"Real electrical systems have to deal with issues of reactance and other exciting math-heavy constructs designed to drive you into some other field of study."
Summarizing a couple of year of very annoying electrical studies: Yes
You can't believe how much
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...
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.
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.
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.
Funny enough, AC+DC (hybrid transmission) on the same lines is active research.
https://electrical-engineering-portal.com/download-center/bo...
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.
I'm short, it's this way for a reason. The complexity is nessessary.
For non-physicists: https://electronics.stackexchange.com/questions/128986/why-u...
That is not possible with DC.
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...
Germany needs a connection from the coast into the south and most of it as of now will be build under ground.
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.
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.
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.
> 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...
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.)
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.
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.
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.
You may find this video by Practical Engineering to be interesting: “Repairing Underground Power Cables Is Nearly Impossible”
Noteworthy: That power line is only 10 miles long. Madison to Dubuque would be about 10X longer.
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)
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?
Economics are very handwavey. It would be very expensive but it offers benefits. How much are those worth and who is footing the bill?
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.
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.
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).
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.
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.
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.
https://www.powerelectronicsnews.com/silicon-carbide-sic-ena...
> 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.
In other words, the phenomenon is another "vegetative electron microscopy".
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.
whole stack overflow question is bunch of nonsense, so why do we even argue about it?
> 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-...
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.
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.
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 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.
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.
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.
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...
belter•7mo ago