Interesting read Greg, thanks for sharing. Some parallels with the UK as our older thermal plant retires while the number of wind turbines and interconnectors to Europe both increase.

Pie in the sky stuff by the State, and the residents will suffer. Plenty of coal in Australia, but South Australia now has no coal fired plant. The quote in the attached article says it all "We have not yet got on top of how to manage intermittency". Wind, solar, geothermal...they have it all, but it is all intermittent.

http://www.afr.com/news/south-australia-energy-use...

Table 4 is pretty interesting. It looks as though the ride-through setting of each group of turbines was set in different ways, and the ones that were set to be most persistent and fault tolerant hung on to the bitter end. No surprise really. The other ones conked out in a cascade of failures, overloaded the interconnect, and blew the big fuse. The State Premier is trying to blame it on the transmission line failures, not his precious wind turbines.

Cheers

Greg Locock


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I'm curious, what is the population of the affected area?? How many deaths, say due to electrical failures at hospitals have been attributed to this incident?. I'm guessing that weather in this part of the world is pretty mild in September and nobody froze to death. Here in Canada, Alberta with a population of 4 million is heading down this road, shutting down coal fired station, subsidising wind and solar, ( today's temperature minus 20 Centigrade). Ontario, population 14 million is further ahead, shutting down coal plants, refusing to build gas powered plants, nuclear plants coming towards the end of their life, already has some of the highest hydro rates in North America.

Even with a population of 14 million, I suspect that any similiar incident here will not produce the necessary outrage to cause the politicians to start to understand science and engineering. It will take a massive death toll somewhere in the USA with a high population density and a black out in severe sub zero temperatures for common sense to set in. Cities in Germany, Sweden etc might get a bit cool occassionaly but I don't believe anywhere in Europe is taking the same levels of risk.

In our part of Alberta we had a build-up of freezing condensation on our distribution lines that caused multiple outages over a wide area in November.
Our power was out for about 21 hours. I fired up the standby diesel and we had no issues with heating or water or sewage (both on pumps).
We did lose our cell phones and internet connections as soon as the standby batteries went dead.
I should install an indicator light to tell me when the grid is back, but for now, my neighbour does not have a generator but he does have a pole mounted yard light. He leaves it on 24/7 and it is easy to see from our place.

Bill
--------------------
"Why not the best?"
Jimmy Carter

miningman - Few if any deaths have been identified. Certainly many problems with backup generators were demonstrated. You are right, in warm climates power failures are fairly benign, cold is far swifter. Total population affected is less than 2 million.

Cheers

Greg Locock


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Interesting that wind turbine protection only offers a restricted number of low voltage ride through incidents before tripping. Does anyone know why - is it because they are usually DFIG (double fed induction generators.

In the UK we are consulting on DfG (Directive for Generators) and I wonder if National Grid realize this.

I know of one utility in Canada using JungleMUX equipment and fibre optic cables running with their transmission lines to isolate faults and avoid "Domino" type progressive trips and the resulting large grid failures.
Is this a one time installation or is JungleMUX becoming widely used for utility protection?
Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

Well, I'm sure the bright lads in Canadia have thought of this, but if they sent a master clock signal over the fibre optics then all the windfarms and PV and hydro installations could sync to that after a blackout and the whole system should be able to re-synch gracefully.

Incidentally a friend of mine stuck his DVM into the wall socket the other day and measured 277V RMS (on a 240V service). Sunny day, affluent neighborhod, lots of PV systems feeding into a cranky old distribution network.

Cheers

Greg Locock


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Looking at the graphs it looks like the system collapsed in about a second.
As I understand it, somewhat simplified, A number of wind turbine sources were seeing the same disturbances. Apparently they were all set to allow the same number of ride-throughs before tripping and so all tripped at the same time. With that much capacity lost, one of the main interconnects for imported power, the Heywood interconnector, overloaded and tripped off. From there it was all over in a few cycles.
Have I made any major errors here?
I suspect that the system will go to a system of staged WT shutdowns to allow time for the load shedding system to respond.

Bill
--------------------
"Why not the best?"
Jimmy Carter

They have just had a fourth wide scale blackout. The State Premier is busy pointing fingers all over the place. It doesn't really matter, the whole state is a retirement village, with a few government funded employment facilities for those not old enough to live on a pension.

Cheers

Greg Locock


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Great post Greg... I suspect other parts of the world will see a similar type of failure... Canada, included.

Dik

Back in the early 2000's California experienced a summer of black/brown-outs but it turned-out that they were the result of the manipulation of the energy markets in the Western United States by the now infamous Enron Corp. They would create a situation where it appeared that the supply of energy was less than the demand thus forcing the utilities to purchase power from out-of-state sources at elevated prices thus padding their profits. This and other events eventually led to the failure of Enron and the resulting scandals that followed.

Now I'm not suggesting that something like this is happening 'down under', but you never know...

For those interested in what happened in California:

https://en.wikipedia.org/wiki/California_electrici...

John R. Baker, P.E. (ret)
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Irvine, CA
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It does get hot here in the summer. South Australia wasn't even using all of its gas fired capacity this time. Go figure.

http://www.abc.net.au/news/2017-02-09/sa-heatwave-...

Hoxton,

The crowbar or IGBTs are probably set to short the rotor DC bus before the power electronics overheat due to high currents on DFIGs. After several disturbances, they probably can't follow the LVRT curve due to already being hot.

Thanks - makes sense

Just a question to ponder: But if we use electric cars and the power is off, is that a good reason to not go to work?

carrying that ponderance farther. If you work for the Utility,would they require you to have a NON electric vehicle, so you can get to work during an outage

Funny that I see all the NON-electric trucks plugged in every morning.

We use several natural gas trucks, but mainly for servicing natural gas customers.

Cranky,

Of course you shouldn't go to work in that case. Haven't you read the plans about the grid using everyone who has a car plugged in to shave peaker generation? :)

I would hate it if the utility cycled my batteries but it does make me wonder how many cars you would need to black start a region. In places like India, where a lot of people have backup generation since the their grid is unreliable, I could see people using their car deal with power quality issues. After Hurricane Ike, here in Houston there was a guy using his electric car to power his house instead of a generator like everyone else.

Not much point in going to work if the grid is down. What are you going to do when you get there- fire up the grate and start blacksmithing?

Cheers

Greg Locock


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My employer has standby power at every important location. A significant grid outage guarantees that I will be called in to work, assuming that there is a building, trailer or habitable piece of earth to report to.

Quote (cranky108)

But if we use electric cars and the power is off, is that a good reason to not go to work?

Actually one of the reasons that I have no interest in an electric car. If there's ever a prolonged major outage (can you say "The Big One"?) I'll absolutely be expected to be showing up for work, may even be camping out at work, and can be refueled from our stock of gasoline; an electric vehicle seems a "system normal" luxury, not a system restoration necessity. Probably means that we won't have to worry too much about interference from the VP that drives the Tesla.

David, I would also have to be at work. This was a random thought that I had about electric cars (golf carts).

I had about the same thoughts as I watched the news last night, and a story about protesters demanding 100% renewable electric service.
I thought what dreamers.

South Australia is becoming a great argument for the proposed '50% renewable energy by 2030' target

Trenno,
I take it you mean "argument against". Or is that sarcasm?

Definitely sarcasm.

I think we have a responsibility to adopt best practice in terms of environmentally sustainable power generation, but some of these figures being spouted are just ludicrous.

Here's a chart of the predicted situation in SA for the next couple of years

So they need 550 MW of generating capacity

Cheers

Greg Locock


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The US has lots of coal available.

Australia doesn't need to import coal, cranky. It exports 90% of its own production. It just needs to build more generating capacity. The problem is planning and governmental courage. The governments here are run by a conglomeration of people from all walks of life, not many of them technically literate.

I won't start a separate thread for this, but it is another example of the same government inertia problem. In Brisbane where I live, a new commuter rail line was recently built and opened. But this new line has now thrown the entire commuter system into chaos, because a fundamental planning issue was overlooked...they forgot to train enough new train drivers. Apparently, it will be another year before the "trains are fixed".

We get the government problem every year with a new city panel.

Yes Australia has coal, but it seems like not much will to use it.

Clean coal fired power plants are the way forward, at least until renewable energy becomes socially and financially viable/sustainable.

As the author of the below article tells us: NOT SO FAST:

http://www.popularmechanics.com/science/energy/a49...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
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In some locations most of the anti-CCS arguments in that article don't stand up to reasoned analysis. For example in the UK there's an established network of subsea and on-land pipelines which were part of the North Sea gas system. The North Sea oil has many depleted gas reservoirs which once held methane for millions of years, and have wells and pipeline infrastructure available to inject CO2. Geologically the North Sea is well-understood because of the intensive oil & gas survey work over the last 40 years. Not all locations have such promise for CCS, but some certainly do.

The newest supercritical power stations are far more efficient than those of fifty years ago which helps to offset the large internal energy use of a CCS-equipped plant. The overall efficiency of supercritical-with-CCS power plants takes efficiency back to roughly where the industry was in the late 1960's, but without the pollution. Not ideal, but not disastrous considering how many coal-fired stations date from the 1960's in the UK and probably elsewhere too.


What method(s) of reliable baseload power generation do you favour John?

It would require a diversified scheme, based on natural gas, hydro, geothermal for the baseload and then add in solar and wind. Also, with the advent of battery storage becoming more technically feasible, that could help sustain the contribution to the grid from cyclical sources like solar and wind. BTW, I'm not saying that 50 years from now, perhaps sequestration technology may have advanced to where 'cleaner' coal could sill be an option in certain places and situations. However, we still need to work on more efficiency in both distribution as well as consumption. More widespread use of LED lighting for example, for not only residential/commercial usage but also infrastructure like public lighting of streets and highways could have a significant impact. And who knows, someone may yet crack the secrets of a sustainable 'fusion' reaction

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

I am struck by some inconsistencies in the Popular Mechanics article.

Quote (PM)

about one-sixth the cost of oil or natural gas per Btu

Quote (PM)

While estimates vary, a coal-fired power plant would have to burn roughly 25 percent more coal to handle carbon sequestration while producing the same amount of electricity. That would mean a vast expansion in mining, transportation costs and byproducts such as fly ash.

An increase of 25% in the use of a fuel that is 1/6 the cost of many alternative fuels is characterized as a "VAST" expansion.
Possibly an overstatement.
Bill
--------------------
"Why not the best?"
Jimmy Carter

I would add caution to injecting CO2 into the ground, as we should have seen the news about earthquakes in Oklahoma from salt water injection in such formations.
Not that anything as such would happen, but be sure before we proceed.

Solar sort of make since to a point, as the sun shines at the times most humans are active. But we would need to watch the duck curve, and be sure we have the generating capacity to handle sundown.

I am amazed that pre-treating of coal has not taken off more. And that no one has built an actual coal gasification, and gas turbine plant (at least that I know of).

coal gasification is pretty ugly, if you mean the old UK town gas plant. Lots of sulphur and stinky tar.

Cheers

Greg Locock


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And don't even think about underground coal gasification (as distinct from fracking). Wherever UCG has been tried, it has failed and created a contamination nightmare.

A couple of thoughts re: heavy oil, and by extension, coal.
There is a process to upgrade heavy oil into a lighter product by the addition of hydrogen. Can this process be used to upgrade heavy oil or carbon (coal) all the way to propane?
It looks good in theory but what are the practical issues?

Bill
--------------------
"Why not the best?"
Jimmy Carter

I might be wrong but isn't Waross' suggestion known as SASOL as developed by the South Africans around 1950??

Sasol is CH4 to heavy hydrocarbons, ie gas to liquid. Coal to liquid hydrocarbons (CTL) is Syngas plus Fischer Tropsch process, developed by the Germans 90 years ago. Syngas is very similar (or identical) to the way town gas was made in the UK, lots of stinky sulphides and smelly tar as a byproduct.

In an ideal post oil/NG world (we are talking the far distant future here) we'd use CTL or a variant to make hydrocarbons to fuel the awkward applications, principally aircraft, and nukes+greeny preferred renewables for electricity (and hence road transport).

Cheers

Greg Locock


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Modern coal plants also emit sulfur, but that is cleaned up in the scrubber. So why is town gas thought of as more stinky? Can town gas not be scrubbed?

I think the process of breaking heavy oil to smaller hydrocarbons is called cracking. But what would be your hydrogen source? Maybe natural gas or steam?

Much of the sulfur reduction in the US has come from burning low sulfur coal from the west, and less from eastern and middle US coals.
It tends to cost less than additional scrubber equipment.

I have no idea what type of coal exists in Australia.

With all the talk of the cheap plentiful coal in the US, is this of the variety that is obtained via mountaintop and stream valley destruction mining?

And at what point do we start seriously considering conservation/efficiency as a means to addressing these problems. Given all of the negative externalities associated with energy production and consumption, shouldn't this be the first order of business?

Are you suggesting reducing consumption of goods as a way to decrease energy usage? Yes we know that works.

Just what method do you propose using to reduce consumption of goods?

Unfortunately the political rhetoric of late has concentrated on the idea of reviving the coal mining industry in the United States with most of the attention having been focused on those places where miners have lost their jobs, which are in the coal fields in the Eastern part of the country, mostly places like West Virginia and Kentucky. Note that these are where obtaining the coal often does result in the destruction of mountaintops and valley streams and rivers. And as noted, this is also coal with higher sulfur content. Even those industrial and financial experts who are supporters of fossil fuels agree that the move from the use of Eastern, higher-sulfur coal to Western lower-sulfur coal was inevitable from a financial point of view, with additional motivation due to the negative environmental impacts and consequences of mining in places like West Virginia and Kentucky. To suggest that there will be any meaningful revival of coal mining jobs in these Eastern coal fields is simply naive at best and downright political expediency at worst.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

It is the exports through Norfolk that have been curtailed by the Obama assault on the coal industry.

http://www.eia.gov/todayinenergy/detail.php?id=252...

as if that were the only issue:
"Lower mining costs, cheaper transportation costs, and favorable exchange rates (compared to the U.S. dollar) continue to provide an advantage to producers in other major coal-exporting countries such as Australia, Indonesia, Colombia, Russia, and South Africa."

TTFN (ta ta for now)
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Maybe the coal miners should become gas drillers to drill and frack the coal seams. But that might produce too much gas.

Which leads to another question, is there anything else in the ground that can be mined?

Gold, silver, copper.

Usually, states that have coal don't have other things. WV, in particular, being known for coal, does not have much in the way of precious metals. Conversely, Virginia has little or no coal, but did have gold, and was a major producer of gold until California's gold rush. Of course, trying to make a living mining gold in Fairfax county, VA, is probably a losing proposition nowadays, particularly given that it's mostly placer mining.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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Looks like we're going to be able to experience the same issues as South Australia soon. They're now militating to kill Washington State's only nuke because........"we can replace it with solar which will cost less". Sheesh.

Keith Cress
kcress - http://www.flaminsystems.com

Well they are right. It does cost less. When it works. Yesterday, in the Australian summer, my off grid solar was working at 20%nominal, at one hour before solar noon.

Cheers

Greg Locock


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What ever happened to the repeal of the laws of physics?

Honestly we will need to see blackouts before anyone wakes up here.

Maybe they can use tidal power in Washington. That's been thrown around but never proven.

You'll probably have the opportunity to watch it here instead of doing it yourself - within a couple of years I think we'll see demand exceeding capacity in the UK as the older plant is retired because of environmental / pollution problems and the LCPD.

The final report on this is available here. Interesting reading.


http://www.aemo.com.au/Media-Centre/AEMO-publishes...

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

Do they (UK or SA) let their prices fluctuate or are they fixed?

SA price are fixed from time to time by the power companies and the government.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

As I understand it, power generators in Australia bid to supply power in 5 minute blocks, and get paid averaged over 30 minutes.

And if you want to watch the prices and the energy fluxes in real time, https://www.aemo.com.au/Electricity/National-Elect... is a great place to start.

There's also the historical data for download.

The final report says that the wind farms reduced supply rapidly as a result of transmission line failures, overloading the Heywood connector, which cut out, resulting in the collapse of the entire system. The Dear Leader of South Australia is adamant that his windmills aren't to blame. Strangely the traditional generators stayed on line right through to the blackout. I think the Dear Leader is going to pass a bill banning high winds so that he can meet his renewable energy target.

Cheers

Greg Locock


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SA may be more worried now that the Hazelwood Coal Power Station has closed.

it mentions that the inverter storage software can be configured to provide inertia? is that blowing smoke or possible. 800 tons at 1800 rpms is inertia!

I proposed exactly that a while back. I imagine some way of broadcasting a nominal clock pulse across the state , and the inverters were configured to be driven by that, rather than the local transmission line clock speed. If only there was a way of transmitting clock pulses over long distances. Once we've solved that, say by about 1900, the rest is easy.

Sure, it would cost about $43 in hardware.

Cheers

Greg Locock


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Quote (byrdj)

it mentions that the inverter storage software can be configured to provide inertia? is that blowing smoke or possible. 800 tons at 1800 rpms is inertia!

Google "synthetic inertia" and wind turbines. The trick in the inverter is for it to be able to take the inertia stored in the wind turbine and pass it through to the electric grid.

Quote (GregLocock)

I imagine some way of broadcasting a nominal clock pulse across the state , and the inverters were configured to be driven by that, rather than the local transmission line clock speed.

GPS clocks have been around for some time, which allowed synchronised time to be available almost anywhere. But I'm not sure what the intended benefit is in using a synchronised clock pulse to drive the inverters.

The advantage would be that it would increase their ride through tolerance, or if you like, it would add more inertia to the system.

Cheers

Greg Locock


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I'm not sure that would actually matter or help. In a system with actual inertia, the frequency would be continually varying as everything found a new stable operating point (or not). Without extremely robust communications I'm not sure that any combination of artificial inertia devices could adequately perform that dance. That isn't to say that it couldn't be less bad than it is, nor that artificial inertia couldn't help up to some point, but I'm not convinced that a wide area system can simply rely on artificial inertia.

It might be possible to design an electrical grid that didn't need inertia, whether real or artificial, but we're far from implementing such a beast.

I've worked with largeish machines that simulate inertia quite happily, it's mechanics 101.

Cheers

Greg Locock


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Here's another problem with simulated inertia, if you can't model it, and communicate that model to the planning engineers, then it can only be assumed to not exist. Inverter manufacturers have done a poor job of communicating with the system planning engineers, let alone the protection engineers. So to date, most of the utility engineers can do nothing but discount the statements of the inverter manufacturers.

The issue might be that there is a third party involved, called the customer, who has no idea that any of this information is important.

So none of us will really know how the system will respond, until there is an event. And even then, any units not within the event won't be known.

And why wouldn't you model it?

Cheers

Greg Locock


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Model what? Hot air? 'if you can't model it, and communicate that model to the planning engineers, then it can only be assumed to not exist.'

Inverter manufacturers have done a poor job of communicating with the system planning engineers, let alone the protection engineers.

I'll try again. I have worked with large electric machines that specifically simulate inertia (chassis dynos). Therefore it does not seem intrinsically impossible to alter the output of an electric drive system to simulate inertia. To point out the obvious my off grid inverter simulates a high inertia, that is, its output frequency does not change as the load changes.

Cheers

Greg Locock


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Is it that the inverters are allow to operate at max output and thus have nothing to add when needed.
I recall steam turbine plants that were not allow to operate at CVWO because of contract to be able to support grid stability.

No, the issue is that the output of the inverters is locked (in ways I do not know) to the clock frequency of the transmission line, and, obviously, its voltage is greater. So for example my on-grid inverter tracks the clock frequency of the local line, but does not attempt to drive it. It pumps electricity in by delivering a higher voltage than the transmission line. That is if the TL is operating instantaneously at V.sin(w.t) my inverter delivers (V+dV).sin(w.t). A truly synchronous machine would actually drive the transmission line at (V+dV).sin((w+dw).t) where dw is the difference between line frequency w and the synchronous generators speed.

Any reasonably gifted electrical engineering student can design a motor controller to accomplish that efficiently.

Cheers

Greg Locock


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So, you want to phase lock all the inverters throughout the system to a remote master clock, so if they happen to be disconnected from the grid at some instant in time, and you want to reconnect them to the grid, all you have to do is close the tie breaker, without having to check or adjust the phasing first? Sounds possible technically, perhaps less so politically.

OR, could you implement a persistent local phase lock, that would just keep the local inverters' clocks running pretty much in sync with the grid even through a disconnect of some specified finite time? Sounds like something that could be sold as a product improvement, or maybe mandated for new designs, and rolled out with normal replacements as the supply chain flushes.

Mike Halloran
Pembroke Pines, FL, USA

A truly synchronous machine does not operate above the grid frequency, otherwise it would be an asynchronous machine. It is much the same way that the turbine operates at the same speed as the generator--it is not turning at a slightly higher speed, although it would speed up if the shaft broke in much the same way that a generator would if its connection to the grid were lost.

With regards to inverters, they do not need to be all synchronised to the same independent clock source to be able to provide synthetic inertia. All they need to do is be capable of providing a brief overload in the event of system frequency dropping. Plenty of wind turbines already have this capability.

Yes they could do it, but thdy didn't.

Cheers

Greg Locock


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And if they did, there simulated anything could not be used as an input to power system studies, because the inverter manufacturers don't want to provide information to the public.

Utilities would need to install spinning devices because they can not count on inverters with unknown synthetic inertia.

And what master clock are you talking about? There is no master clock, other than the speed of the grid, which ever one you are on. None of them operate at any exact speed, but at a ball park speed.

With synthetic inertia, I guess it pulls power from the system to motor the turbine if the system is accelerating?

" None of them operate at any exact speed, but at a ball park speed."

I don't know about now, but, at least in the US, they used to be at an exact average speed, as many AC-powered clocks used the line frequency as a clock reference. This allowed AC clocks to be accurate to better than a second per year, or so.

I'm not really following parts of the discussion here, since "inverters," by definition, are converting DC to AC, and as such, they have to be phase-locked to the line frequency to efficiently transfer power. They are nominally crystal-driven to the 60-Hz line frequency if they are free-running, but if they're connected to the grid, they phase lock to the grid's frequency. Which means. they'll accommodate variations in frequency, up to a point, assuming the changes aren't rapid and random.

TTFN (ta ta for now)
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I think this discussion of synthetic inertia is misleading. There is no such thing. What the inertia of a generator provides is energy storage, period (full stop). In an inverter generator this would be provided by batteries, capacitors, or even a flywheel/generator. Diesel or steam generators are just more robust than inverter generators where the weakest link is the solid state electronic components

"With synthetic inertia, I guess it pulls power from the system to motor the turbine if the system is accelerating?" Yup, regen as it is known in the electric car game.

Cheers

Greg Locock


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With the recent decision by one of the US grids to no longer keep the grid speed to keep clocks accurate, the exact average speed is no longer true. If you want an accurate clock you need to purchase an atomic clock.
So what we will have in the US is a ball park speed.

I can't speak as to what the other two grids are doing for speed stability.

Machine inertia can provide close to fault current levels of energy into the grid, where inverters are self limited to some level the semiconductors can handle. The issue is the machines are braced for the higher levels of energy for a short duration. But inverter inertia could potentially provide energy for a longer time into a larger system event, but only if there is a source behind it.

Quote (GregLocock)

No, the issue is that the output of the inverters is locked (in ways I do not know) to the clock frequency of the transmission line, and, obviously, its voltage is greater. So for example my on-grid inverter tracks the clock frequency of the local line, but does not attempt to drive it. It pumps electricity in by delivering a higher voltage than the transmission line.

This only works for a DC transmission line. And with a DC line, clock frequency is meaningless.
Inverters imply AC.
Raising the voltage will cause a reactive current to circulate but will not transfer power.
To transfer power, the inverter frequency must be a fraction of a cycle ahead of the grid frequency. That is why a grid reference is needed.
Consider a diesel generator. When the generator is synchronised, the output wave will be in step or almost in step with the grid and little or no power is transferred to the grid. As the throttle is opened the sine wave of the generator pulls a little ahead of the grid sine wave. Still the same frequency but a few degrees out of sync.

Bill
--------------------
"Why not the best?"
Jimmy Carter

I see what you are saying but on sunny days my neighboring suburb sees 270V on a 240v service because every man and his dog has on-grid pvs.

Cheers

Greg Locock


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On the inertia via electronics thing, I've just read that in the USA generators that can provide grid frequency stabilization are paid extra (good), and that 38% of that capacity is from batteries. So despite what some people above have claimed there is no problem with using electronically commutated supplies for grid stabilisation, at least up to 38%.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

That 38% from batteries makes no sense at all. There's no large scale battery storage systems on that scale. We're pondering systems that might get to 2 or 3% but nothing firm. I'm not aware of other utilities doing so either.

If one were to look at the ringing on a power system event recovery, the batteries would help in the longer term stability. But I have my doubts in the shorter term stability. I think you need some ratating mass for that. And maybe that's the point of having both, to shorten the ringing time.

I also agree that 38% battery sounds high.
38% of 1.5 TW= 570 MW (Hr) battery?

I don't know about being paid extra, but each company is required to have some amount of spinning reserve, and hot standby. Wind and solar can't do that. But energy storage can if it is big enough.

The key is more likely the ramp rates of each unit, or combined ramp rates of several units.

cranky,

Over here the CCGT generators are paid for 'ancillary services' other than simple generation. Gas turbines can respond more rapidly to changing system conditions than steam turbine stations which need time to increase boiler firing rate, and one of the ancillary services provided by the GT's is frequency correction, whereby the turbine governor becomes more aggressive in response and the firing limit of the engine is raised above the normal operating limit, thus allowing the engine to be over-fired in a bid to prop up a falling grid. It eats up hot parts life at a disturbing rate and understandably the machine owners want to be financially compensated for the loss of engine life before the machine has to be rebuilt.

No 38% of the frequency stabilisation is provided by batteries. Not 38% of capacity. Ah, found it, I was wrong, it says 38% of PJM(the largest comptitive electricity market in the world)'s frequency regulation is from non traditional capacity (flywheels batteries etc). Not the USA as a whole.

Here's a company that is doing what i proposed

https://www.forbes.com/sites/peterdetwiler/2014/01...

and here's why

http://www.utilitydive.com/news/ferc-seeks-input-f...



Cheers

Greg Locock


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from the BBC,

"An Australian state will install the world's largest lithium ion battery in a "historic" deal with electric car firm Tesla and energy company Neoen.

The battery will protect South Australia from the kind of energy crisis which famously blacked out the state, Premier Jay Weatherill said.

Tesla boss Elon Musk confirmed a much-publicised promise to build it within 100 days, or do it for free.

The 100-megawatt (129 megawatt hour) battery should be ready this year.

"There is certainly some risk, because this will be largest battery installation in the world by a significant margin," Mr Musk said in Adelaide on Friday."

Link: http://www.bbc.com/news/world-australia-40527784

Typical predicted shortfall in supply is 300 MW. here for example is what the energy overseer predicts for the next couple of years. You do the maths with a 100 MWh battery

Cheers

Greg Locock


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Greg... looks like you need three or four of them...

Dik

I /think/ that graph is the average power draw over a 24 h period, in which case a 100 MWh battery is not even going to make a dent in the shortfall.

Cheers

Greg Locock


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Isn't the point of the battery just to carry things long enough to get some big generators up and online or as carry thru cuz a cloud passed over a large solar array? In that case you can suck 500MW out of a 100MWhr battery for a short while. The size of the battery just offers the dispatchers more options ranging from do-nothing ride-throughs to crank up a coal plant.

Keith Cress
kcress - http://www.flaminsystems.com

That'd be OK if they just had an intermittent power problem, but they actually have a baseload problem, if the wind doesn't blow. Well, as it happens the Dear Leader is renting several truckloads of diesel generators.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Yes, think of it as a big 'UPS system' which may allow the grid operators to manage a more graceful shutdown and/or isolation of critical infrastructure.

It could also limit the impact of 'brownouts', which those of us living here in SoCal can vividly remember from 2000/2001, when our state's power grid was being manipulated by the illegal actions of Enron, in an attempt to boost the 'cost' of electricity so as to unfairly cash-n on a 'crisis' that they had created:

https://en.wikipedia.org/wiki/California_electrici...

John R. Baker, P.E. (ret)
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JohnRBaker:

Funny, that's the way I considered it... Their problem is systemic and I think of this as a tiny bandaid.

I think it actually does deal with one specific systemic problem; when generators go down, the latency for the network to compensate for the step change can often lead to even worse cascade failure problems. A battery system could possibly allow the system to transition less abruptly, thereby reducing the risk of catastrophic cascade failures. The US has experienced a few instances where a single failure caused ripple effects over an area 10x the size of the area of the original failure.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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In today's WSJ
https://www.wsj.com/articles/how-energy-rich-austr...
They have a weak national grid and pipeline system, they allowed gas to become the primary generation fuel with no storage requirements, and they didn't plan at all.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

But Al Gore says the lithium ion battery will solve it. She'll be right, mate.

The interconnectors are rated at 600 MW (roughly). It was when they bombed out due to overload that the system black cascade really got going. So any intermittency handler has to cope with a 600 MW draw. Mr Musk's Magic Machine gives a 10 minute breathing space. I don't know how long it takes to get a non spinning reserve up to 600 MW. What they should be doing is using the interconnector load as an indicator to bring in non spinning reserves, rather than relying on it running at 100% as it is a cheap source of baseload.

Cheers

Greg Locock


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Musk is not the only player in the emerging 'energy storage' market. It's starting to attract some truly big players:

AES and Siemens create joint-venture for energy storage

http://www.reuters.com/article/us-aes-siemens-batt...

John R. Baker, P.E. (ret)
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Irvine, CA
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The secret of life is not finding someone to live with
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This is my favorite storage, if you have mountains
http://www.aresnorthamerica.com/

They are talking about 2GW x 8hrs, and trains are a well established technology.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

Need a lot of train cars to store the equivalent of even a small pumped storage lake. Should be more efficient though.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

Round trip efficiency of the 1960s pumped storage in Wales was around 73%. Ain't gonna beat that with a railway.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

I read in one of the referenced items that they're looking for about an 80% efficiency.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
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I'd expect train storage to be way more efficient than pumps. A lot faster to reverse too. Interesting! I wonder if they're filling them with lead or something else heavy.

Keith Cress
kcress - http://www.flaminsystems.com

I must have blown past the part where energy was required at some point to get the cars back UP the hill.

Before I watched the video, though, I was trying to imagine how a system like this would work. I was imagining box cars full of water, running downhill in the same fashion as the video. However, in MY version, I imagined them emptying the water at the bottom of the hill so the cars would be significantly lighter to pull back up the hill. How are the cars filled with water, you ask? Snowfall at the top of the mountain. Getting the snow to melt for space efficiencies wasn't quite worked out in my plan yet.

Dan - Owner
http://www.Hi-TecDesigns.com

Top of hill is coal mine. Bottom of hill is coal fired power plant. Neat.

It's Runzoni...

Runzoni downhill...

Dik

The idea is not to create energy, it's to store excess wind & solar energy and then make it available when the sun don't shine and the wind don't blow. There are not than many locations where pumped storage is possible and then you have to build dams, flood valleys, deal with droughts, floods, and fish kill etc. This would work anyplace you have a hill. But every car has it's own MG set and you would need tens of thousands of them to store meaningful amounts of energy. Looks very expensive to me.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

The videos that I saw were using large blocks of concrete as the 'ballast'. And these so-called 'railroad' cars were purpose-built for this task, each with their own electric drive and regenerative 'braking' system, and were attached to a 'third rail' where the power would be transferred, both when it was going up and then while coming back down the long grade. Also, there were what looked like hundreds of these 'rail-cars' setting on parallel tracks, and of course the whole thing was intended to be operated automatically, running the 'cars' up the grade when excessive power was available from the grid and then letting them roll back down when there was a need to supply additional power back to the grid.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
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The secret of life is not finding someone to live with
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The loop efficiency of EVs storing regen braking and then using it again is normally quoted as 60%. There are good reasons why that figure is low, and I think 80% would be achievable. The interesting thing about 'free'-ish energy is that efficiency in the normal engineering sense doesn't matter, bang per buck is far more important.

For instance a wind generator that is only 80% as efficient at extracting wind energy as a competitor that costs 30% more is actually going to make more sense.

Cheers

Greg Locock


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Greg,

60% would be for regen braking charging a battery or supercapacitor, then discharging it through the motor when the energy is used, correct?

Whereas the grid-connected storage concept does not have the battery/capacitor charge/discharge step, with its associated losses.

You don't need many MG units, as each can haul a number of loaded cars.
If you wanted to you could limit the total number of cars by unloading at the top and sending empty cars back down for another trip.
Just like with pumped storage the cost/eff of the initial 'charging' is irrelevant, the power is worth zero anyway since there is no other use for it. Storing as much as possible, and being able to recover it on demand is the issue. And to scale up you need rail cars and rock, not too hard.

I love supercapacitor talk, since the max recoverable power is 50%. It isn't hard to beat that.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

The video showed each car with a MG and said they used 800 cars for the small pilot project so I don't think they are sending them up or down empty but that would increase capacity. You would need twice as much track for two way traffic but that would be a minor cost.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

It's not uncommon for locomotives to be weighed down with concrete to increase tractive effort now.

Tank cars might be a little better than box cars for liquids, but loading and unloading would eat into operating the trains.

Question is if this would be an AC system or DC system requiring an inverter. And if it is an AC system, would you have three collector rails?

Also what is the cost of replacing wearable parts?

They mentioned 'third rail' and not 'rails' so I'd guess DC. Also I could see where a small-ish battery bank could reduce sags and the discontinuities between generating and storing. DC would allow a pretty standard VFD style DC bus with batteries as the buffer. Running DC also avoids all the speed/frequency issues.

Keith Cress
kcress - http://www.flaminsystems.com

The power cost is very large factor in the overall econimics of storage. While there may be a few hours a year of zero cost(or even negative cost) power, a more typical daily swing on the USA west coast is $15/MWhr off-peak and $35/MWhr on peak.

I don't know if I'm repeating myself, here's an invaluable source of data on the Australian energy market. I've linked to the instant view, but there is a lot of data in the other tabs there

https://www.aemo.com.au/Electricity/National-Elect...

Over the past couple of days the price paid per MWh went from $74 to $268 in NSW. At one point in SA it was -$545

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

I've just caught up with the links to the ARES Rail Energy Storage Scheme. My first thought was to check the calendar - but no, it's not April 1. Then I wondered why on earth you would consider this over technologies such as Pumped-Storage Hydro?

Thinking about it, though, I guess I can see the logic in the right circumstances - the technology would work where you have limited gradients (steel-wheel-on-rail doesn't work well on steep grades), plenty of horizontal space but limited elevation to play with, limited amount of energy storage requirement - and no suitable water / dam sites.

However, where there is a suitable elevated water storage site above a lower pond, it is hard to see how this technology could compete with Pumped-Hydro for capacity (scale) or efficiency.

E.g. the Ares Nevada project is looking at 50 MW / 12.5 MW.hr capacity (15 minutes storage at full capacity). Existing Pumped-Storage schemes are already in the multi-GW range, with tens of GW.hr storage (i.e. able to run at full capacity for hours, not minutes), and with round-trip efficiency > 80%.
https://en.wikipedia.org/wiki/Pumped-storage_hydro...

http://julianh72.blogspot.com

JH, there are also many places in the world where water is simply not available, and if there isn't already a dam with a power house nearby there is that cost also.
I just think that ARES is a cleaver way to look at things. Use existing well proven technologies and rearrange them.
Scaling up to a few GW and 8-12hr run time is just a matter of more stuff, not new tech.

I have seen the 80%+ number sited for PHES many times, but I have never found the original analysis. The only ones that I have found assume that the original electrical power is free, a stranded resource, and they only account for the hydraulic energy. Even then I find it hard to believe that a motor-pump-pipe-pipe-turbine-generator would only total 20% loss.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

Where pumped hydro was built in conjunction with a nuke plant to provide nighttime load for the nuke plant the input power may have been assumed to have a lower cost than free.

@EdStainless:

Re: 80% round-trip efficiency for pumped-hydro storage - believe it, the figures are real, and proven many times, over many operating plants.

Hydro-electric generation efficiency runs at over 90% for large scale plant http://www.mpoweruk.com/hydro_power.htm and large electrically-driven pumps can achieve similar efficiencies, but there is a slight loss of round-trip efficiency for a system which has to operate in both generating and pumping modes. Frictional losses are small in a typical plant, because the penstocks are usually kept quite short (e.g an ideal plant has the upper and lower storage ponds very close to each other, with the plant located directly below the upper storage), and flow velocities are kept within manageable limits.

Of course, there's still the cost of transmission to / from the grid (a lot of the most efficient schemes look to co-locate the storage near the intermittent generation plant), O&M costs, costs of capital, etc, but for energy efficiency when you need to store a few GW.hours of electricity, there's not much that can touch pumped-hydro at the moment.

http://julianh72.blogspot.com

And as for the assumption being that the source power is free - the whole idea of storage is to store energy when it is available at lower cost / greater supply than the demand, and release it when the demand exceeds the generating capacity. Benefits include the ability to capture fluctuating energy sources (wind and solar for example), run thermal plant at design rating (when it operates at maximum thermal efficiency) 24 / 7, rather than running at reduced rating / reduced thermal efficiency at times of lower demand, etc.

Also - don't underestimate the capital benefits of reducing the amount of installed base-load generating plant that you need to build. It can be much more economical to build and run 1 GW (say) of base-load plant continuously (operating at maximum thermal efficiency), together with 0.5 GW of storage (say) to account for the peaks, rather than building 1.25 GW of base-load plant, and cycling it from 0.75 to 1.25 GW to match demand.
(Made-up numbers, just used to illustrate a point.)

http://julianh72.blogspot.com

Desperate times in Adelaide.

http://www.adelaidenow.com.au/news/south-australia...

The link didn't work for me so I googled

south-australia/diesel-generators-promised-in-plan-to-save-sa-from-summer-blackouts-cant-run-at-full-power-on-hot-days/

output degradation due to ambient conditions should be known to the power company, the reporter just seems to sensationalize their "discovery".

http://www.adelaidenow.com.au/news/south-australia...

is a better link. Quite why news.com.au is annoying everybody with their silly subscription paywalls is beyond me, since they also offer a mechanism to circumvent it.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

byrdj,
You have to expect sensationalism from the press. That's what they do.

But the story continues to be that South Australia is in dire straits because of their dependence on renewables, and their failure to plan. Thus they have to depend on measures like diesel generators, not the preferred option for generation for big cities.

YES, I was narrow sighted in my comments. I see their dire straits. AND I have a gut feeling the US is not far behind.

the phrase diesel generator is misleading. they appear and reported to be Combustion TURBINEs, that will be intially fuel with diesel. this types of units are being extensively built in the US. they could add a boiler to the exhuast and a steam turbine and have a very popular plant arrangement

Whatever temporary measures they adopt, it was all avoidable. Australia has plenty of coal and gas, but there is green resistance to using coal fired generation, and green resistance in the southern states to more gas production in their backyard. So when the wind doesn't blow and the sun doesn't shine, they have power shortages.

Here's an item about grid-connected batteries which includes a mention of the South Australia power issues:

https://seekingalpha.com/article/4098547-grid-conn...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

Elon Musk has completed his first major battery project in South Australia:

Tesla Delivers the World’s Biggest Battery—and Wins a Bet

CEO Elon Musk had set a 100-days-or-it’s-free deadline for completing the Australian project

https://www.wsj.com/articles/tesla-delivers-the-wo...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

I wonder why the Greens would resist using coal fired generation?

Dik

I still remember fondly Geo Bush jr's plan to reduce emissions by "Sequestering coal".
The text of that speech was on the White House web site.

Bill
--------------------
"Why not the best?"
Jimmy Carter

green's believe coal fired generators are dirty, particulates I think are the worst; and I suspect they think "clean coal" is an oxy-moron.

SA's problems are not founded in an inability to plan, but rather in their ability to believe in their plans and their predictions, and themselves.

another day in paradise, or is paradise one day closer ?

If it's not GREEN then it must be DIRTY.
Coal causes CO2 emissions. That's not green so it must be dirty.

Bill
--------------------
"Why not the best?"
Jimmy Carter

Today it was announced that the SA government has bought (as opposed to leased) the diesel fuelled backup generators that have just been installed. All hail the green revolution.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Well them babies will fill in quickly!

Didn't Musk just get a battery leveling system installed in SAus?
Ah, here it is:
Musk-beats-deadline-building-worlds-biggest-battery



And what happened with the Train-battery?

Keith Cress
kcress - http://www.flaminsystems.com

Much easier to be "green" when you're warm or cool as the season demands, and comfy :)

The problem with sloppy work is that the supply FAR EXCEEDS the demand

Musk's battery will keep things going for 20 minutes if the interconnector goes down again. I'm not saying it's a bad thing, but it isn't even the icing on the cake, it's the sprinkles on top of the icing on the cake. Ideal political solution really, doesn't cost much, doesn't do much, sounds cute. If there was a very temporary interruption they may be able to provide a stable synchronous source so the windmills can get back onto the grid. Batteries are good for that. AEMO still predict outages starting from Jan 16 2018.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Good points Greg.

I'd forgotten the monster blackout was actually caused by dropped lines and not some short-tern shortfall.

Keith Cress
kcress - http://www.flaminsystems.com

It may be possible to 'pull everything non essential off' to extend the battery a bit...

Dik

The battery would also allow for the controlled shutdown of interruption-sensitive systems as well as providing time for organizations like hospitals and other emergency providers to switch seamlessly to standby generators.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

dik, well let's see, yesterday SA peaked at 2200 MW demand. Musk battery is good for around 100 MW for one hour. The interconnector is around 700 MW. I guess every little helps, but it certainly isn't overkill.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Such a battery could soften the load shedding, which often is worse than whatever initially causes a power interruption.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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FYI
from the BBC, "The 100-megawatt battery, built by Tesla, was officially activated on Friday. It had in fact provided some power since Thursday due to demand caused by local hot weather."

link: http://www.bbc.com/news/world-australia-42190358