Slashdot Mirror
Tesla Big Battery Outsmarts Lumbering Coal Units After Loy Yang Trips (reneweconomy.com.au)
The Tesla big battery is having a crucial impact on Australia's electricity market, far beyond the South Australia grid where it was expected to time shift a small amount of wind energy and provide network services and emergency back-up in case of a major problem. From a report: Last Thursday, one of the biggest coal units in Australia, Loy Yang A 3, tripped without warning at 1.59am, with the sudden loss of 560MW and causing a slump in frequency on the network. What happened next has stunned electricity industry insiders and given food for thought over the near to medium term future of the grid, such was the rapid response of the Tesla big battery to an event that happened nearly 1,000km away. Even before the Loy Yang A unit had finished tripping, the 100MW/129MWh had responded, injecting 7.3MW into the network to help arrest a slump in frequency that had fallen below 49.80Hertz.
For the benefit of Americans reading: the nominal AC frequency in Australia is 50Hz, not 60Hz.
The resiliency of the power grid would be vastly improved if we put a battery pack (the size of a normal intermodal container) at each substation. These could act like your home UPS, fixing blackouts of a few minutes, when they occur. This also would make the grid much more able to use wind and solar sources, without so much need for standby diesel systems currently in place.
When is Musk going to stop making big promises and then following through?
He sure is a bad politician.
Trying to remember why it wouldn't have worked. Because it might steal their market share? Yeah pretty sure that was their reason they didn't think it would.
They are both affected. But power companies will let the voltage drop while holding frequency as close to theoretical as they can. They even run 0.1 Hz high or low at the end of the day to get the correct number of cycles for the period.
If you've ever designed a power supply, you'd see that you must accept low/high voltages, but should expect the frequency to be fairly steady.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
If a power source goes offline, wouldn't you see a slump in voltage? Why the decrease in frequency?
In DC, yes. AC is a different animal. The AC frequency is determined by the speed of the generators. When demand outstrips the supply, the generators slow down. Therefore, the frequency drops.
You would likely see a drop in voltage too. However, AC voltage is difficult to measure. Frequency is a much more precise way to measure the status of the grid.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
UPS, that's not a UPS,
THIS is a UPS!
hehe
L'Idiot
The grid worked as designed. News at 11.
Steam plants don't come online in 6 seconds, they just don't.
First the UPSs, then load curtailment, hydro and combustion turbines, finally the steam plants and steam parts of combined cycle plants.
The real point (beyond the usual /. 'Ol Musky' blowing) is that apparently Australia was in spinning reserve violation when this happened. Your supposed to have enough power spinning to cover you single biggest unit/transmission line falling over (as they say in Australia).
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
Good question. A simple way to view it is that the grid is powered by generators. The generators are built to run at a fixed speed, and are wound so that the fixed speed outputs (in this case) 50Hz at a fixed voltage. The voltage output of the generator is a sine wave and it will lead (since it's generating) the grid voltage by a small amount (lead means same frequency, slightly ahead of phase). The amount it leads determines the load, and the generator has a limit to how much load it can handle, so if you tried to speed it up by turning it faster, it would start to lead slightly more and the load would increase (more current, but more resistance to the prime mover turning the generator) so the speed stays close to 50 Hz and it only speeds up a very small amount very briefly. When you drop a bunch of generation offline, the rest of the generators see a bunch more load suddenly, which is felt as a physical torque, so the generator gets harder to turn. The prime movers (turbines typically) can't produce more power instantaneously so the generators start to decelerate slightly. That's why you see the grid frequency drop slightly until the turbines increase power to take up the load. That's assuming the remaining generation can handle it. What they're saying here is that the Tesla system, since it uses inverters, can respond faster than the turbines generating power (duh). I'm not sure why it's described as shocking. Near where I live, in Canada, they installed a few MW of magnetic bearing sealed-vacuum flywheel energy storage specifically for frequency regulation due to all the new windmills they installed. The flywheels are spinning at synchronous speed and can absorb and deliver energy to the grid as needed, similar to the Tesla battery system.
"I have never let my schooling interfere with my education." - Mark Twain
...where it was expected to time shift a small amount of wind energy and provide network services and emergency back-up in case of a major problem.
No, the primary purpose of the battery was to help the grid ride through transients just as the one described, not for time shifting. Who is writing this stuff?
"So I'll bite, why would there be enough advantage to a space-based solar array to offset the problems that a space-based solar array would have over a terrestrial solar array?"
Sure, since the power would have to be sent as microwaves down to earth, you could grill little rocket man or some other nuisance.
And the ability to roast anyone unlucky to be in the beam path.
The narrative and conclusions are a big dodgy. Everybody knew beforehand that batteries can jump in immediately to supply power. And the batteries did not stop a complete collapse, electrical networks are thoroughly analyzed and simulated and braced against major consequences if any one unit trips out. Major outages are quite rare over the decades, and all done without a single battery. Gas turbines can come on-line within 60 seconds and other interconnected plants often have enough reserve capacity to tide over small outages. Batteries are welcome as an immediate source, but they are still awfully expensive and awfully small in GWH.
And "What happened next" did not stun electricity industry insiders. It was engineered to do the very thing it did.
If you've ever designed a power supply, you'd see that you must accept low/high voltages, but should expect the frequency to be fairly steady.
Most power supplies I've seen, and made, will accept anything from below 50 to above 60Hz. The frequency is pretty much irrelevant as long as the transformer (for a linear) is still efficient enough. Now that most of them are switchers, they'll even take anything from about 90 through 240V, and some of them are quite happy running off of DC.
Grid level power management is utterly unlike your home UPS.
I think the article is overstating a bit given the scale, but the macro implications are impressive. Grid-scale generators are slow to ramp up and down - minutes to hours (or even days for startup of nuclear plants). Small, less efficient generators handle the small peaks (oddly enough, called peaking generator) that go beyond baseline generation and any under-utilization goes to waste so it's a careful balancing act. And even the peaking generators aren't instant response whereas the Tesla Battery IS essentially able to go from 0-100MW in moments (they should advertise this along with the Tesla speed records). This allows highly efficient supply of peak-demand (or, in this case, unexpected demand) which is pretty much unheard of.
Having 500MW go offline suddenly does Bad Things to the overall grid. Remember when one plant tripped offline ... I think in upstate NY and blacked out most of the northeast in a cascade failure several years back? Having something able to take a near-instantaneous load, even for a few minutes, is a massive benefit.
You can get rich if you own a politician, but you have to be rich to buy one in the first place.
The coal plant that failed was producing close to 600MW. The max output from the graph in the article showed the battery system inject less than 10MW max into the grid. Who pickup up the other 500+ MW? The other coal plant that came online within 6 secs. Basically all the batteries did was reduce the size of the brownout.
The "spinning reserve" generally picks up the demand. "Spinning reserve" consists of machines which are on the grid but not at full load. The spinning reserve should be a minimum of the sum of the largest individual generator + the maximum estimated demand change that could happen in around 10 minutes (the time it takes for a gas turbine to start up). Generally, all that is necessary to change spinning reserve into real power is for a valve to be opened further. For combustion or steam turbines, this can occur in less than a second, and is automatically controlled by the generator controller - the generator demand signal will increase as grid frequency decreases. Spread across many generators, the increase in output is not a significant shock to any individual generator.
In this case, it seems that the Australian grid did not have adequate spinning reserve, which is why the frequency dropped. Many power stations are set to shut down in the case of large frequency variations (for machine protection), which caused the coal power station to shut down.
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
Because insiders know how rare it is for something to do what it's supposed to do?
Why guess when you can know? Measure!
The drop in frequency itself isn't the big problem, it's a gauge, an indicator.
The frequency tells you how fast the generators are turning. They are automatically throttled to try to spin at the right speed to produce 50Hz. If they aren't producing 50Hz, that means they are full wide open throttle and still can't keep up. It means they can't produce enough power.
Space array:
No reality, not feasible, 100% vaporware.
Will never happen. Ever.
https://dothemath.ucsd.edu/201...
PS: Anything that claims to be 100% predictable is not engineering, is not based in reality, and is bullshit.
There are exactly zero other systems that approach this size and scope. That's the reason for the story.
This is the world's biggest grid-connected battery, and it works as advertised, if not better. It may be particularly craven of me, but that seems to be rare with infrastructure projects these days.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
Actually, no, it wasnt engineered to back up a power plant in Victoria, it was engineered to back up power in South Australia. There was an entirely different coal power plant that was supposed to back up Loy Yang (which is one of Australia's largest) - a plant that ratepayers have to pay to keep running on standby, which is supposed to hold the grid up until downed power plants can be brought back up and/or more baseload elsewhere ramped up. But from nearly 1000km away, the Tesla battery did the standby plant's job for it during its 4-second wakeup time - stopping and reversing the decline in grid frequency so that there wasn't even a meaningful blink in power quality.
This is not what the Tesla battery was designed to do. It was designed to deal with situations with downed lines / plants in South Australia, to keep the lights on there. It wasn't supposed to take over the work from standby plants halfway across the country. That it technically can should surprise nobody. But that's not what it was purchased to do.
"This wallpaper is killing me. One of us has got to go." -- Oscar Wilde on his deathbed
And "What happened next" did not stun electricity industry insiders. It was engineered to do the very thing it did.
But we're talking coal man, the energy of the future! If those old fashioned batteries have to kick in to replace coal's failings, how is coal ever going to show it's superiority? I'll just show myself out now.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
It is likely a linear power response to frequency with a small dead band.
In the UK, battery backed frequency response is an important contributor to frequency stability, and is operated with a dead band of 0.015 Hz. The power injection is required to be proportional to the frequency deviation from outside the dead band, reaching 100% rated power at 0.5 Hz deviation from nominal. Response time is a maximum of 1 s.
Additionally, in the UK, the requirement is that the frequency response is symmetrical. If frequency rises, then the system must absorb power - up to 100% of maximum rated power at 50.5 Hz, for a minimum of 15 minutes.
Yep, that is one of the major features. Who doesn't want an orbital death ray at their command?
That said, it's only really an issue if you intentionally design the array to be able to focus the beam much more tightly than normal power transmission designs call for - typical designs call for receiving antennas several square miles specifically to avoid that problem, keeping transmitted power densities on par with normal sunlight.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
If you were to trace back the history of the grid issues this region of Australia has been facing, you'd find that the actual blackouts and brownouts they have been suffering come after faults or other sudden disturbances.
Its a bit complicated, in that the stress on the grid can be greater if demand is high and local wind is not producing. That is when the likelihood of a fault or sudden event will bring down a part of the grid is greatest. In that sense, the batteries offset low renewable production. But still, the primary thing that maintains reliably is the fast response voltage and frequency support.
Came on line? I assure you the backup was ALREADY on line, steam in the boiler with the generator turning in sync with the mains.
What it wasn't doing is pushing out power. Somebody or something has to advance the throttle to make that happen and apparently that takes about 6 seconds.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
I guess to be more complete, I should also add that when generation drops offline, but load is the same, then grid voltage *will* drop in the system, but the amount it drops is complicated. Every point in the system has a different voltage. The voltage drop causes more current to flow from the remaining generators, which is load, which causes them to slow down, hence the frequency drops a bit. The frequency drop is directly related to generator speed, and the generators are speed regulated so the control systems try to speed them back up by dumping in more fuel (if coal or gas). Also, when the voltage drops, that automatically sheds a small amount of load: resistive loads like incandescent lights and heaters draw current proportional to voltage, and some UPS equipment will detect the brown-out and switch to battery. However, there's voltage regulation built into the grid (in the form of variable transformers) so those will attempt to adjust for the lower grid voltage by changing their winding ratio to compensate, so in general the load stays fairly constant. From my understanding you generally model an industrial load (like a factory) as a constant power load in kW, *not* a constant current draw in amps or a constant resistance/impedance, so if the grid voltage falls, from your point of view as a fixed output voltage generator, the grid just consumes more current.
"I have never let my schooling interfere with my education." - Mark Twain
Demand and supply upsets are presented mostly via deviation from ideal frequency. When there is a slow increase in demand it can present loads on generators and overloads in this scenario is what causes those generators to trip on overload. The energy market can predict these loads quite adequately and the national regulator makes requests of the generators to intervene appropriately. The grid is stable because it can be predicted for small loads (people in large groups tend to do the same thing day after day), and for large loads the suppliers needed to be contacted (e.g. we needed to call the provider every time we wanted to start our 20MW compressor)
During a grid upset i.e. a major load suddenly starting or stopping without warning because something tripped, caught fire, etc, what you see is the generators with massive amounts of inertia taking their time to change. A large coal fired turbine could take several minutes to ramp up steam power to continue to spin at the same speed, likewise with ramping down. A small gas turbine can do it in a matter of several seconds. During these time there is a frequency fluctuation across the grid. If that is serious enough the grid could destabilise to the point where protection systems kick in and trip off the generators. This is needed because frequency response is generally much faster than power based responses for machinery protection.
We had a similar such event when our provider tripped an upstream substation and didn't send us an intertrip signal. Our pathetic little 40MW of generating power suddenly was left trying to power 2 suburbs, a refinery, and a busy international airport. There the turbines suddenly got really loud and tripped less than a second later on under-frequency. Had we had a reasonable size battery chances are we would have ridden through until the battery started failing and then tripped on overpower.
To get to the point: The Tesla battery will do a few things: 30% of it's capacity is dedicated to frequency management, likely control around 50Hz with a small deadband. The remaining 70% is on energy demand and lags much further behind (probably responding within seconds rather than milliseconds) and this is likely under the control of the national energy market as to when it comes in and doesn't.