What Is "Induced Atmospheric Vibration"?(physics.stackexchange.com)
physics.stackexchange.com
What Is "Induced Atmospheric Vibration"?
https://physics.stackexchange.com/questions/848666/what-is-induced-atmospheric-vibration
16 comments
Reactance is such a beautiful French word...It just reminds you of some frustrated romantic attempts in a Paris scenario. :-)
But your electrical supplier will charge you for it. Had a electrical power teacher with a past employment at a power supplier, who sadly loved to brag how he used to terrorize small farms when their own power generators had a cos φ below 0.98. I think the rule for Portugal is cos φ above 0.97 and for Spain 0.95 also known as el coseno de phi...
"Cos-phi compensation" - https://fortop.co.uk/knowledge/white-papers/cos-phi-compensa...
But your electrical supplier will charge you for it. Had a electrical power teacher with a past employment at a power supplier, who sadly loved to brag how he used to terrorize small farms when their own power generators had a cos φ below 0.98. I think the rule for Portugal is cos φ above 0.97 and for Spain 0.95 also known as el coseno de phi...
"Cos-phi compensation" - https://fortop.co.uk/knowledge/white-papers/cos-phi-compensa...
Wonder how much complexity using AC adds to this? With DC you would not have to worry about frequency and phase matching. But then you need to convert the DC back to AC at some point.
I think the contrary is true. Frequency and phase matching is a feature, not a bug. Because AC gives you frequency, and frequency is not just easy to measure but also easy to have accurate references and very immune to noise, it is also not influenced by step-up/step-down transformers. This makes balancing an AC grid possible. Frequency below the set point? Increase power output. Frequency above? Reduce. As an added bonus, this happens to exactly match up with how synchronous generators work. So you get a fairly robust way for many distributed power plants to collectively coordinate power output without additional communication just by agreeing on the physical quantity which we can measure with the highest precision of any quantity very cheaply.
That is not possible with DC.
That is not possible with DC.
Bingo! So many people miss this.
(Efficient) High voltage AC is ‘easy’ due to how well transformers work, how durable they are, and how simple they are. AC does have issues with inductive loss when buried (or near anything conductive), however. For the same reason Transformers work and are awesome.
High voltage DC is hard as it requires solid state components which are expensive to make, and prone to blowing up (aka relatively fragile). AC to DC and vice versa also adds non-trivial losses.
High voltage DC (to a first approximation) doesn’t suffer from inductive losses however, which makes it much more efficient when near conductive stuff like the ground or seawater.
It’s also ‘simpler’ (doesn’t have things like phase or frequency) which is convenient if doing things like transferring power between two power grids with dissimilar frequencies or phase.
They each have their place.
High voltage DC is hard as it requires solid state components which are expensive to make, and prone to blowing up (aka relatively fragile). AC to DC and vice versa also adds non-trivial losses.
High voltage DC (to a first approximation) doesn’t suffer from inductive losses however, which makes it much more efficient when near conductive stuff like the ground or seawater.
It’s also ‘simpler’ (doesn’t have things like phase or frequency) which is convenient if doing things like transferring power between two power grids with dissimilar frequencies or phase.
They each have their place.
>They each have their place.
Funny enough, AC+DC (hybrid transmission) on the same lines is active research.
https://electrical-engineering-portal.com/download-center/bo...
https://www.ornl.gov/content/hybrid-acdc-laboratory
Funny enough, AC+DC (hybrid transmission) on the same lines is active research.
https://electrical-engineering-portal.com/download-center/bo...
https://www.ornl.gov/content/hybrid-acdc-laboratory
I believe high voltage DC also does not suffer from skin effect. Meaning that the current is transmitted through the whole conductor, not just the surface, leading to less material needed for the same current rating.
The skin effect is frequency-related, with higher frequencies resulting in a thinner "skin". The grid frequency is low enough that it doesn't really play a huge role: a 1000mm2 aluminum conductor has a 10% higher resistance at 60Hz AC compared to DC.
One thing to remember is that it is common for the conductor to have a strengthening core: this allows operation at a higher temperature (which means a higher current), and it allows for a longer distance between support towers (which means lower construction costs). If you're going to put some poorly-conducting steel or carbon fiber in the center of the conductor anyways, why worry about the skin effect?
Besides, those conductors are massive already. At the highest voltage levels, a single set of conductors is carrying multiple gigawatts of power. Even if it were technically viable, would you want to build a single 16GW connection? If it fails, you're going to have serious trouble compensating for that - it's probably wiser to build it as 4x 4GW connections.
HVDC also has its own issues with converter losses and not being able to easily step down to lower voltages. It's very nice for distances in the hundreds of kilometers, but it's just not a viable alternative for short city-to-city links.
One thing to remember is that it is common for the conductor to have a strengthening core: this allows operation at a higher temperature (which means a higher current), and it allows for a longer distance between support towers (which means lower construction costs). If you're going to put some poorly-conducting steel or carbon fiber in the center of the conductor anyways, why worry about the skin effect?
Besides, those conductors are massive already. At the highest voltage levels, a single set of conductors is carrying multiple gigawatts of power. Even if it were technically viable, would you want to build a single 16GW connection? If it fails, you're going to have serious trouble compensating for that - it's probably wiser to build it as 4x 4GW connections.
HVDC also has its own issues with converter losses and not being able to easily step down to lower voltages. It's very nice for distances in the hundreds of kilometers, but it's just not a viable alternative for short city-to-city links.
Yes, one of the biggest cons (in practice) with DC is the lossy and fragile voltage regulation (both up and down). It is a far simpler form of power delivery though, for better or worse.
AC is amazing for that due to the ease of making/using transformers, as well as efficiency in situations with simple spinning motors, and due to the way it behaves is ‘more safe’ in a number of fault condition.
AC is much easier to manage with fault protect as it has a zero volt crossing point each cycle, and safer for humans from a shock/electrocution hazard perspective due to the reversing voltage/zero crossing point. Muscles won’t ’freeze’ in a given position like with DC, but rather spasm (though it can be so fast it’s basically the same thing), and the zero voltage crossing point tends to allow arc self extinguishing at much lower thresholds.
But the same thing that makes it much easier to voltage regulate (using transformers) is also what creates inductive losses and complicated in some other scenarios (like conversion to DC for non-motor loads, PF issues, etc.).
No one needs a bridge rectifier for a DC to DC power supply, for instance, and DC to DC ripple is dramatically easier to deal with than typical half phase residential AC.
Commercial can have the luxury of 3 phase AC at least, but that is also typically at power levels that it still isn’t going to be cheap building a AC to DC power supply. And god help that power supply if you get phase imbalance.
AC is amazing for that due to the ease of making/using transformers, as well as efficiency in situations with simple spinning motors, and due to the way it behaves is ‘more safe’ in a number of fault condition.
AC is much easier to manage with fault protect as it has a zero volt crossing point each cycle, and safer for humans from a shock/electrocution hazard perspective due to the reversing voltage/zero crossing point. Muscles won’t ’freeze’ in a given position like with DC, but rather spasm (though it can be so fast it’s basically the same thing), and the zero voltage crossing point tends to allow arc self extinguishing at much lower thresholds.
But the same thing that makes it much easier to voltage regulate (using transformers) is also what creates inductive losses and complicated in some other scenarios (like conversion to DC for non-motor loads, PF issues, etc.).
No one needs a bridge rectifier for a DC to DC power supply, for instance, and DC to DC ripple is dramatically easier to deal with than typical half phase residential AC.
Commercial can have the luxury of 3 phase AC at least, but that is also typically at power levels that it still isn’t going to be cheap building a AC to DC power supply. And god help that power supply if you get phase imbalance.
That's easy enough to say but big iron power electronics are orders of magnitude more expensive than copper windings and magnetic steel laminations , both in terms of capital cost and maintenance. It's also dramatically harder to extinguish DC arcs so switching gear and substations need more expensive designs as well. The grid could not exist at present, let alone 100 years ago, if we operated it all DC. Over time more and more of it will shift to DC, particularly for long haul, but AC has enough advantages that's it's unlikely to ever go away.
I'm short, it's this way for a reason. The complexity is nessessary.
I'm short, it's this way for a reason. The complexity is nessessary.
Some parts of the energy transmission grid are DC, but looks like it's mainly international, undersea, and long-range transmissions: https://en.wikipedia.org/wiki/High-voltage_direct_current
And only because long-distance transmission is more efficient.
I imagine AC makes things considerably more difficult. Reactance is a consequence of inductance and capacitance, which cause current and voltage changes to be out of phase with each other. While the current on a DC transmission line will vary, it will not be reversing every ~10 milliseconds, and I suppose the voltage will be very steady except during startup and shutdown.
On an AC transmission line, I suppose any corona discharge going on shuts off and restarts every time the voltage reverses. They make a characteristic buzz in humid conditions.
On an AC transmission line, I suppose any corona discharge going on shuts off and restarts every time the voltage reverses. They make a characteristic buzz in humid conditions.
[deleted]
All of it, I guess. That phasor is always complex.
Ha, I was waiting to see a comment with the obvious pun to be made here. :)
For non-physicists: https://electronics.stackexchange.com/questions/128986/why-u...
For non-physicists: https://electronics.stackexchange.com/questions/128986/why-u...
> Wonder how much complexity using AC adds to this?
Summarizing a couple of year of very annoying electrical studies: Yes
You can't believe how much
Summarizing a couple of year of very annoying electrical studies: Yes
You can't believe how much
On the other hand, having a continent-scale AC grid is not just possible but common. Europe and North Africa have one, Russia has one, China has one, the US has two or three. Meanwhile multiterminal HVDC is basically experimental stuff that's only possible with real-time digital control systems.
Having a worldwide data network is also only possible with real-time digital control systems as well
The issue is one of technology (having high powered switching components only took of in the last 30? yrs or something) and legacy
(Edit: IGBTs are from the 80's though it seems the 1st generation wasn't that great, IGCTs from the late 90s https://mb-drive-services.com/experience-with-igct-based-vfd...
The issue is one of technology (having high powered switching components only took of in the last 30? yrs or something) and legacy
(Edit: IGBTs are from the 80's though it seems the 1st generation wasn't that great, IGCTs from the late 90s https://mb-drive-services.com/experience-with-igct-based-vfd...
DC comes with another 1000 problems. It wouldn’t be any better, really.
Is this why some very high power transmission lines are HVDC perhaps?
"With inverter-based power storage, generation, and transmission, the grid can now react incredibly quickly. This is good when they do the right thing, but can be very bad when they do the wrong thing."
I'm wondering if this will be like the 2016 South Australian blackout
https://en.wikipedia.org/wiki/2016_South_Australian_blackout
"AEMO identified software settings in the wind farms that prevented repeated restarts once voltage or frequency events occurred too often. "
Grid operators are currently mostly against renewable and so they impose "blunt" disconnect rules on inverters behind renewable sources, and this comes to bite the grid when the proverbial shit hits the fan.
May be in the end this will be a good thing and grid operators will start to treat inverters and renewable as a strength and modify grid regulations as needed.
I'm wondering if this will be like the 2016 South Australian blackout
https://en.wikipedia.org/wiki/2016_South_Australian_blackout
"AEMO identified software settings in the wind farms that prevented repeated restarts once voltage or frequency events occurred too often. "
Grid operators are currently mostly against renewable and so they impose "blunt" disconnect rules on inverters behind renewable sources, and this comes to bite the grid when the proverbial shit hits the fan.
May be in the end this will be a good thing and grid operators will start to treat inverters and renewable as a strength and modify grid regulations as needed.
> "AEMO identified software settings in the wind farms that prevented repeated restarts once voltage or frequency events occurred too often. "
> Grid operators are currently mostly against renewable and so they impose "blunt" disconnect rules on inverters behind renewable sources, and this comes to bite the grid when the proverbial shit hits the fan.
As a distributed systems person, this seems like a coordination/communication problem. If a single node is having repeated events, it may likely be broken and staying offline could be a better choice. If multiple nodes are having repeated events, maybe it's better for them to stay connection and do their best.
> Grid operators are currently mostly against renewable and so they impose "blunt" disconnect rules on inverters behind renewable sources, and this comes to bite the grid when the proverbial shit hits the fan.
As a distributed systems person, this seems like a coordination/communication problem. If a single node is having repeated events, it may likely be broken and staying offline could be a better choice. If multiple nodes are having repeated events, maybe it's better for them to stay connection and do their best.
Grid operators are currently mostly against renewable
As someone who moves a lot, it's always curious to me that grid operators vary so widely on this.
Some places (like where I am now), the grid operator hates renewables and especially rooftop solar.
Other places, the grid operator will actually subsidize rooftop solar because it they say it reduces the amount of generation it has to do, thus saving money on infrastructure and maintenance.
Of course, each location has wildly different climates, but the regional politics aren't that different, so I don't think it's about ideology.
As someone who moves a lot, it's always curious to me that grid operators vary so widely on this.
Some places (like where I am now), the grid operator hates renewables and especially rooftop solar.
Other places, the grid operator will actually subsidize rooftop solar because it they say it reduces the amount of generation it has to do, thus saving money on infrastructure and maintenance.
Of course, each location has wildly different climates, but the regional politics aren't that different, so I don't think it's about ideology.
It depends heavily on their market incentives. If the local power company is also in charge of the wires, less load on the wires means less cost. In a market where distribution and generation are different operations, generation only cares about whether anyone's going to buy the electricity they want to put on the wire and you saying "No thanks, I'm full" is in direct competition to their interests (and existence as a firm).
Huh? Transmission networks get directly financially rewarded for more power flowing in the form of wheeling charges. It's wild reading HN discussions of topics that I actually know about. It makes me wonder how much I can trust the discussions I don't know about.
This is definitionally "Gell-Mann amnesia" isn't it?
https://en.m.wikipedia.org/wiki/Gell-Mann_amnesia_effect
https://en.m.wikipedia.org/wiki/Gell-Mann_amnesia_effect
I know things about airplanes. The discussions here about airplanes is laughable, below wikipedia level.
Funny enough, the effect of inverters on the grid may be mitigated with a relatively simple solution: add a flywheel to the inverter-based connection farms to "fake" a turbine.
The wind or solar farm drives the flywheel and if the grid-side power starts to fluctuate, it pulls on the flywheel before the inverters feel it. You lose some total efficiency in the electrical-to-mechanical-to-electrical conversion, but get enough flywheels and maybe you don't care (because they also act as a place to store peak energy production when demand is low).
The wind or solar farm drives the flywheel and if the grid-side power starts to fluctuate, it pulls on the flywheel before the inverters feel it. You lose some total efficiency in the electrical-to-mechanical-to-electrical conversion, but get enough flywheels and maybe you don't care (because they also act as a place to store peak energy production when demand is low).
How Wind Turbines Generate Electricity
1. Mechanical to Electrical Energy Conversion • Wind Energy Capture: The wind pushes against the blades of the wind turbine, causing them to rotate. These blades are attached to a central hub, which turns a low-speed shaft. • Gearbox (in many turbines): This shaft is connected to a gearbox, which increases the rotation speed. The gearbox drives a high-speed shaft connected to the generator. • Generator: The high-speed shaft turns the rotor inside a generator. As the rotor spins inside a magnetic field, it induces a flow of electricity—typically alternating current (AC)—using electromagnetic induction.
Some turbines use direct-drive generators (no gearbox), especially in offshore installations, which reduce maintenance.
2. Power Conditioning and Grid Integration • Variable Speed Generation: Wind speed varies, so the output frequency and voltage can fluctuate. Wind turbines typically use power electronics (converters and inverters) to stabilize the electricity before it’s sent to the grid. • Inverter Role: Converts variable-frequency AC or DC from the generator into grid-compatible AC (usually 50 Hz or 60 Hz depending on the region).
3. Phase Angle and Synchronization
What Is Phase Angle? • The phase angle represents the timing difference between the voltage waveform of the turbine’s output and the grid’s voltage waveform. • For a generator to supply power effectively, it must match the phase, frequency, and voltage of the grid. • If the phase angle is off, power cannot flow efficiently and may even cause instability or damage.
Synchronization Process • Before a wind turbine connects to the grid, its inverter adjusts the output so that: • Frequency = Grid frequency (e.g., 60 Hz) • Voltage = Grid voltage • Phase angle = Aligned with grid phase • Once synchronized, the turbine can export power.
4. Ancillary Services Provided by Wind Turbines
Ancillary services are support functions that maintain the stability and reliability of the power grid. Modern wind turbines, especially with advanced inverters and control systems, can provide several key services:
A. Frequency Regulation • Wind turbines can rapidly adjust output to help balance supply and demand. • This is called primary frequency response, essential when there’s a sudden change in load or generation.
B. Reactive Power Support / Voltage Control • Inverters can produce or absorb reactive power, which helps maintain voltage levels on the grid. • This is important for power factor correction and avoiding voltage collapse.
C. Inertia and Synthetic Inertia • Traditional turbines (like in coal or gas plants) provide rotational inertia, helping to resist sudden changes in frequency. • Wind turbines, being decoupled from the grid by power electronics, don’t naturally provide inertia. • However, some advanced systems provide synthetic inertia by rapidly adjusting power output in response to frequency changes.
D. Black Start Capability • Some wind turbines can assist in black start procedures (restarting the grid after a blackout), but this is still limited and evolving.
1. Mechanical to Electrical Energy Conversion • Wind Energy Capture: The wind pushes against the blades of the wind turbine, causing them to rotate. These blades are attached to a central hub, which turns a low-speed shaft. • Gearbox (in many turbines): This shaft is connected to a gearbox, which increases the rotation speed. The gearbox drives a high-speed shaft connected to the generator. • Generator: The high-speed shaft turns the rotor inside a generator. As the rotor spins inside a magnetic field, it induces a flow of electricity—typically alternating current (AC)—using electromagnetic induction.
Some turbines use direct-drive generators (no gearbox), especially in offshore installations, which reduce maintenance.
2. Power Conditioning and Grid Integration • Variable Speed Generation: Wind speed varies, so the output frequency and voltage can fluctuate. Wind turbines typically use power electronics (converters and inverters) to stabilize the electricity before it’s sent to the grid. • Inverter Role: Converts variable-frequency AC or DC from the generator into grid-compatible AC (usually 50 Hz or 60 Hz depending on the region).
3. Phase Angle and Synchronization
What Is Phase Angle? • The phase angle represents the timing difference between the voltage waveform of the turbine’s output and the grid’s voltage waveform. • For a generator to supply power effectively, it must match the phase, frequency, and voltage of the grid. • If the phase angle is off, power cannot flow efficiently and may even cause instability or damage.
Synchronization Process • Before a wind turbine connects to the grid, its inverter adjusts the output so that: • Frequency = Grid frequency (e.g., 60 Hz) • Voltage = Grid voltage • Phase angle = Aligned with grid phase • Once synchronized, the turbine can export power.
4. Ancillary Services Provided by Wind Turbines
Ancillary services are support functions that maintain the stability and reliability of the power grid. Modern wind turbines, especially with advanced inverters and control systems, can provide several key services:
A. Frequency Regulation • Wind turbines can rapidly adjust output to help balance supply and demand. • This is called primary frequency response, essential when there’s a sudden change in load or generation.
B. Reactive Power Support / Voltage Control • Inverters can produce or absorb reactive power, which helps maintain voltage levels on the grid. • This is important for power factor correction and avoiding voltage collapse.
C. Inertia and Synthetic Inertia • Traditional turbines (like in coal or gas plants) provide rotational inertia, helping to resist sudden changes in frequency. • Wind turbines, being decoupled from the grid by power electronics, don’t naturally provide inertia. • However, some advanced systems provide synthetic inertia by rapidly adjusting power output in response to frequency changes.
D. Black Start Capability • Some wind turbines can assist in black start procedures (restarting the grid after a blackout), but this is still limited and evolving.
Different set up but same physics apply. I was called out to a cold forming press which basically was hammering an enormous load onto billets of steel to form panels for the automotive industry.
The problem on inspection: The drop press was producing inconsistent strikes, especially noticeable when working with thicker steel billets. The machine seemed to struggle during the initial drop phase, and there was an unusual amount of sparking observed near the motor’s commutator. This problem was consistent with poor commutator maintenance and misalignment or excessive vary to the variable angle brush set up.
Whilst the motor was spinning the commutator was cleaned, after shut down the brushes were replaced and adjustaded to the optimal position ensuring they’re neither advanced nor retarded. By correctly adjusting the brush angle, it restored the proper phase relationship between the armature current and the stator’s magnetic field. This adjustment improved torque production during the drop phase, reduced electrical arcing, and enhanced overall motor efficiency.
In brushed DC motors, the brush angle determines the timing of current delivery to the armature windings. An advanced brush angle means that current is supplied earlier in the rotation cycle, which can increase torque at higher speeds but may cause excessive current draw and heating at lower speeds.
Conversely, a retarded brush angle delays current delivery, potentially reducing torque and efficiency under load.
The problem on inspection: The drop press was producing inconsistent strikes, especially noticeable when working with thicker steel billets. The machine seemed to struggle during the initial drop phase, and there was an unusual amount of sparking observed near the motor’s commutator. This problem was consistent with poor commutator maintenance and misalignment or excessive vary to the variable angle brush set up.
Whilst the motor was spinning the commutator was cleaned, after shut down the brushes were replaced and adjustaded to the optimal position ensuring they’re neither advanced nor retarded. By correctly adjusting the brush angle, it restored the proper phase relationship between the armature current and the stator’s magnetic field. This adjustment improved torque production during the drop phase, reduced electrical arcing, and enhanced overall motor efficiency.
In brushed DC motors, the brush angle determines the timing of current delivery to the armature windings. An advanced brush angle means that current is supplied earlier in the rotation cycle, which can increase torque at higher speeds but may cause excessive current draw and heating at lower speeds.
Conversely, a retarded brush angle delays current delivery, potentially reducing torque and efficiency under load.
Grid operators are, as a rule, not opposed to renewables at all. They are 'opposed' to resources that do not provide frequency support and are non-dispatchable. Renewables need storage to be well behaved. As soon as we start factoring that into the build at scale the problems go away. Generators want to ignore all the inconvenient physics of power transmission networks and just want $$$ for MW. The system doesn't work if enough people operate like that.
You're completely wrong about this.
Inverters if told so can do frequency support better and cheaper than any other solutions.
No other technology can react as fast as an inverter.
See the Texas grid grid service market which is now completely dominated by GW of inverters.
https://comptroller.texas.gov/economy/fiscal-notes/infrastru...
"One solution is to connect inverters with “grid-forming” capabilities, which help mitigate this risk by limiting fluctuations outside of 60 Hz, increasing grid stability. Experts see utility-scale batteries as a prime opportunity to deploy grid-forming inverters to the grid, as grid-forming integration with batteries is cheaper and faster than building new transmission."
"grid-forming" inverter is just software and parameters, your el-cheapo home solar inverter can do it too. It currently is prevented from doing so by ... grid operator regulations which ask it to disconnect at the first issue.
Inverters if told so can do frequency support better and cheaper than any other solutions.
No other technology can react as fast as an inverter.
See the Texas grid grid service market which is now completely dominated by GW of inverters.
https://comptroller.texas.gov/economy/fiscal-notes/infrastru...
"One solution is to connect inverters with “grid-forming” capabilities, which help mitigate this risk by limiting fluctuations outside of 60 Hz, increasing grid stability. Experts see utility-scale batteries as a prime opportunity to deploy grid-forming inverters to the grid, as grid-forming integration with batteries is cheaper and faster than building new transmission."
"grid-forming" inverter is just software and parameters, your el-cheapo home solar inverter can do it too. It currently is prevented from doing so by ... grid operator regulations which ask it to disconnect at the first issue.
Let's talk about how you think inverters do frequency support without storage, which was the central point of my post.
They could easily have some spare/unused solar capacity (say 10%) and use it when frequency drops.
it also needs silicone carbide, which is the substance behind transformerless, inverter based
grid power switching
https://www.powerelectronicsnews.com/silicon-carbide-sic-ena...
https://www.powerelectronicsnews.com/silicon-carbide-sic-ena...
My state, Wisconsin, has had a long political and legal battle over the construction of high voltage lines from the Madison area to Dubuque, Iowa. Opposition ranges from aesthetics to wildlife conservation to it just being a waste of money.
One line of arguments I found intriguing is that the lines should be buried instead of on towers, for a multitude of reasons. The company building it would extract profit and then long term maintenance would fall on the state. If the lines were buried, there'd be less maintenance caused by weather events, less transmission losses, and overall more efficient and resilient operation.
Obviously burying such lines has much higher up front costs and the companies looking to profit don't want to pay it.
One line of arguments I found intriguing is that the lines should be buried instead of on towers, for a multitude of reasons. The company building it would extract profit and then long term maintenance would fall on the state. If the lines were buried, there'd be less maintenance caused by weather events, less transmission losses, and overall more efficient and resilient operation.
Obviously burying such lines has much higher up front costs and the companies looking to profit don't want to pay it.
> If the lines were buried, there'd be less maintenance caused by weather events, less transmission losses, and overall more efficient and resilient operation.
It's a tradeoff. When there is an issue with underground lines, it's much more expensive to locate and diagnose the fault and repair it; in both dollars and time.
In that area of the country, the ground freezes in winter, and digging becomes very difficult, which would make repairs that much more delayed and expensive.
Also, depending on requirements, it may be possible to augment capacity ny adding a second transmission line to the existing towers at a later time; that would be much less expensive than setting up the first line; but for undergrounding, such a project would most likely be as expensive as the first time, if not more. Similar with replacing the line at the end of its service life (although if the line and the towers have a similar service life, replacing them both brings costs back up similar to the initial project)
It's a tradeoff. When there is an issue with underground lines, it's much more expensive to locate and diagnose the fault and repair it; in both dollars and time.
In that area of the country, the ground freezes in winter, and digging becomes very difficult, which would make repairs that much more delayed and expensive.
Also, depending on requirements, it may be possible to augment capacity ny adding a second transmission line to the existing towers at a later time; that would be much less expensive than setting up the first line; but for undergrounding, such a project would most likely be as expensive as the first time, if not more. Similar with replacing the line at the end of its service life (although if the line and the towers have a similar service life, replacing them both brings costs back up similar to the initial project)
It's also quite common for above-ground transmission lines to be upgraded: swap the fixed supports for carrying wheels, hook up the existing conductor to a bigger or more modern one, and pull it through! An older line can get a nice 30% upgrade at very little cost this way.
> In that area of the country, the ground freezes in winter, and digging becomes very difficult, which would make repairs that much more delayed and expensive.
Could underground lines be placed in tunnels large enough for repair crews to reach where they need to work by going through the tunnel?
Well, I'm sure they could for runs that aren't too long, so perhaps the question should be over what distance is it economically and technically feasible to run underground lines in tunnels human accessible maintenance tunnels?
Could underground lines be placed in tunnels large enough for repair crews to reach where they need to work by going through the tunnel?
Well, I'm sure they could for runs that aren't too long, so perhaps the question should be over what distance is it economically and technically feasible to run underground lines in tunnels human accessible maintenance tunnels?
There's no technical limit on distance. It's just a tunnel (or more likely a vault) after all.
Economics are very handwavey. It would be very expensive but it offers benefits. How much are those worth and who is footing the bill?
Economics are very handwavey. It would be very expensive but it offers benefits. How much are those worth and who is footing the bill?
> If the lines were buried, there'd be less maintenance caused by weather events, less transmission losses, and overall more efficient and resilient operation.
You may find this video by Practical Engineering to be interesting: “Repairing Underground Power Cables Is Nearly Impossible”
https://www.youtube.com/watch?v=z-wQnWUhX5Y
You may find this video by Practical Engineering to be interesting: “Repairing Underground Power Cables Is Nearly Impossible”
https://www.youtube.com/watch?v=z-wQnWUhX5Y
Here's the text version: https://practical.engineering/blog/2021/9/16/repairing-under...
Noteworthy: That power line is only 10 miles long. Madison to Dubuque would be about 10X longer.
Noteworthy: That power line is only 10 miles long. Madison to Dubuque would be about 10X longer.
That "impossible" line was paired with a new line that doesn't require pumped insulating oil due to better insulating materials. Then the old line was de-energized and repaired, and is kept as a spare.
This news cycle was pretty hilarious (and just as sad) to hunt through.
From what I deciphered, the actual suggested cause was "aeolian vibrations" [0], which is one of the three forms of wind-induced conductor vibrations according to this [1] IEEE article. Also known as "flutter" according to Wikipedia [2]. (I'm not in EE so can't confirm nor debunk.)
Connected to this, another seemingly made-up term that made the news cycle was "Ging-induced vibrations" (in Portuguese media). Now, I don't speak Portuguese, but all my efforts hunting down this mysterious Ging tremendously failed. However, when I plopped ging into translation models, I couldn't help but notice that "ginga" in Portuguese means "swing", as in cable swing. So I'm giving it pretty reasonable chances that "ging" (no capitalization) might be what "flutter" is in English, i.e. the industry slang for "aeolian vibrations" there. And then the rest was just a typical journo move, much in the way of "the hacker known as 4chan".
In any case, it would have been cool if anyone actually linked to where said company made their statement, so that people could independently verify what was actually being said. From what I read, they have since explicitly debunked that they were inventing any new niche atmospheric effects. It's incredibly disheartening that such basic bits of information can become this seriously distorted before going viral, even (especially?) in this day and age. Makes you wonder how trustworthy are the regular news, even biases nonwithstanding, that aren't so readily obvious to be bollocks.
[0] https://www.youtube.com/watch?v=j-VzxRfPHjU
[1] https://ieeexplore.ieee.org/document/4773888
[2] https://en.wikipedia.org/wiki/Stockbridge_damper#Wind-induce...
From what I deciphered, the actual suggested cause was "aeolian vibrations" [0], which is one of the three forms of wind-induced conductor vibrations according to this [1] IEEE article. Also known as "flutter" according to Wikipedia [2]. (I'm not in EE so can't confirm nor debunk.)
Connected to this, another seemingly made-up term that made the news cycle was "Ging-induced vibrations" (in Portuguese media). Now, I don't speak Portuguese, but all my efforts hunting down this mysterious Ging tremendously failed. However, when I plopped ging into translation models, I couldn't help but notice that "ginga" in Portuguese means "swing", as in cable swing. So I'm giving it pretty reasonable chances that "ging" (no capitalization) might be what "flutter" is in English, i.e. the industry slang for "aeolian vibrations" there. And then the rest was just a typical journo move, much in the way of "the hacker known as 4chan".
In any case, it would have been cool if anyone actually linked to where said company made their statement, so that people could independently verify what was actually being said. From what I read, they have since explicitly debunked that they were inventing any new niche atmospheric effects. It's incredibly disheartening that such basic bits of information can become this seriously distorted before going viral, even (especially?) in this day and age. Makes you wonder how trustworthy are the regular news, even biases nonwithstanding, that aren't so readily obvious to be bollocks.
[0] https://www.youtube.com/watch?v=j-VzxRfPHjU
[1] https://ieeexplore.ieee.org/document/4773888
[2] https://en.wikipedia.org/wiki/Stockbridge_damper#Wind-induce...
Ginga is a Brasilian Portuguese word. I spent all of the day of the blackout listening to the radio (as you might guess) and not once heard the terms "ging" or "ging-induced". Also, ginga would not be swing as in cable swing, it would be swing as in swing dance (rhythmic movement specifically to music). When possible explanations were put forward in the media, they were attributed, usually either to the portuguese representative of REN (the Chinese company supplying power structure to the country) or to an analogous representative of Spain (where the fault originated). It was always pretty clear that the fault was unknown, since this was stated plainly by the aforementioned representatives and the prime minister. I respect the language barrier, but it would be good to take it into account.
Thank you, that's insightful. Seems like the machine translators misled me pretty hard there.
I'm part of a listserve for power systems engineers (more from academia than from industry) and the consensus seems to be that a couple of trips in short succession caused wild swings in powerflows, resulting in a cascading failure - this is a pretty boring, if consequential, N-2 event, very similar to the 2005 Northeast Blackout in the US.
"Diagnosis and Mitigation of Observed Oscillations in
IBR-Dominant Power Systems - A PRACTICAL GUIDE" - https://www.esig.energy/wp-content/uploads/2024/10/esig-rpt-...
Why were all the answers provided by new contributors? Don't see that very often.
I think a lot of people here would agree that AI/LLMs got them off of stackexchange (not just stack overflow) and it's refreshing to not have to deal with the moderation's instant "did you google" / "duplicate question". These new contributors will learn and switch over to chat.com soon enough
Not necessarily "new to StackExchange", but at least to the physics site.
Was posted less than 24 hours ago...
That's not how Stack Exchange works, though. You don't have to register for a new account every time you leave an answer. The replies were all from new accounts, not established ones. I don't think it has anything to do with the amount of time since the question was asked.
Can this be mitigated by putting the cables under ground? Just curious, since it’s a huge debate here at times because of the massive cost of doing so.
Germany needs a connection from the coast into the south and most of it as of now will be build under ground.
Germany needs a connection from the coast into the south and most of it as of now will be build under ground.
This article explains some issues with underground high tension cables [0]:
> Laying a 380-kV high-voltage line underground poses a number of risks. The electrical behaviour of underground cables differs from that of overhead high-voltage lines. This results in a loss of transmission capacity. To compensate for this loss, additional devices (e.g. coils) have to be installed at various points along the route.
> The combination of cables and coils creates resonance similar to a radio where multiple jammers continuously change frequency. Cables and coils can cause disruption locally, jeopardising the stability of the entire grid. In addition, it is easier for Elia to identify faults and carry out maintenance on overhead lines.
[0] https://www.elia.be/en/infrastructure-and-projects/infrastru...
> Laying a 380-kV high-voltage line underground poses a number of risks. The electrical behaviour of underground cables differs from that of overhead high-voltage lines. This results in a loss of transmission capacity. To compensate for this loss, additional devices (e.g. coils) have to be installed at various points along the route.
> The combination of cables and coils creates resonance similar to a radio where multiple jammers continuously change frequency. Cables and coils can cause disruption locally, jeopardising the stability of the entire grid. In addition, it is easier for Elia to identify faults and carry out maintenance on overhead lines.
[0] https://www.elia.be/en/infrastructure-and-projects/infrastru...
I had always heard that underground is workable for local areas but the really high voltage long-distance lines are hard to insulate undergound (on pylon towers they are not insulated at all).
High-voltage DC is frequently used for undersea transmission. This is necessarily insulated.
https://en.wikipedia.org/wiki/High-voltage_direct_current
https://en.wikipedia.org/wiki/High-voltage_direct_current
High voltage DC is effective above ground, too. At high enough voltage, it's actually cost effective and has fewer electrical losses than the AC equivalent. China has been doing some cool investments on high voltage DC in the past 15 years or so. We're talking 750 kV and above IIRC.
HVDC is the grid's distant future if the future is mostly solar. Why bother inverting to AC if everything making the power is fundamentally changing over to DC?
Easy: because DC voltage conversion is way harder.
You can't really build a "grid" out of HVDC, because you can't easily convert between what the solar plants produce (a few hundred volts), what the local distribution grid needs (a few thousand volts), and what is needed to get that power across the country (tens of thousands of volts). On the other side you need to convert back down to a city-level distribution grid, down to a street-level distribution grid, and in your home down to whatever your equipment needs.
DC-DC conversion is significantly more expensive, more failure-prone and less efficient than AC-AC conversion. Why bother with a bunch of expensive active electronics when a simple transformer can do the job even better? Besides, who's going to pay to retool the entire country? Just because a solar panel produces DC and your computer needs DC doesn't mean it's viable to use DC for the entire chain.
HVDC is excellent for long-distance transmission lines, especially when power almost always flows in a single direction. Want to hook up a solar plant in the desert to an urban area 1000km away? Use HVDC! Replacing the entire grid grid with it? Probably not the best idea.
You can't really build a "grid" out of HVDC, because you can't easily convert between what the solar plants produce (a few hundred volts), what the local distribution grid needs (a few thousand volts), and what is needed to get that power across the country (tens of thousands of volts). On the other side you need to convert back down to a city-level distribution grid, down to a street-level distribution grid, and in your home down to whatever your equipment needs.
DC-DC conversion is significantly more expensive, more failure-prone and less efficient than AC-AC conversion. Why bother with a bunch of expensive active electronics when a simple transformer can do the job even better? Besides, who's going to pay to retool the entire country? Just because a solar panel produces DC and your computer needs DC doesn't mean it's viable to use DC for the entire chain.
HVDC is excellent for long-distance transmission lines, especially when power almost always flows in a single direction. Want to hook up a solar plant in the desert to an urban area 1000km away? Use HVDC! Replacing the entire grid grid with it? Probably not the best idea.
This. AC generation is also way easier to reliably engineer at high power than DC.
Remember, early generators from Edison’s company were DC. They caught fire _constantly_. Obviously technology has caught up since then but AC power generation and distribution is simpler engineering overall. Use HVDC where you need it and it is cost effective to do so.
Remember, early generators from Edison’s company were DC. They caught fire _constantly_. Obviously technology has caught up since then but AC power generation and distribution is simpler engineering overall. Use HVDC where you need it and it is cost effective to do so.
[deleted]
There are significant inductive losses with having AC under ground - dirt is conductive enough you end up with induced current (inductive losses) in it. Same with seawater.
It’s doable; but for longer distance runs when buried or under seawater, it’s usually more economic using DC which doesn’t have that issue.
It’s doable; but for longer distance runs when buried or under seawater, it’s usually more economic using DC which doesn’t have that issue.
>>Can this be mitigated by putting the cables under ground?
Yes, it can (apparently), since these are mostly indirect effects of atmospheric vibrations (aka 'wind'). The vibration itself isn't usually the root cause of a blackout — but it sets off a chain reaction that leads to one (line contact/short circuit; conductor breakage; overcurrent & load shedding; protection system malfunction or overreaction, etc.)
Yes, it can (apparently), since these are mostly indirect effects of atmospheric vibrations (aka 'wind'). The vibration itself isn't usually the root cause of a blackout — but it sets off a chain reaction that leads to one (line contact/short circuit; conductor breakage; overcurrent & load shedding; protection system malfunction or overreaction, etc.)
You may find this video by Practical Engineering to be interesting: “Repairing Underground Power Cables Is Nearly Impossible”
https://www.youtube.com/watch?v=z-wQnWUhX5Y
https://www.youtube.com/watch?v=z-wQnWUhX5Y
It's vastly more expensive to put cables underground, and high voltage cables underground is in the realm of Bad Ideas because you're putting a high voltage physically near the electrical ground (the earth's crust), which adds cost, reduces reliability, and poses a serious danger to all living things near the line.
Sure, there may be exceptions that might make it worth while. However, if long distance high voltage underground wires was practical and cheap, you would see deployed much more often.
Sure, there may be exceptions that might make it worth while. However, if long distance high voltage underground wires was practical and cheap, you would see deployed much more often.
> poses a serious danger to all living things near the line
That is always the case for the various failure modes of any high voltage line (and all the related equipment).
That said, you have it exactly backwards. Above ground lines are much easier to inadvertently come into contact with. Once faulted the breaker trips within a matter of milliseconds. It's the initial contact that's deadly.
That is always the case for the various failure modes of any high voltage line (and all the related equipment).
That said, you have it exactly backwards. Above ground lines are much easier to inadvertently come into contact with. Once faulted the breaker trips within a matter of milliseconds. It's the initial contact that's deadly.
I think they might have been referring to conductor gallop, power line sag, and subsequent fault. I read synchronisation failure as downed cable. With extreme temperature variations come extreme winds. Not sure if this was the case.
[deleted]
Accepted answer posits that this may be due to a mistranslation from Spanish, or someone's misunderstanding of an explanation, or both.
In other words, the phenomenon is another "vegetative electron microscopy".
In other words, the phenomenon is another "vegetative electron microscopy".
That answer has 4 upvotes. A much more electrically literate answer above it, with 35 upvotes, explains in detail that it is a real thing.
The accepted answer is not electrically illiterate in any way.
The upvoted answer, while it may be correct, doesn't argue for the existence of the phenomenon called "induced atmospheric vibration".
It may be that it's supposed to refer to corona discharge, which does make a sound ("atmospheric vibration"). But that sound is not the root cause of anything; it is just a side effect of no consequence.
It is a plausible hypothesis that "induced atmospheric vibration" it's just someone's misunderstanding (possibly of an explanation similar to what's in that upvoted answer), with some misstranslation being a contributing factor.
The two answers simply don't contradict each other.
The upvoted answer, while it may be correct, doesn't argue for the existence of the phenomenon called "induced atmospheric vibration".
It may be that it's supposed to refer to corona discharge, which does make a sound ("atmospheric vibration"). But that sound is not the root cause of anything; it is just a side effect of no consequence.
It is a plausible hypothesis that "induced atmospheric vibration" it's just someone's misunderstanding (possibly of an explanation similar to what's in that upvoted answer), with some misstranslation being a contributing factor.
The two answers simply don't contradict each other.
government official had to make press conference just to tell people to stop spreading that nonsense you promote as "electrically literate" so that is that.
whole stack overflow question is bunch of nonsense, so why do we even argue about it?
whole stack overflow question is bunch of nonsense, so why do we even argue about it?
Spanish grid operator (Red) preliminary Engineering Report seems to be blaming renewable generation (solar) for the initial drop followed by second drop 1.5 seconds later.
Where can one find the report? Couldn't find anything on their website or elsewhere. I was only able to find the following media briefing via Reuters [0]:
> REE's System Operations Chief Eduardo Prieto told a news briefing the electricity system was hit by a dramatic power generation loss in southwestern Spain, that caused instability in the system that led to its disconnection from the French grid. He said it was quite possible that the affected generation was solar, but it was too early to say for sure.
This doesn't quite read like them blaming solar either. If anything, they're painting it as one of the victims of the failure.
[0] https://www.reuters.com/world/europe/spanish-grid-operators-...
> REE's System Operations Chief Eduardo Prieto told a news briefing the electricity system was hit by a dramatic power generation loss in southwestern Spain, that caused instability in the system that led to its disconnection from the French grid. He said it was quite possible that the affected generation was solar, but it was too early to say for sure.
This doesn't quite read like them blaming solar either. If anything, they're painting it as one of the victims of the failure.
[0] https://www.reuters.com/world/europe/spanish-grid-operators-...
I'm going to speculate it was the following:
1. System was running with low inertia due to a high amount of renewable generation (mainly solar).
2. Something caused a large amount of generation to trip. Lack of inertia in the system can't arrest the frequency drop.
3. Rate of change of frequency (ROCOF) protection kicks in and trips renewable generators; interconnectors to France also trip as they are suddenly overloaded. Islanding and blackouts ensue.
1. System was running with low inertia due to a high amount of renewable generation (mainly solar).
2. Something caused a large amount of generation to trip. Lack of inertia in the system can't arrest the frequency drop.
3. Rate of change of frequency (ROCOF) protection kicks in and trips renewable generators; interconnectors to France also trip as they are suddenly overloaded. Islanding and blackouts ensue.
Interestingly, the recent deadly floods were also blamed on a rare atmospheric event. Sadly, it seems official information during such events is just as rare.
No power is unusual, but happens, but no mobile phones, no internet, no emergency broadcasts, SMS or otherwise, just complete silence for hours... and then you hear it might be multi-country wide. Pretty scary. You assume the worst, right?
What was also scary to see was how little cash people have. The cash machines went down, queues formed, banks closed, POS terminals failed, and suddenly the smart-world we are building was looking very dumb.
Imagine not being able to buy basic essentials like medicines, food and water. Hopefully more people will reject cards / digital money as a result of this crisis.
But I also wonder what contribution the massive new solar farms and wind farms had on this crisis. That supply must be quite variable, and subject to rare atmospheric events such as clouds...
Sorry to rant, it was a pretty upsetting experience.
No power is unusual, but happens, but no mobile phones, no internet, no emergency broadcasts, SMS or otherwise, just complete silence for hours... and then you hear it might be multi-country wide. Pretty scary. You assume the worst, right?
What was also scary to see was how little cash people have. The cash machines went down, queues formed, banks closed, POS terminals failed, and suddenly the smart-world we are building was looking very dumb.
Imagine not being able to buy basic essentials like medicines, food and water. Hopefully more people will reject cards / digital money as a result of this crisis.
But I also wonder what contribution the massive new solar farms and wind farms had on this crisis. That supply must be quite variable, and subject to rare atmospheric events such as clouds...
Sorry to rant, it was a pretty upsetting experience.
I did indeed fear the worst, and did a WWIII top-up shop to add some extra essentials to my usual disaster prep.
Luckily not needed, but an interesting experience.
We were pretty lucky here. The local big box was running on emergency power from its solar roof, and ATMs and card payments were still working - much to my surprise. Smaller stores were taking cash and the larger smaller stores were limiting access and sending customers around individually with staff with torches.
A lot of people were obviously prep-shopping, but it was controlled and pretty relaxed.
I even had 5G of a sort - intermittent and slow, but I could just about keep up with news updates.
In the end it was a 12 hour blackout, which was more of a major inconvenience than the catastrophe that would have happened if it had taken days.
Luckily not needed, but an interesting experience.
We were pretty lucky here. The local big box was running on emergency power from its solar roof, and ATMs and card payments were still working - much to my surprise. Smaller stores were taking cash and the larger smaller stores were limiting access and sending customers around individually with staff with torches.
A lot of people were obviously prep-shopping, but it was controlled and pretty relaxed.
I even had 5G of a sort - intermittent and slow, but I could just about keep up with news updates.
In the end it was a 12 hour blackout, which was more of a major inconvenience than the catastrophe that would have happened if it had taken days.
I was also doing my top-up shop, and was surprised how orderly the shelves were being stripped of water and essentials. No panic, maybe some nervous tension, but otherwise could have been a long weekend big shop for most people.
I realised my regular disaster prep was lacking in a few areas. I especially want a decent portable radio, and a set of walkie-talkies, but everything looks pretty gimmicky from a quick search. Any reccomendations? I got access to a radio after 3 hours, not that there was anything official at that point, but it was enough to switch down a gear.
I realised my regular disaster prep was lacking in a few areas. I especially want a decent portable radio, and a set of walkie-talkies, but everything looks pretty gimmicky from a quick search. Any reccomendations? I got access to a radio after 3 hours, not that there was anything official at that point, but it was enough to switch down a gear.
What I've been reading from multiple sources is that the electrical grid was in a brittle state because of the large percentage of solar and wind energy, as these sources are intermittent and unable to maintain the required AC frequency on their own. Apparently, it would be possible to make a renewable-heavy grid more resilient to these kinds of events, but Spain had not invested enough on the necessary infrastructure.
At the moment of the blackout, ~70% of the energy was being produced by solar and wind when sudden events caused a large loss of power and that brittle grid was knocked down as a whole.
There is a huge political row at the moment because the government has encouraged investment in solar and wind for a long time, so they are unlikely to admit that they might have contributed to the problem. Furthermore, they have closed down and demolished the remaining coal plants, and they plan to close down all the nuclear power stations.
At the moment of the blackout, ~70% of the energy was being produced by solar and wind when sudden events caused a large loss of power and that brittle grid was knocked down as a whole.
There is a huge political row at the moment because the government has encouraged investment in solar and wind for a long time, so they are unlikely to admit that they might have contributed to the problem. Furthermore, they have closed down and demolished the remaining coal plants, and they plan to close down all the nuclear power stations.
Wow, 70% is pretty impressive. Although everywhere I go I see huge areas of farmland being converted into privately owned giant solar farms. At least the turbines are mostly non-productive land.
Of course it would be much more stable if the generation was close to consumption.
But the energy companies have fought before to limit homeowner solar installations to maintain profits. The EU broke that corruption, but the local town hall is still saying I need a permission.
The electric companies want me to conect to the grid, and pay for that privalage, but wont pay me for excess generation. Do these smart-meters even allow 'islanding' in such a crisis?
Anyway, it seems like this incident just exposed a very big single-point-of-failure, technically, and an even bigger general failure of modern politics.
Of course it would be much more stable if the generation was close to consumption.
But the energy companies have fought before to limit homeowner solar installations to maintain profits. The EU broke that corruption, but the local town hall is still saying I need a permission.
The electric companies want me to conect to the grid, and pay for that privalage, but wont pay me for excess generation. Do these smart-meters even allow 'islanding' in such a crisis?
Anyway, it seems like this incident just exposed a very big single-point-of-failure, technically, and an even bigger general failure of modern politics.
My understanding is that coal/nuclear/gas plants provide a certain amount of stability thanks to the rotational inertia in the turbines. It seems like a relatively inexpensive way to retain that capacity would be to keep the old turbines to function essentially as flywheels, to stabilize the grid, after the plants powering them are shut down.
April 1 already?
Excellent accessible explanation.
All of these seem to be more or less conjecture on a seemingly lost-in-translation phrase though?
[deleted]
It's a fake term, used by the government to hide the real cause - deteriorating magnetic field, that will flip in 15-25 years, but we will start seeing a lot of issues similar to that event more often.
[citation needed]
They had me at this