in various stability problems.
There are certainly technical solutions available, but are they viable?
Well if you look at the GB system, NESO are procuring stability services, to provide rotating inertia and short-circuit current contribution, services which previously would have only been available from conventional generation while it was running to generate active power. These services are now being provided, typically, from synchronous condensers (i.e, conventional generators connected to rotating mass, such as flywheels) which operate without generating active power, so the stability service is now split from, and independent of, the provision of active power so you can have the stability service without running coal/gas generation, so avoiding the need to curtail renewables in order to run conventional generation for stability purposes.
There's already a number of assets providing these stability services and they have been in operation for some years now.
In parallel, there's also been a number of new frequency response type services developed to take advantage of the very fast response times of battery assets, to help manage grid frequency. I think the first one was the Enhanced Frequency Response (EFR) service some years ago, where response times were sub-1 second. There's a new suite of Dynamic services which are being introduced geared around batteries and fast responding technologies.
Going back a few years, NESO was expecting it would be able to operate the grid with 100% green energy for periods of time around 2025 onwards, presumably through a combination of these new stability and frequency services but possibly benefitting from some conventional generation (nuclear). I'm not sure about the current status of this target, but they've been putting in place the building blocks to get there.
Another Ball and Chain Historical Infrastructure problem is the British Railway loading gauge. Britain was the first and started out with the smallest. Now this places significant restrictions on what can be carried on British tracks. Could the loading gauge be enlarged? Technically yes, practically no.
Another example, closer to home, is Britain's electricity system, which itself developed in a non-standardised way with a mixture of DC systems, AC systems using a range of different frequencies, distributed at numerous different voltages. Britain was slow to standardise the electricity system, but it got there in the end, first with the standardisation of frequency at 50Hz AC as part of the development of the National Grid, which required the replacement of significant amounts of non-50Hz equipment, particularly the large 40Hz system in the North East. Then various, more localised measures, to standardise distribution to AC and to 230V over following decades.
If there's enough benefit, then eventually it happens. Or, people innovate to live with the constraints.
There seems to be a general agreement that to just keep adding inverted coupled equipment to a conventional grid is not going to work and will result in various stability problems.
There are certainly technical solutions available, but are they viable?
Well if you look at the GB system, NESO are procuring stability services, to provide rotating inertia and short-circuit current contribution, services which previously would have only been available from conventional generation while it was running to generate active power. These services are now being provided, typically, from synchronous condensers (i.e, conventional generators connected to rotating mass, such as flywheels) which operate without generating active power, so the stability service is now split from, and independent of, the provision of active power so you can have the stability service without running coal/gas generation, so avoiding the need to curtail renewables in order to run conventional generation for stability purposes.
There's already a number of assets providing these stability services and they have been in operation for some years now.
In parallel, there's also been a number of new frequency response type services developed to take advantage of the very fast response times of battery assets, to help manage grid frequency. I think the first one was the Enhanced Frequency Response (EFR) service some years ago, where response times were sub-1 second. There's a new suite of Dynamic services which are being introduced geared around batteries and fast responding technologies.
Going back a few years, NESO was expecting it would be able to operate the grid with 100% green energy for periods of time around 2025 onwards, presumably through a combination of these new stability and frequency services but possibly benefitting from some conventional generation (nuclear). I'm not sure about the current status of this target, but they've been putting in place the building blocks to get there.
Another Ball and Chain Historical Infrastructure problem is the British Railway loading gauge. Britain was the first and started out with the smallest. Now this places significant restrictions on what can be carried on British tracks. Could the loading gauge be enlarged? Technically yes, practically no.
Another example, closer to home, is Britain's electricity system, which itself developed in a non-standardised way with a mixture of DC systems, AC systems using a range of different frequencies, distributed at numerous different voltages. Britain was slow to standardise the electricity system, but it got there in the end, first with the standardisation of frequency at 50Hz AC as part of the development of the National Grid, which required the replacement of significant amounts of non-50Hz equipment, particularly the large 40Hz system in the North East. Then various, more localised measures, to standardise distribution to AC and to 230V over following decades.
If there's enough benefit, then eventually it happens. Or, people innovate to live with the constraints.
thanks, that's a useful expansion
being pedantic, synchronous condensers are there to control reactive power
that doesn't detract from your point about NESO procuring some big flywheels, as proposed in previous posts. I don't have the figures to hand but, at least in terms of GW connected, I think that NESO are procuring much more battery capacity than flywheels
it feels like NESO are on top of this:
a) make sure that there are enough big flywheels connected to smooth things out a bit and to preserve the classical frequency - power relationship
b) procure enough responsive generation to keep the frequency within 2% of target, to cater for credible loss of in-/out-feed
c) look to the distributors to shed load if the frequency falls below that 2% threshold, to save the wider system
that point about condensers and flywheels brings us neatly back to the original post. while the final report is yet to emerge, it looks like the issue on the Iberian Peninsula was cascade tripping on over-voltage rather than any kind of imbalance between production and consumption
being pedantic, synchronous condensers are there to control reactive power
that doesn't detract from your point about NESO procuring some big flywheels, as proposed in previous posts.
Those flywheels are synchronous condensers. The synchronous condensers had traditionally been used primarily to provide reactive power control, but because they're a spinning mass they also provide inertia and being connected to a conventional, synchronous generator they also provide short-circuit fault current contribution - with these stability services being in demand now, with the shift toward inverter-based renewable generation.
I refer you to ENTSO-E:
https://www.entsoe.eu//technopedia/techsheets/synchronous-condenser/
Example project, installing a synchronous condenser for inertia and stability purposes:
new.abb.com/.../abb-synchronous-condensers-go-live-in-liverpool-to-stabilize-the-uks-power-grid
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