"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
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.
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.
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.
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)
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.
belter•7h ago