Is the National Grid sufficiently resilient?

yorksrob said:

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Fair point. I suppose the last one was around a decade ago.

Do we trust the next one to be though !

The bigger picture is how do we incentivise the grid, to ensure that the lights remain on !

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We were 'incentivising' generators through the Capacity Market, which was blocked by the EC as illegal state aid. The loss of that income probably contributed to a few GW of coal capacity being shut down ahead of plans. The question is really do we trust the government to come up with 'innovative' contracting mechanisms that are not terrible in every way? If the government (or the system operator) had wanted a particular kind of new plant like pumped storage of CCGTs, they had plenty of legal avenues available to get one of those built. Instead they came up with a convoluted 'market-based' solution that propped up a few existing coal units and led to a load of new diesel generators being bought but no real long-term solutions, and in the end the whole thing wasn't compliant with competition law and got shut down unexpectedly. The electricity industry often makes rail look like a model of sensible long-term planning and well-informed government engagement...

AM9 said:

I'm not sure what you mean by incentivise?

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Extract fines if they don't ?

Or just make it the company ethos - "Keeping the lights on".

It seemed to inspire previous generations .

yorksrob said:

Extract fines if they don't ?

Or just make it the company ethos - "Keeping the lights on".

It seemed to inspire previous generations .

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except that they had a public service remit. How many times to we have to repeat that the directors of UK private businesses are legally required to act in the interests [only] of the shareholders? Always obeying the law, of course!

Does anyone know whether Dinorwig was used on Friday? It is a pumped storage scheme commissioned in 1984 but still (as far as I know) operational. It has 6 x 300MW turbine/pumps and was intended to allow CEGB (remember them?) to iron out peak loads and cope with the sudden loss of 500MW coal fired sets. With the upper reservoir full, the turbines are kept empty and spinning but off-load. It can be brought from zero to full output in 16s.

Intellectual98 said:

You are a huge bundle of negativity, but haven't provided much in the way of other solutions. Pumped hydro is great, but not a long term solution, there's not enough glens in Scotland even if we filled them all, and I'm pretty sure there will be some losses in the 300 miles to get the leccy back to London.

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First you either need large synchronous generator equipped generating capacity, or you need synchronous condensers or static voltage support systems for the sub second range.
Then Pumped Hydro for rapid response in the seconds-to-minutes range, then a combination of pumped hydro capacity and fast response gas plants to produce ultimate backup to ensure the grid stays up.

And losses in 300 miles is negligible at high voltage.
We have technology for 1000-1200kV transmission lines available if required where the losses from Caithness to Penzance would be less than the losses between the substation and the consumer.

Also Welsh Valleys and potentially that Gravity Storage thing.

EDIT:

I'm afraid the current Thatcherite model, which is also required by the EU, of a "free market" in electricity generation and transmission will never yield a reliable grid over the long term.

They are just too incentivised to cut corners to save money for the shareholders.

The only model that has been shown to work and deliver the electricity production increases needed for decarbonisation is the traditional unitary electricity supplier model. (The CEGB/Regional Electricity boards were de-facto one supplier)

The state should use its very long term, very low cost borrowing capability to buy sufficient generating plant and transmission assets to meet demand in a sufficiently reliable way.

In a post carbon future any interruption in the transmission system is unacceptable. It could easily kill thousands of people if it occurs in midwinter.

The system also has to be fair for consumers, be cheap for consumers and be simple to understand for consumers.
For example, all charges, with explanation, for all interactions a consumer might have with Hydro Quebec are detailed in a single document that only runs to 180 large print pages, with a compact chart that only runs to 3.

DerekC said:

Does anyone know whether Dinorwig was used on Friday? It is a pumped storage scheme commissioned in 1984 but still (as far as I know) operational. It has 6 x 300MW turbine/pumps and was intended to allow CEGB (remember them?) to iron out peak loads and cope with the sudden loss of 500MW coal fired sets. With the upper reservoir full, the turbines are kept empty and spinning but off-load. It can be brought from zero to full output in 16s.

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Yes Dinorwic did what is was supposed to do and rapidly picked up the lost load but at the same time there was automatic disconnection of certain grid points to protect the system from cascade failure and total blackout. The real issue on Friday is at the point of failure 50% of generation was not hard connected to the grid as wind/solar/interconnectors are connected via power electronics so don't have the stored mechanical energy that a steam powered 660MW set has known as system inertia. As a result when generation was lost the frequency fell faster than would have been the case when generation was 100% steam turbines. Historically the inertia of all these turbines would have give a few seconds of delay (huge amount of time in a power system) to allow Dinorwic to rapidly ramp up to full load.

Nicholas Lewis said:

As a result when generation was lost the frequency fell faster than would have been the case when generation was 100% steam turbines. Historically the inertia of all these turbines would have give a few seconds of delay (huge amount of time in a power system) to allow Dinorwic to rapidly ramp up to full load.

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Strictly speaking it does not have to be a steam turbine as such, just a synchronous generator of some description that is directly coupled to the power line.
Hydro generators, gas turbines and steam turbines, or even free spinning units can do this.

Or indeed ABBs very high voltage high power synchronous motors in industrial facilities.

Perhaps we need a national flywheel to maintain a bit more stability.

Roast Veg said:

Perhaps we need a national flywheel to maintain a bit more stability.

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Rather than wasting power (and considerable hardware costs) in just spinning a flywheel, a better solution might be to connect some of the larger solar and wind farms through rotary synchronisation methods as well as the power inverter/synchronisers.

AM9 said:

Rather than wasting power (and considerable hardware costs) in just spinning a flywheel, a better solution might be to connect some of the larger solar and wind farms through rotary synchronisation methods as well as the power inverter/synchronisers.

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Are you suggesting connecting solar farm DC output to a motor to turn an AC generator?
There would be pros and cons....

Kingspanner said:

Are you suggesting connecting solar farm DC output to a motor to turn an AC generator?
There would be pros and cons....

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Not necessarily but there are some renewable sources that are not run synchronous with the national grid, their interconnect being by running static inverters. Were they fed through a 'motor generator' connection, that could provide some short-term stability to the net frequency.
Standing back a bit from the current panic of last friday's problem, I think that this is a teething problem of the transition away from predominately rotary electromagnetic energy production to a largely static inverter system. Eventually, the only rotary sources will be Nuclear and Hydro with 'as required' pumped storage hydro to carry over short-term peaks. I also think that despite the current complaints of wildlife interests, there will be a couple of very large-scale tidal hydro-generator schemes built. They have a high capital cost but relatively low running expenses and unless the world stops spinning, will provide a significant part of the base load supply.

AM9 said:

Not necessarily but there are some renewable sources that are not run synchronous with the national grid, their interconnect being by running static inverters. Were they fed through a 'motor generator' connection, that could provide some short-term stability to the net frequency.
Standing back a bit from the current panic of last friday's problem, I think that this is a teething problem of the transition away from predominately rotary electromagnetic energy production to a largely static inverter system. Eventually, the only rotary sources will be Nuclear and Hydro with 'as required' pumped storage hydro to carry over short-term peaks. I also think that despite the current complaints of wildlife interests, there will be a couple of very large-scale tidal hydro-generator schemes built. They have a high capital cost but relatively low running expenses and unless the world stops spinning, will provide a significant part of the base load supply.

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Pretty sure a motor generator would be more expensive and have larger losses than simply having the power electronics connected in parallel to a synchronous condenser on the AC side.
The DC motor will either need a full-power inverter or an expensive to maintain commutator anyway, so you gain very little compared to simply having a hydrogen cooled synchronous condenser.

Supposedly the cost of synchronous condensers is only about $40-90/kVA, which is negligible in a grid system, unless you are a private sector operator that is incentivised to cut corners.

Also worth noting that whilst nuclear generators have very large rotating masses, they tend to only spin at 1500rpm so don't contain anywhere near as much stored rotational energy as you might expect. Our steam flows end up so large that our turbine blades have to be so long that at 3000rpm the tips would break off.

We might need more intelligent load control - so that (for example) EV battery chargers, direct electric heating of buildings and so on can be load shed. That could be done by web-based control or even maybe automatically if the frequency goes below a preset level. The problem with the latter would be to avoid creating more instability. More local generation would help, too. If each town and village had enough to run essentials, a loss of grid supply wouldn't matter nearly as much.

DerekC said:

We might need more intelligent load control - so that (for example) EV battery chargers, direct electric heating of buildings and so on can be load shed. That could be done by web-based control or even maybe automatically if the frequency goes below a preset level.

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The problem is the response time is going to have to be milli-seconds, and possibly not even then.
By the time a frequency detector has seen the frequency is dropping like a cliff it will probably be too late, and a web based system will have latencies that add up to at least a substantial fraction of a second.

DerekC said:

The problem with the latter would be to avoid creating more instability. More local generation would help, too. If each town and village had enough to run essentials, a loss of grid supply wouldn't matter nearly as much.

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Define essentials?
You'd have to rewire every house and probably much of the distribution system to separate out an "essential" and "non-essential" supply. And we all know people would start rewiring their houses back on the sly.
Local generation is a red-herring, its considerably more expensive and less reliable.

The solution to this problem is simple - National Grid should not have been allowed to run the grid into the ground like this, they were in breach of their network standard so they rewrote the standard to save themselves some money.
What they should have done is arranged for sufficient spinning reserve/synchronous spinning mass to provide the system inertia to ride through the fault until Dinorwig or similar facilities could reach maximum power.
They chose not to do this because all they care about is making money.

EDIT:

Another option is to provide a clutch between peaking gas turbines/gas engines and their generators.
That way when they are not in use for peaking operations their generators can be operated as synchronous condensers.

Some industrial users accept load-shedding in return from a discount on their charges. Could the equipment that controls this cut the non-essential supply instantly if the frequency goes beyond a certain limit, thus avoiding latency of receiving a central command? The cut-off could be slightly randomised around an average to avoid everyone cutting out in the same instant, and include some hysterisis (so it wouldn't cut back in until the frequency had gone well above the danger zone) or a time delay to avoid oscillations as it cut out and back in.

Roast Veg said:

Perhaps we need a national flywheel to maintain a bit more stability.

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That is basically what we had when we had plenty of large 500MW and 660MW steam turbines on load. Now there is little or no high inertia rotating plant to keep the system frequency more stable when unexpected events occur.