Academics and the grid. Part II: Are they studying the right things?

From Climate Etc.

By Planning Engineer (Russell Schussler)

Influential academics as a body are encouraging an energy transition to renewables, discussing remote hopes and ignoring huge obstacles and greater costs, which will worsen reliability and eventually result in unbearable blackouts.

Part 1 of this series discussed how the findings of academics are often misunderstood so as to make the transition to a high level of renewable penetration seem much easier than it will be. A major part of the problem is that academics study some problems, determine those are solvable and that is then misinterpreted to imply that greater emerging problems are also solved or easily solvable. In this posting we will look at what Academics are studying to determine if they are asking the right questions.

An earlier post discussed many reasons why approaching net zero would be challenging.  For now we will focus on one major challenge to solar and wind penetration.  Before any large generating resource can be connected to the grid, detailed interconnection studies must be performed. These studies seek to determine what will be needed to make sure the resulting system is robust enough to meet requirements for dependable stable operation. If the system in the area is strong and the resource adds additional robustness, then the interconnection requirements are minimal. If the system is weak in that area and especially if the connecting resource “leans” on the system, then significant costly improvements  and additions may be needed in the area and across the wider system.

What makes a system strong or robust?  In additions to high-capacity transmission lines, the anchoring source is large rotating machines that operate in synchronism with the grid. They provide inertia, they can respond quickly through ramping, they can inject vars, they increase short circuit MVA (mega volt amperes).  All good things necessary for a reliable power system.  Asynchronous generation, sources which don’t spin with the system, such as wind and solar, do not as readily add strength to a system; rather they tend lean on other resources.

Synchronous generators provide essential reliability services  which are needed for the operation of the grid.  The primary services are voltage control, frequency control and balancing services. Conventional generators (coal, natural gas, nuclear, hydro) readily provide these ser vices because they rotate in synchronism with the grid.  Not all resources do.  To quote from the US Office of Energy Efficiency & Renewable Energy”:

However, newer technologies such as wind, solar, many energy storage technologies, and new types of load controls operate through the use of power electronics and control systems that don’t operate in the same way as historic technologies. Newer technologies offer interesting (bold italics added) opportunities because their control systems can be tuned to operate similar (bold italics addedto conventional generation.

Rest assured the “interesting opportunities” offered by newer technologies will be extremely challenging, and before these challenges can be met much research development and successful engineering will need to be performed or the system will dangerously degrade.   Also note the use of the word “similar”; do not believe that it means “similarly well in a satisfactory manner.”  (I can throw a football similar to the way Tom Brady does, but believe me I could not sustain a high school offensive drive.)   The challenges associated with integrating large amounts of wind and solar do not consist of minor details that can easily be worked out once we find a way to get enough megawatt hours at the right time from wind and solar resources to replace fossil fuel resources.  Wind and solar will add complexity, cost and uncertainty for a long time. The less well these resources perform, the greater the likelihood of service reductions and blackouts.  As noted, solar, wind and batteries, when providing power to the grid, typically lean on conventional technology.

It is a crucial question as to what will provide support when wind and solar have displaced the major supporting elements of the power grid. Hydro capacity is pretty well maxed out in most locations. Nuclear has potential to reduce CO2 while supporting the system, but faces considerable social and political challenges. Without some currently unspecified approach to add significant robustness to the system through the provision of essential reliability services, the increased retirement of conventional synchronously rotating generation and its replacement with asynchronous wind and solar will continue to make blackouts and outages more frequent and severe. There is much work to be done to make solar and wind better emulate essential reliability services, but such work is in the early stages and the results are at best mixed. Let’s look at what is being studied by academics supporting a net zero transition. One would hope that these major concerns would be a prime area of discussion and research within the academic community.

Conveniently as I was finishing up Part 1, I came across this article, Review on 100% Renewable Energy System Analyses—A Bibliometric Perspective. There has been a huge increase on scholarly publications relating to the net zero transition, as can be seen in the figures below taken from the article.

If we are serious about increased grid penetration from renewable resources, it is critical that additional successful impactful research be done. Breakthroughs will be needed in the planning and operating the grid to ensure reliability as the amount of asynchronous and intermittent wind and solar resources make up more and more of the generation mix. While batteries can help with the intermittency problem, they too are asynchronous resources, and thus may contribute to greater challenges.  Wind, solar and batteries push toward an insufficient supply of synchronous resources, which anchor the system through their ability to provide inertia, vars (volts amperes reactive) and other desirable system needs.

As noted in the article, the study of renewables to achieve a net zero grid, is an international effort with many links among the contributors. Of particular value is the graphic below supplied in the article which shows keywords from the published articles. This graphic describes what is is being studied and receiving attention.

There are a few key words linked to the major problems associated with grid reliability. The relevant key words are: intermittency, electric power transmission, transmission capacity, seasonal variation, power flows, backup capacity, microgrids, energy demand, weather and storage capacity. There are a large number of words associated with cost, which is good. However, the keyword ‘levelized costs’ shows up, which is a reminder many are unaware of grid issues. Levelized cost does not consider the grid impacts of generation resources and solely focuses on the economics of generation divorced from grid impacts.  This approach is very much out of place in confronting the challenges of obtaining a net zero grid. Trying to justify renewables by quoting levelized cost seems like either a major mistake or mis-direction.  There are many words tied to reasons for reducing CO2 such as atmospheric pollution, decarbonization, air pollutions mortality, global climate and, low carbon.  However, discussion of drivers and need are not helpful in figuring out how to achieve net zero. There are words linked to geographical locations where studies have gone on.  From my review it does not appear that any significant number of these studies are about the grid and how it might be made to operate, but rather mostly resource-based evaluations and justifications for the need to reduce CO2 and calls to action.

What’s striking and most concerning is what is not found in this graphic of key words.  Reliability, stability, inertia, voltage control, balancing, vars, spinning reserve, ramping, quick standby, contingencies, damping and oscillations for example. Words commonly associated with the interconnection process of new resources are nowhere to be found within this review of academic papers on the subject of a net zero transaction. Another notable omission is nuclear. Nuclear power is the best hope for a low carbon resource that could provide critical grid support.  Is the group collectively serious?

The article talks of Energy System Models (ESMs) used to evaluate energy systems. They describe one model thusly,” EnergyPLAN is one of the most widely used ESM tools to evaluate energy systems with high shares of RE (Renewable Energy), applying simulation assumptions.” Taking a lesson from Part 1 of this series that statement should be understood as saying,” EnergyPLAN is one of the most widely used ESM tools to evaluate certain very limited components of energy systems with high shares of renewable energy, applying simulation assumptions”. The other programs referenced can be described similarly as only covering a limited portion of concerns around the proposed energy transitions.  There is a lot of modelling and lot of studying going on, but evidently, the mainstream academics are not focused on the major challenges around generation, transmission and distribution of energy from asynchronous renewable resources nor are they concerned with promoting synchronous resources which could help.  These models are concerned with backup, transmission and capacity at only the most superficial and basic levels when it comes to power supply concerns.

Imagine a body of academic literature surrounding a proposed transition away from both animal and vegetable sources for human diets. Most would hopefully recognize the inherent insanity if the major keywords were flavor, texture, scent, appearance and satiety while words like health, calories, nutrition, protein, fats, carbohydrates and digestible were missing from the literature. A vast literature seeking to eliminate beams from skyscraper would be suspect if the keywords did not include words like loadings, shear, stress and vibrations. The situation with these studies as to the grids ability to handle net zero carbon appears equally insane and ridiculous. A group of studies this large advancing an agenda to greatly increase asynchronous renewable (wind, solar and battery) penetration should show some consideration of the major challenges that will need to be addressed.

Studies about how much energy can be produced from these resources, how it can be stored and how it can be transported, where transmission is treated like plumbing, do not help us advance past the significant hurdles which lie ahead. Seeing many nations advance in lock step toward the goal of increased asynchronous intermittent penetration with no well-studied remediation actions in place is frightening. Instead of joint cheerleading, we should be sharing and documenting the challenges to better work around them.

There are many technical publications and many technical journals which grapple with the concerns around essential reliability services.  For example, engineers, academics and scientists jointly grapple with the critical such as providing synthetic or virtual inertia through inverter technology to aid the Texas grid.   There is some hope that advanced computer controls can be developed so that asynchronous resources perform similarly enough to maintain the grid at higher penetration levels. It should be recognized that the talk is of possibilities not probabilities. Here the National Renewable Energy Laboratory concludes “Ongoing research points to the possibility of maintaining grid frequency even in systems with very low or no inertia”. The unsaid part of that statement is that it may not even be possible to maintain grid frequencies with low inertia. It’s also certainly in the mix at this point, based on the statement from National Renewable Laboratory, that in the next 20 years the best we may be able to do at higher penetration levels of asynchronous renewables is maintain frequency in a highly inferior manner with a boatload of reliability problems, with increasing blackouts at untenably high prices.

The published papers in this area tend to focus more on dealing with problems in the present as system needs are emerging, not critiquing or advocating for potential changes, nor warning of the dangers of the long-term trends. There are many general differences between the literature studying actual grid reliability concerns and the studies in the net zero bibliography. They vary as to advocacy, audience, visibility and impact on policy. Part III of this series to be titled “Visionaries and Problem Solvers” will discuss the differences between these two groups in more detail and compare their distinctive approaches and the important resulting implications.

While the academics I would term as “visionaries” do not highlight or study major grid reliability concerns, I think such concerns are becoming more well known to them. The typical approach of visionary academics, to concerns about observed and emerging grid problems, has been to call for “Smart Grids” as if that magically solves everything.  Modern grids are “smart” but as  with any “smart” technology there are all kinds of applications that could be adopted, so of course not all potential “smart” applications could be employed on any given systems. Some small subset of “smart” applications may provide particular benefits in some circumstances and make it easier for asynchronous wind, solar and batter resources to interconnect and operate with the grid. Unfortunately, it is common for renewable proponents to make the leap to presume that “Smart Grids” could solve many or all of the grid problems associated with wind, solar and batteries. This is a false and dangerous presumption.

This ties to one last observation from the IEE bibliography keywords: “Supergrid” comes up frequently in the keyword search. This is likely because the limitations of “Smart Grids” in accommodating intermittent power are becoming more and more apparent and undeniable. “Supergrids”, the next big thing, can be poised to stifle emerging worries and bolster hopes of greater greenhouse gas emission reductions despite the technical problems seen by conventional grids and even Smart Grids. Rest assured large “Supergrid” applications will introduce additional problems, complexity and many issues which will need to be solved. They do not deserve to be considered as the next magic panacea.    Perhaps there are limited opportunities where the simplest “Supergrid” applications might be considered in a long-term approach across a wide area, but overall, the concept is highly speculative and not ready for widespread promotion.  Including the term in calls for a net zero transition only serves to misinform and distract policy makers.  It’s disappointing to find it as a keyword on the net zero listing. Especially in light of the many crucial terms that did not show up. We should be careful to ignore the distractions of what might be possible one day and advocate for plans consistent with reasonable expectations.

The academic literature arguing for a net zero transition of the electric grid focuses on lesser problems and ignores the larger roadblocks.  As a whole the body of studies might be seen to falsely suggest that the transition is within reach.  The papers in this literature should include the disclaimer: “This paper only looks at a limited set of problems associated with a net zero transition.  Solving the problem(s) studied here still leaves many unsolved and potentially unsolvable problems on the table and furthermore it is likely that this solution may aggravate existing problems as well as creating new ones.” Barring major breakthroughs in the areas of critical technical challenges (which don’t seem to be receiving a lot of attention at the policy level) the grid cannot reliably support the envisioned increase penetration of wind and solar need to get anywhere close to a net zero goal.  Influential academics as a body encouraging an energy transition while focusing on lesser concerns, discussing remote hopes and ignoring huge obstacles will lead to increased likelihoods of greater costs, worsening reliability and eventually unbearable blackouts.

Thanks to Roger Caiazza for review and helpful comments

Bonus Section

This link will allow you to see a 25 second clip of the Eastern Interconnection, the largest grid, responding to a fault and generator outage . On February 26, 2008 a substation fire caused a chain reaction that caused several system elements to trip off line, culminating in the loss of two large nuclear generating units. When generation is lost the rotating machines in the system very quickly increase generation. Because the loss was two large generating units, the protection schemes in Florida called for load shedding as well. The impacts of this event were felt throughout the entire grid. What the graphic shows is the patterns of generation in the east increasing and decreasing their frequencies to ride out this disturbance. In no harmful impacts were experience outside of Florida. This is because the large generators with their inertia were able to change frequency and dampen the oscillation. An electric system where the large rotating machines were replaced with today’s wind and solar applications would show great stress.  In an over stressed system, the observed oscillations would continue and grow until many units were tripped off the grid and the resulting instability led to widespread blackout.

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Alan Watt, Climate Denialist Level 7
January 13, 2023 10:53 am

Russell:

Thank you; I have found your posts very informative.

Question:

I infer that with existing technology HVDC imports are also asynchronous sources. I see an increasing number of “net zero” plans that rely on imports to fill the gap when wind/solar are not producing. Does that have any net effect on grid stability or is it a wash?

It doesnot add up
Reply to  Alan Watt, Climate Denialist Level 7
January 13, 2023 2:57 pm

Observation of reportable frequency incidents (i.e. when frequency goes beyond 50+/-0.2Hz in the UK is that the majority of them are now caused by interconnector trips. Last year, many were to the high side when export links failed. You can check out incidents in the spreadsheets here:

https://www.nationalgrideso.com/industry-information/industry-data-and-reports/system-performance-reports

It has to be said that Dynamic Containment using grid batteries seems to be working well to limit most of the frequency excursions, at least while the incidents are no bigger than ~1GW. What happens if Eleclink (1GW) and IFA1 (2GW when it gets back to full capacity) go down simultaneously (they connect to the French grid close to the French terminus of the Chunnel at Coquelles, near Calais, but in separate sites, and are effectively fed by the 5.6GW nuclear complex at Gravelines, just up the cost near Dunkerque – at least when it is working) is I am sure a question that troubles grid engineers.

Interconnectors do have “grid forming” power electronics – but of course that only works when they don’t trip and are transmitting power.

Tom Halla
January 13, 2023 11:34 am

It would appear that a fair number of influential people do.not have sufficient grasp of how complex an AC grid is. Encouraging wind and solar while ignoring the effects on grid stability is irresponsible.

JamesB_684
Reply to  Tom Halla
January 13, 2023 1:22 pm

I would assert that the vast majority of influential people do not have any grasp of how complex an AC grid is.

I’m an electrical engineer that works on the small “low voltage” AC systems isolated to an industrial crane, with a diesel engine spinning a modest AC generator to supply the very limited loads involved with lifting loads and moving the crane. I do not have a sufficient grasp of how complex the much more complex AC grids are. I readily admit that I’m not qualified to opine on huge changes to the AC grid, beyond asserting that we need a heck of a lot more reliable generation capacity, even without converting transportation vehicles to EVs.

Last edited 25 days ago by JamesB_684
Yirgach
Reply to  Tom Halla
January 14, 2023 6:09 pm

I find that the same lack of complex systems awareness appears in other disciplines as well. In the medical field, microbiology stands out as one of the most unpredictable and complex.
And for good reason.

vuk
January 13, 2023 12:13 pm

Current state of the UK grid
https://www.gridwatch.templar.co.uk
Nuclear 13%, wind 32%
click on the French flag at the top left corner and you see a reverse proportion
Nuclear 42%, wind 14%
despite fact that number of the French reactors are off the grid for long term maintenance.

vuk
Reply to  vuk
January 13, 2023 12:40 pm

EDF has taken about half of France’s 56 nuclear reactors offline which normally could be generating over 70% of its electricity. 

It doesnot add up
Reply to  vuk
January 13, 2023 2:02 pm

They’re back to about 41GW out of 65GW now, but I think some of that is premature: some plant will return to maintenance in February, but was brought back for emergency cover in the December cold spell.

Rud Istvan
January 13, 2023 12:36 pm

There are several bottom lines here.
Renewables are per se more expensive, else they would not need subsidies.
Renewables are actually much more expensive because their intermittency requires underutilized conventional backup. There is no grid scalable ‘storage’ solution. As a direct comparison, correcting EIA LCOE gave CCGT at $68/MWh, onshore wind at $146/MWh excluding subsidies. Details in ‘True Cost of Wind’ over at Judith’s.
Renewables provide no grid inertia, so are destabilizing. And beyond some penetration, these instabilities are not recoverable by the remainder of the grid.

And anyone who thinks otherwise is an ignorant fool. There are many: BoJo, Biden, AOC, Jacobson at Stanford, Kerry…

vuk
Reply to  Rud Istvan
January 13, 2023 1:22 pm

BoJo is ‘a has been’ for the net-zero cause, currently in pocket for about £1 million of an aviation tycoon and cripto currency financier based in Taiwan, who is known for supporting leading British anti-net-zero MP.
https://news.sky.com/story/boris-johnson-declared-1m-donation-from-crypto-investor-in-sign-he-wont-be-stepping-back-from-politics-12784477

Last edited 25 days ago by vuk
vuk
Reply to  vuk
January 13, 2023 1:41 pm

A DeSmog analysis of official records showed the gifts included £515,000 from the above financier. More here:
https://www.climatechange.ie/conservative-party-given-651k-by-aviation-industry/

D. J. Hawkins
Reply to  vuk
January 13, 2023 2:15 pm

Vuk:

who is known for supporting leading British anti-net-zero MP.

Isn’t that a bit of a mixed message? Is BoJo a net-zero moron, or is he just taking money from anyone who’ll drop it in his lap?

vuk
Reply to  D. J. Hawkins
January 13, 2023 2:43 pm

For ones “green c..p” comment author, £1 million is more than big enough incentive to go back where he was and snatch the Steve Baker’s anti-net-zero crown. If his current other half doesn’t like it, she would be welcome to follow all previous other halves, plenty of fish in the seas of British isles and further.

It doesnot add up
Reply to  vuk
January 13, 2023 2:58 pm

I’ll wait to hear what it has done to the skin on his rice pudding.

Joe Crawford
January 13, 2023 12:48 pm

It’s not hard to understand the limited knowledge academics have of grid operations when the largest grid they’re familiar with is the power panel in their house. They may even have a standby electric generator with an automatic power switch attached, read the User Manuals and think they know how the system works. Extending that knowledge to the local power grid is simple :<)

observa
January 13, 2023 12:51 pm

A major part of the problem is that academics study some problems, determine those are solvable and that is then misinterpreted to imply that greater emerging problems are also solved or easily solvable.

Everybody needs to get rid of fossil fuels to protect the environment. Right you are there Euros-
https://www.msn.com/en-au/money/markets/indonesia-palm-oil-export-curbs-biodiesel-plans-to-hit-world-vegoil-supplies/ar-AA16ju0I

Rud Istvan
January 13, 2023 12:56 pm

To repeat a comment to Part1:
It is a good thing that global warming is a mostly imaginary problem, because renewables are a mostly non viable solution.

RickWill
Reply to  Rud Istvan
January 13, 2023 2:14 pm

Wasting huge resources on a non-viable solution is a serious concern. Fortunately for the rest of the world, China and India are not pushing the madness and Japan is renewing its fondness for nuclear.

China will not be able to burn coal at present rate for the rest of this century without access to global resources. Australia will be a soft target for those resources.

RickWill
January 13, 2023 1:46 pm

South Australia as a near independent network has confronted the challenge of high penetration of intermittent generators. It is currently averaging 70% wind and solar over any year.

The sub 6 second inertia requirement was met with synchronous condensers. They have been up and running for about a year and the need to idle gas plant to provide rotating inertia has been diminished.

The network is not entirely independent. It uses the Victorian grid as a 600MW battery of infinite capacity. That is about 30% of the average generation.

Rooftop solar is close to supplying 100% of the lunchtime demand. That has created serious issues for local distribution as it is a challenge to maintain local voltage when rooftops are singing.. High voltage reduces the solar output and rooftop owners complain.

South Australia can now operate without the Victorian interconnector without running all its gas plant but the cost of 6s plus stability services goes so high that much of the wind generators shut down. Rooftops are not directly exposed to those costs.

So synchronous condensers is something that should be well studied as an option to provide sub 6s stability.

Also auto tap changing distribution transformers is a new essential element or distributed batteries.

The emerging challenge in Australia is EV battery charging in the woke high density inner city locations.

Last edited 24 days ago by RickWill
Eng_Ian
Reply to  RickWill
January 13, 2023 2:44 pm

A 600MW, infinite capacity battery. Actually, the SA grid can take 742MW from Vic via the two interconnect cables, (see AEMO web for data).

SA has nearly 2,400MW of wind generator, solar farms and a vague idea of the quantity of domestic PV connected.

On a good day, especially on the weekends when industry is drawing a lower demand, the generators often make excess, allowing export to the remainder of the east Australian grid.

Unfortunately, it all comes crashing down without that infinite battery that SA are not paying for. They aren’t paying for the upkeep, except through power purchases. They aren’t paying for the CO2 it emits, (if that is a concern) and they aren’t caring about the excess power flooding the rest of the grid and making the prices, (sometimes), negative which harm those coal and gas generators which provide the infinite battery function.

As far as I can see, SA is woke and is a parasitic drain on the grid. It’s time that they owned the costs associated with that battery and started paying a premium for the times they drain from it or discharge to it. If not, then someone else is paying and it’s not cheap.

It doesnot add up
Reply to  Eng_Ian
January 13, 2023 3:00 pm

Perhaps the lessons will come when nearly as woke Victoria shutters more coal and the backup is no longer available to either state.

Eng_Ian
January 13, 2023 1:46 pm

The lack of inertia associated with asynchronous generators on the grid could be resolved with ONE requirement.

Make it a requirement for the asynchronous generators to install a DC motor, sharing a common shaft with an AC generator. The AC generator is operated like any other on line facility, in sync and at the correct voltage. The DC motor is controlled to drive the shaft and maintain the AC load of the grid and is powered by the intermittent/asynchronous supply.

This would be no different to any other generator. If the wind/solar energy wasn’t present, then the generator could be removed from the system, (similar to a hydroelectric facility). When the wind and solar are only partially present, the DC motor would be brought to the required synchronous speed and then the generator would be connected to the grid. As more DC power becomes available, the DC motor applies more torque and subsequent AC current to the grid. IF the DC power drops, the torque diminishes and the current supply follows. If it gets to the point that insufficient DC is available, (the AC generator starts acting like a motor), then it is best to remove the generator from the grid and await more DC power.

Imagine IF the DC generators installed sufficient batteries to HOLD 24 hours of intermittent energy ON SITE, they could charge this battery and using control of the DC motor torque, they could drive the AC generator to provide 24 AC power using the battery to take out daily peaks and troughs. If low energy inputs were forecast for the next day, then the DC motor torque could be wound down to a lower value earlier, spreading the peaks and troughs over a longer period.

This is no different to hydroelectric plant with a finite dam. The dam however typically holds an energy store rated at more than 24 hours.

See, a solution is available, but it will cost the intermittent generator some storage and a large motor/generator set.

Now why isn’t this a network requirement?

Tim Gorman
Reply to  Eng_Ian
January 13, 2023 3:05 pm

ROFL!! You’ve just described a traditional power plant, coal, oil, or natural gas!

That coal, oil, and natural gas is your “battery”. The “battery” can always go flat if charging current is not available and the AC generator can’t recharge the battery while also supplying power. The coal, oil, and nat gas reserves can be sized to last a lot longer than a “battery”.

We just went through a period of extreme cold with overcasts lasting a week and intermittent wind during the period. Battery

Eng_Ian
Reply to  Tim Gorman
January 13, 2023 7:23 pm

I think you missed my point. I or I missed yours.

The battery is charged FIRST, ALL power from the renewable fleet goes to the battery.. The connection to the DC motor is FROM THE battery via a pulse width modulated controller, (or similar), so that the power drain FROM the battery is always trimmed to suit a forecast or to provide peaking power as required by demand.

The plan is to use the battery like you would a coal bunker, or gas bottle/fuel tank.

If there is a forecast for a week with no wind/solar/etc then clearly this system is going to go flat. I would not expect it to be much different to the present.

However, I am advocating that by using the AC generator as the OUTPUT from the renewable plant, there is the following benefits: –

  1. Spinning inertia is provided.
  2. Reactive power can be provided.
  3. Power output can be varied UPWARD to meet a local peak demand, exceeding the current in feed power.

I set the bar VERY low at a 24 hour battery, I don’t believe anyone, (think renewables), could or would provide sensible battery backup as required to supply the grid full time. The 24 hour was to provide a sensible amount of capacity to ramp up to daily peaks AND to allow for short periods of no in fed power, eg overnight for solar.

Like most people on here, we can see the problems with renewable power and this option is just one path to make them better for the grid. It is NOT the final solution.

Tim Gorman
Reply to  Eng_Ian
January 14, 2023 4:45 am

If there is a forecast for a week with no wind/solar/etc then clearly this system is going to go flat. I would not expect it to be much different to the present.”

This is the whole point of my post! Coal, oil, and nat gas powered generators don’t go flat, even after a week! (assuming sufficient storage capacity for fuel)

You seem to be describing a kind of a synchronous condenser with a load attached.

I think you are going to find that the battery requirement to fuel that “generator” is going to be huge, because of efficiency losses it would be less efficient than just directly converting the DC from the battery to AC.

If you are just using the “thing” to handle peaks and renewables being off-line for short periods, direct DC to AC would probably be more efficient. If you are expecting *complete* grid failure where spinning inertia is needed then the load on that battery is going to be huge, even just for a 24 hour period.

Erik Magnuson
Reply to  Eng_Ian
January 13, 2023 8:08 pm

What may be a better idea is to put firm restrictions on how fast a renewable can ramp power up and down with substantial penalties for exceeding those limits. One exception would be frequency excursions, where power could be ramped up quickly during a frequency dip and ramped down quickly when the frequency rises.

IMHO, every major (>5MW) renewable generating facility should have at least an hour’s worth of storage to smooth out dips and bursts of generation from wind or solar.

It doesnot add up
January 13, 2023 2:00 pm

I do not think there is much work on these issues in academia. On the other hand, there are definitely many projects at system operators attempting to tackle the real world issues. National Grid in the UK has conducted a number of groundbreaking developments, such as the direct measurement of system inertia, distributed blackstart experiments using unconventional sources, rapid frequency response, etc. A taster of what they are working on:

https://www.nationalgrideso.com/future-energy/projects

Now there is no guarantee that they are adequately covering the bases (especially since they failed to advise government how close to the wind it is sailing through loss of dispatchable capacity), and it is also clear that they are hammers looking for nails to hit: solve the problems by enlarging the business of the grid with more transmission, statcoms, synchronous condensers, interconnectors, etc. and advising government to pursue solutions that do precisely that – hence wind is preferred to boring nuclear which would not entail grid expansion or the need for the other fancy kit, and locational marginal pricing, which places maximum emphasis on the value of additional grid assets is preferred to other ways of organising the market and making more rational investment decisions. It becomes a self-reinforcing push to net zero, whatever the cost.

That is the real issue: cost is entirely subsumed to the latest Heath Robinson and Rube Goldberg solutions that keep the net zero plates spinning for now.

It doesnot add up
Reply to  It doesnot add up
January 14, 2023 3:46 am

More on what National Grid is up to here.

https://www.nationalgrideso.com/news/operability-strategy-report-2023

Reducing inertia to 102 GVAs, or about 2.5 seconds of demand seems to be quite high risk to me. It doesn’t allow much reaction time.

sherro01
January 13, 2023 5:40 pm

It is stated clearly in AEMO reports that their research follows government policy such as Paris agreement and net zero C by 2050.
This is why we have major problems. In a rational world, a body like AEMO would have a clean slate charter, not a restricted one.
In that rational world, AEMO would have a responsibility to advise governments and people of problems they observe in providing the cheapest and most reliable electricity.
Renewables are not the cheapest nor most reliable option. But AEMO maintains that their charter does not allow them to report this. They say they can report only pathways to low carbon like net zero and study of fossil fuelled is not allowed for them.
I have no idea who told AEMO to be quiet about these options. Surely people should be able to consult a formal body that covers all of the options, a body charged with responsibility to advise us that we are now on a dangerous path. Presently,. there is no body in Australia required to warn of dangers in the plans for the future.
Who benefits from preventing AEMO from study of dangerous choice? Why? How?

Geoff S

usurbrain
January 14, 2023 5:06 pm

VAR’s are needed to move electricity from one place to another. Most high school students learn that voltage flows from a high voltage to low voltage place. That works with batteries but would mean that you have 150 VAC closest to the Generator and 100 volts furthest from the generator. Each of these two values would destroy any appliance with a motor in short order. To move the voltage the utility dispatcher uses Volt Amps Reactive VARS. and achieves the transfer of current by causing a leading or lagging value of VAR.
Now thousands of Wind Turbines and Solar panels generate DC voltages, inverting them from DC to AC and use the frequency on the local power line to establish the frequency of the inverted power. This could easily cause a frequency chase which causes massive amounts of excess current circulating on the power lines between these generators. Then all it takes is for one Wind Turbine to drop offline and it snowballs into an outage.
Who reading this wants to design a system that monitors the voltage, frequency and VAR’s of every Wind turbine and Solar panel attached to the grid and a computer to control each of these devices and achieve what a rotating thousand+ pound Coal or Nuclear Steam Turbine and AC Generator does naturally? This would be like using a computer and AI to replace all air traffic Controllers.

Erik Magnuson
Reply to  usurbrain
January 15, 2023 4:50 pm

Comment about VAR’s:

The original LADWP line from Hoover Dam had a higher voltage on the LA end than on the Hoover Dam end. This was done to improve stability and the higher voltage was provided by producing more VAR’s on the LA end than the Hoover dam end.

A common question would be: Why the power flows from a lower voltage to a higher voltage?

The answer is that in AC power systems is that the power flows from where the phase leads.

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