Guest post by Rud Istvan
Charles asked whether I would critique this new nonsense. Sure, why not.
The highlighted ‘sciency’ article purports to create an ‘open source’ grid data resource using 17 ‘synchronous grid’ European regions to design and test how “that will help develop new power systems capable of meeting changing demands, such as the move towards renewable energy sources.” NOPE, this won’t help at all.
The body of this silly paper found observationally lower grid frequency variations in larger ‘isolated’ European subgrids! Of course larger grids have less frequency variation— something trivially true and known for many decades. The reasons are intuitive and simple. Larger grids by definition have more generation feeding the grid, so more grid inertia, and at the same time less ‘instantaneous load variation’ by simple virtue of the statistical law of large numbers.
Grid inertia is just the frequency stabilization that comes from the kinetic energy of large rotating generator masses. As grid load ‘instantly’ increases, the frequency sags and the generator wants to slow down. But by slowing, it also ‘instantly’ injects some of its rotational kinetic energy until the driving source (steam, or natural gas in CCGT) can be turned up a bit to compensate.
CCGT is particularly good at this. It runs about 61% efficient at full load, 60% efficient at 80% load, and still 59% efficient at just 40% load. The gas turbine power reaction time is literally about a second no different than a jet engine.
None of this ‘open source data resource’ helps ‘the move to renewables’. Basic grid electrical engineering (EE) is simple and inescapable concerning renewables— they are uneconomic (investment always falls when subsidies dry up), intermittent (requiring underutilized backup generation), and provide no grid inertia (which is automatic with big fossil fuel fired generators). ALL BAD.
Irsching Bavaria‘s about 10 year old CCGT units 4 (375MW) and 5 (860MW) illustrate the problems that intermittent renewables lacking grid inertia create for any grid. The owner wants to take them out of service because very unprofitable when run mainly as wind backup rather than grid load. The German government refuses to make up the difference, yet also refuses to let them shut down.
In the bigger German renewable picture, northern Germany exports surplus wind power to Norway as essentially a giveaway. That lets Norway throttle back its hydro. Then, when Germany needs power because wind is insufficient, Norway spools up its hydropower and sells it to Germany at exorbitant rates. To make matters worse, the German NIMBY crowd won’t let the utilities install more much needed North-South German transmission interconnect ‘eyesores’—despite wind turbines that are bigger and uglier.
A small amount of renewables in a large stable grid presents no problems–and no need for this new study. The backup capacity (spinning reserve) and grid inertia are already there. But as renewable penetration grows as a proportion of any stable ‘synchronous’ grid, these issues grow and compound. Depending on grid details (like how much flexible hydro), renewable penetration above about 8-10% ALWAYS creates extra costs and stability problems. Alternating current grid engineering has been known now for well over 100 years, and nothing ‘new’ can change the established maths, physics, and electrical engineering (EE).
There is also some ‘basic EE stuff’ this new ‘open source data resource’ ignored.
First, their ‘new’ grid frequency data is almost always available from the utilities (grid operators), since required to manage the grid. It is captured both at the generating plants and at the transmission to distribution substations. Perhaps they should have just asked for the utility data rather than gathering their own.
Second, their super duper ‘proprietary’ grid frequency detectors for capturing their new open source data can be purchased almost anywhere. Such detectors are a common electrician’s tool. A very high-end multipurpose ‘pocket’ unit is the Extech PQ3450 power quality analyzer, pictured.
Third, their finding that grid frequency sags when demand exceeds supply and rises when supply exceeds demand has been known since Tesla first envisioned AC generation by using complex numbers (a+bi). The US is designed to be a stable 60 Hertz, EU 50 Hertz. Because electric clocks depend on grid frequency, ‘stable’ is about plus/minus 0.2Hz in the US.
Just for fun (because the above is all well trod ground at WUWT and Climate Etc), we also provide a simple math/science fun challenge to those at WUWT unfamiliar with AC electrical stuff. (Thanks to a physics book full of hundreds of such challenges, sadly in Chicago rather than Fort Lauderdale, which I half reconstructed from memory and half from Google ‘facts’). It is about right.
Imagine a high voltage AC transmission line between Chicago and New York. (Hint: the distance does not matter much for this challenge, voltage does some, but is always ‘high’.) The challenge: how far does a single electron charge travel during its journey along this transmission line? Choices:
- Kilometers
- Meters
- Centimeters
The speed of light (aka electromagnetic radiation) is about 299792458 meters/second in a vacuum. But ‘electromagnetic force (emf) wave guide’ wires are definitely not vacuum; their metals have electrical resistance (technically grid AC impedance, a combination of circuit resistance and reactance). Although electrons pushed along by emf have essentially no mass, they still slow down lots in metals.
Skipping a bit of complex math explaining very simple physics, the reason you buy ‘fat’ DC audio cables with gold terminals is simple: DC current flows across the entire conductor cross section fairly uniformly. A fatter cable has uniformly less cross sectional resistance (DC speaker output is analog), and gold terminals lower connection resistance further since gold doesn’t corrode. The result is truer high frequency pitch amplitudes. As a side factoid, this same physics is why ‘fat’ high voltage DC transmission lines are preferred for long grid distances, like the Germany to Norway undersea interconnects mentioned above.
The ‘fat’ AC cable answer is different. AC current has a conductor skin effect. Unlike DC current, AC current travels mainly in an annular ‘skin’ ring whose thickness depends on frequency (higherèthinner) thanks to interesting AC consequences of Maxwell’s equations as explained by Feynman’s ‘Lectures on Physics’ V. 2 chapter 32, ’skin effect’. In a ‘pure’ copper conductor, that annular skin travel (the center of the conductor essentially carries no AC current) is only about 3.2 meters per second. The much more common (cheaper, lighter) aluminum HV transmission conductor is only about 61% of copper. So in aluminum high voltage transmission lines electrons travel at best about (3.2m/s*0.61) ~1.95 m/s ignoring skin oxidation.
AC is a sine wave varying from 0 to plus emf to 0 to minus emf to 0 at x times a second, (US 60Hz, EU 50Hz). One cycle is from zero voltage to max emf to zero to opposite polarity max emf back to zero. The emf back and forth is a nominal US 120 peaks/second, 60 times in each direction. (Side note: unlike most DC circuits, AC emf is related to, but not the same as, voltage.) For simplicity imagine this AC challenge as simply digital rather than sine wave (all on or all off emf rather than a varying emf sine wave), thereby removing any need for the correct calculus challenge formulation. Then the most distance a virtually massless electron could travel in its aluminum high voltage skin is about (1.95/60) 3.2 cm, back and forth and back and forth. The actual (sine wave emf calculus) US answer is less than one centimeter back and forth, and EU less than 2. That is because there isn’t a lot of emf except near the peak and trough of the sine wave, slowing down intermediate time things further. Either answer (over simplified or correct) results in not very much electron travel distance (c).
Returning to the main topic of this guest post, despite this new European ‘ grid research’:
Anywhere, anytime, renewable subsidies get reduced, so does investment in them. They are provably uneconomic, stand alone.
Renewables are intermittent; yet do not cover the backup costs of intermittency.
Renewables provide no grid inertia; yet do not cover the costs of providing frequency stability using massive synchronous condensers.
More research and new ‘open source’ data resources concerning fundamentally bad propositions does not improve them. NOPE!
Didn’t you mean a DC line?
In an AC line the electrons go precisely nowhere – they *try* to joggle back/forth but actual progress in either direction is zilch nil nada.
Bit like Climate Science
It is the *effect* of them *trying* to move that moves at light speed, or about two-thirds of light speed in a typical transmission line.
What we all *really* want to know is why vacuums have properties.
If there is a current flow – then the electrons must move. In AC, the electron POTENTIAL will increase up and down, but there will be a net migration of electrons. Otherwise – no current. Do not confuse potential (voltage) with current! The results of getting it wrong are shocking…:)
Math says: the average voltage on an ac line is zero. The average current in an ac line is zero. 🙂 (pedantic man strikes again)
If you want to get pendatic.
Power is current times voltage.
In AC average current is zero. Average power is zero. Yet average power is not zero.
This is because thanks to inductance not being zero, current and voltage are out of phase.
No. The power is the integral of the voltage at each instant times the current at each instant. For a resistive load, the result is always positive.
NO! Energy is the integral of the product of voltage and current at each instant in time. POWER is the product of voltage and current at each instant in time, no integral involved.
Energy (wattsec, joules) is the integral of power (watts).
Yep. I forgot to mention dividing by the period of the integration.
No at one point in time the are moving forward the next point in time they move back in the US that happen sixty time a second so the movement is zero. It not that the electrinos are not doing work they are.
Vacuum is not a ‘volume’ that contains nothing. Maxwell defined vacuum as space where everything is removed that can be removed. There are no two identical vacuums, they are different because of the different level of energy. Beside fact that any vacuum on this planet is jam-packed with the bog standard electromagnetic waves and magnetic fields it’s also permeated by various ‘rays’ (em waves) as well as neutrinos and other more energetic particles. Particle physicists are telling us there are in there very short lived elementary particles and antiparticles continuously annihilating themselves and some of those entangled particles where one might be in the vacuum and another at ‘far end’ part of universe, not forgeting Higgs bosons. Mind boggling.
Exactly, no time line was stated so in an AC system with no DC present it has to be zero or average towards it with increasing time.
FYI – In a high voltage DC line typically operate in bipolar mode (two lines) with electrons flowing one way on one line and the opposite on the other. Should you lose a line HvDC can operate in a mono-polar mode using the ground for the return path. However the electrodes in the ground corrode pretty fast when this mode is used.
In California, the state with the least reliable electrical power system in the nation, between 2008 and 2017, the Golden State experienced far more individual outages with almost 4,297 individual outages in the ten-year period, more than 2.5 times as many as its closest rival, Texas. The state continues shuttering most of the in-state natural gas and nuclear power plants that have been providing continuous uninterruptible electricity, in favor of intermittent electricity from wind and solar while adding EV charging loads onto the grid. Power outages are now commonplace in California with more to follow for the Golden state.
Good article, thank you Rud.
I started writing about the abject failure of grid-connected wind and solar power generation in 2002.
Wind and solar power do NOT contribute significant economic electric power to the grid. Both fail due to intermittency and diffusivity – they vary too much and take up too much land.
These are proven facts, yet trillions of dollars have been wasted globally on this green energy fraud.
I posted the following , probably circa 2010, for our idiot politicians and the mainstream media:
“WIND POWER: IT DOESN’T JUST BLOW – IT SUCKS!”
“SOLAR POWER: STICK IT WHERE THE SUN DON’T SHINE!”
Apparently that is still too complicated for most media and politicians.
You have to remember our media were people who in collage could not do STEM or even bright enough to be teachers and they did not want to be plumbers(who make more money!) Add in most politicians are failed lawyers(lawyers at most all you need is a good memory) so if you wonder why we are in the fix we are in. When the LCD run something don’t expect good results!
Istvan neglects to mention that the mass of a large wind turbine blade has a LOT of inertia.
Doesn’t help grid stabilization. Wind turbine rotation is not synchronized to the grid. Their AC output is synthesized.
https://www.nrel.gov/docs/fy20osti/73856.pdf
See page 28, section 7.3.2
Yes, the big-ol’ blades have some inertia, but it isn’t nearly what you think it is. The above quote drawn from your reference says as much.
Kevin
The wind turbines are not locked into grid speed so provide no inertia. What they were proposing for wind turbines (and wanting to be paid for) was running the winmills underloaded so they could inject generation in if the frequency dropped. Sort of a synthetic droop.
A 3MW turbine’s blades are 47m in length and weight about 12,500 kilograms. There are three of them. That is a lot of spinning mass. Oh, and a wind farm might have several dozen or more turbines.
bethan456@gmail.com
But they don’t run at 50 / 60 Hz
bethan456 clearly does NOT understand what grid inertia actually is in terms of frequency and phase matching.
I think he/she imagines the turbine is just spun up by whatever the wind is doing and then directly connected to the grid. A simpleton. Libs hate the complex engineering and mathematics involved. That’s why most go to fuzzy studies and the ever popular Liberal Arts degrees in basket weaving and finger painting.
Wind turbines use the grid to provide excitation (field reference) for their generator stator windings, to allow a stable 60Hz output under changing wind conditions. What is being described is adjustable phase excitation, which certainly is possible but requires a stable local reference. The challenge comes when many such local references exist across the grid, and can easily react to each other potentially causing oscillations. The current system relying on mechanical inertia can exhibit such resonant behavior as well, but it’s a far simpler problem dealing with fewer, more massive generators (slow time constants and high impulse power), than with many comparatively small generators whose impulse power is more limited (mechanical stress on the blades must be controlled). It seems to me that adopting such a system in wind farms would make for a grid more susceptible to tuning issues and shorten the already limited life of the wind turbines.
In the summary they say: “Replacing conventional generators with inverter-based resources, including wind, solar, and certain types of energy storage, has two counterbalancing effects. First, these resources decrease the amount of inertia available. But second, these resources can reduce the amount of inertia actually needed —and thus address the first effect.”
As they say, wind reduces the amount of inertia available, but they can (i.e. might be able to) reduce the need for inertia.
They also say “The development of new “grid-forming” inverters enable inverter-based resources to take a more active role in maintaining reliability and could be an integral technology for a purely inverter-based grid.” saying that this technology could be of help when it becomes available.
From 7.3.2
Modern wind turbines do not use synchronous generators and therefore do not provide inertia in the traditional sense (defined as inherently resisting changes in frequency). However, wind turbines do have kinetic energy in the rotating mass of the blades, shaft, and generator that can be extracted to rapidly inject real power into the grid.
Provision of this service requires active sensing of grid frequency, so that when a decrease in frequency is sensed, the generator can be programmed to increase output to beyond what can be supported by steady-state wind speeds (Ela et al. 2014).
So again , they are saying that Wind does not provide rotation inertia directly into the grid, but with the development frequency sensing technology, its non-synchronous inertia can be used to “inject real power into the grid”.
They also say “The plant then increases generation by about 70 kW in less than 0.5 seconds (in addition to the initial 0.4-second response time), or by about 10% of rated capacity per second. After this initial increase, the wind turbine will exhaust much of its stored kinetic energy, and its output will reduce. As with conventional inertia, this action can slow the frequency decay long enough for other mechanisms, including slower responding mechanical PFR (primary frequency response), to arrest and help restore frequency. ”
In other words, this effect will only last for a very short time then you’ll need a “PFR” (i.e. a Hydro, Nuclear or Fossil Fueled powerplant) to pick up the slack as wind will be of no use in handling the additional load since wind can not be throttled up to handle the extra load.
I wonder how much extra stress, this rapid slowing of the turbine blades is going to put on the hub/generator?
This is not a type of stress they were designed to handle.
And RicDre – is it even possible to build and operate a large scale grid with NO synchronous generation?
“is it even possible to build and operate a large scale grid with NO synchronous generation?”
Probably not. And trying to cold start a crashed grid without synchronous generation seems eve more improbable.
A few considerations:
– wind just won’t blow at a constant speed thereby allowing for a stable inertia.
– your inertial mass can’t be that great, otherwise your wind generator wouldn’t start moving when you needed it
Guess what – you can very precisely measure, tune and maintain that rotation inertia (in for instance a large flywheel) from a gas or steam turbine, which will also allow you to have a much, MUCH larger rotational mass than you could manage from any wind turbine.
And don’t even propose a single flywheel powered by an entire windmill park because the energy conversions alone would destroy any output from it.
You’d have to succeed in outlawing all laws of nature interfering with effiicent wind turbines for them to be viable. Keep us posted how that’s going.
The California Legislature will simply repeal all those laws.
Well, not really. Yes the turbine have a lot of inertia but their generating components are not running at synchronous speed. Those large rotor blades do not have pitch controls. They are simply too heavy to use with a motorized hub that would adjust the blade pitch to produce a fixed generation frequency.
They produce a varying AC frequency output that is rectified and applied to solid state high power inverters that produces the 60/50 Hz output to the grid. Some work has been done to add control logic to the inverters to simulate rotating generator inertia. Though useful for small load bumps, that design enhancement has not and can not provided the same grid stability as large rotating mass generators.
“Those large rotor blades do not have pitch controls.” Some turbines do not, some do. Are you saying the really large (40 ft) blades are all stationary on the hubs? How do they keep from self destruction in excessive winds? Just yaw control?
The large turbines do modulate wind power input with pitch control to both feather the blades when the wind gets to strong and to maintain an optimum frequency for the generator, which is often much higher than 50/60 Hz. This is because you want to minimize the mass at the top of a 100′ stalk and a 2 MW 600 Hz generator is much smaller, lighter and cheaper than a 2 MW 60 Hz generator. Grid attachments are now almost exclusively done with electronic controls as it’s more robust and safer for both the grid and the generator, especially when you have a source of generation that can come and go without warning.
There is inertia but it must maintain frequency for the inertia to be usable. You cannot allow the frequency to change – this is why directly connected wind turbine blades are all in lock step in a windfarm.
However turbines used to produce DC but with grid AC being generated by electronics e,g, Enercon https://www.enercon.de/en/home/ will provide grid connection until dc voltage is too small for the system to work.
These enercon WECs will also help to reatore a black grid.
Who cares?
Why wouldn’t you just use nuclear?
@bethan456: When the wind isn’t blowing a wind turbine has no inertia, and wind output can be at or near zero for hours and even days at a time. While the inertia in wind turbines can help provide short term voltage stability some of the time, essentially 100 percent backup of wind and solar generation capacity is required. Also, dispatchable generation must be available to make up for the very large upward and downward ramps in wind and solar output that can occur over short periods. Renewables advocates seldom consider all the costs rhat renewables impose on the transmission grid and other generators in their economics.
BPA wind turbines are in a two week calm.
https://transmission.bpa.gov/business/operations/wind/baltwg.aspx
Wind turbine blades are fiberglass/plastic with hollow foam filled or even wood cores. Gas turbines use superalloys heavier than steel:
“A nickel-based alloy suitable for use in making gas turbine components, such as rotating blades is provided. The alloy comprises the following elements in weight percent: Chromium 14.75 to 16.0, Cobalt 8.0 to 8.5, Aluminum 3.4 to 4.0, Titanium 3.4 to 4.3, Aluminum plus Titanium 7.7 to 8.3, Tantalum 1.75 to 2.7, Tungsten 2.0 to 4.0, Columbium up to .5, Molybdenum up to 2.0, Carbon .05 to .12 and the balance Nickel. The alloy of the current invention may also comprise impurities and incidental elements generally associated with nickel-based alloys, such as Zirconium up to .06 and Boron up to .015 percent by weight.” (Westinghouse patent)
Rud didn’t “neglect to mention” the inertia of windmill blades. His point was that useful inertia was a property only of fossil fuelled turbines in an electrical grid. Do your homework to comment on technical stuff especially at WUWT.
Mass of a typical wind turbine blade – 12 tons. Mass of the Hoover Dam rotors – 517 tons.
Now, it makes little difference whether your Tesla is run over by a dump truck or a freight train – but it makes quite a bit of difference in how much kinetic energy is involved.
It isn’t the mass but the rotating inertia that matters. A high speed steam turbine often has a lot more inertia than a hydro turbine weighing a lot more because of the rotational speed component which is a squared factor.
12 tons each, three per turbine, and how many turbines in the wind farm? Oh….don’t forget that the diameter of the turbine is a factor in calculating the stored energy of the rotating mass. (one kilogram on the end of a 50 meter blade has a lot more velocity than one kilogram on the edge of a Hoover dam rotor)
And all at slightly different speeds..
You STILL haven’t figured out the grid inertia thing,
Have you
Hint.. STOP DOUBLING DOWN on you STUPID….. its too embarrassing to watch. 🙂
Wind farms can provide “synthetic inertia.” As discussed in https://spectrum.ieee.org/energywise/energy/renewables/can-synthetic-inertia-stabilize-power-grids:
It really is amazing how tightly a progressive will cling to a disproven idea.
Rotation per minute of a wind turbine is 15 to 20 rpm? versus 180rpm for the Hoover dam water turbines? Given that a nominal figure of mass for a wind turbine blade is 5 tonnes times 3 gives 15 tonnes of rotating mass. Hoover dam turbines weigh 400 tons or 360 tonnes.
My back of the envelope calculations suggest the kg at the end of a wind turbine has 4 times the energy offset by there being 24 times the mass in the hoover dam turbine.
I neglected many contributing factors including the respective masses of the attached generators. I suggest that the total rotating mass would be a better comparison but i cannot be bothered.
has a lot more velocity
No, when there is no wind velocity is zero.
bethan456,
Thank you for demonstrating your basic ignorance of how wind turbine outputs are actually connected to the grid. Give some thought to how dozens to hundreds of independently spinning turbines in a wind farm MUST synchronize their output to one frequency and 3 phases to match the grid frequency-phases before injection.
So, you can educate yourself, and relieve yourself of that ignorance. Or…
you can remain an intentionally and blissfully clueless moron like most libtards.
Wind turbine could only provide grid stabilization if they were connected directly to the grid.
They aren’t
They , in fact RELY on the stable grid frequency to be able to synchronise to that frequency.
The “black box controllers” don’t work the other way around.
If the wind stops blowing they have no inertia.
“Using power electronics, inverter-based resources including wind, solar, and storage can quickly detect frequency deviations and respond to system imbalances. Tapping into electronic-based resources for this “fast frequency response” can enable response rates many times faster than traditional mechanical response from conventional generators, thereby reducing the need for inertia. ”
..
Reference: https://www.nrel.gov/docs/fy20osti/73856.pdf
And of course, extra losses. As you need to rectify the AC voltage to DC, then re-form the AC waveform – both of which are quite lossy (on the order of 3-6%). So yeah, we can toss away 10% of the energy to make a more frequency-stable grid – but we could also just go with really big inertia (mass) at the generator in the first place and be done with it.
This only works if you have a reserve of stored energy to tap, for example, the spinning mass stored in a generator. Solar cells and windmills do not have this which is the problem being discussed. A massive amount of batteries are required to supplement unreliable sources of energy, which are very uneconomical, inefficient, have a limited lifetime and in the future will become a massive toxic waste problem among their other problems.
Here’s a question for you. If your power company offered you a choice between unsubsidized ‘green’ energy at its true cost of about $0.50 per KWH or unpenalized fossil fuel energy at it’s true cost of less than $0.10 per KWH, which would you choose? And as far as I’m concerned, the indisputable fact that the science justifying green is so corrupt it de-legitimizes all science shouldn’t even matter to the choice.
Don’t believe claims that ‘green’ energy is free or that CO2 emissions are an existential threat. These claims come from the same blowhards who claim that Hunter Biden’s influence pedaling was Russian disinformation, that there was no cheating in the recent election, that open borders are good for America, that Swalwel’s dalliances with a Chinese honey pot were not a national security threat, that neither the media or big data has a far left Socialist bias, that the hate they proselytize originated from Trump, that Socialism is a viable system and so much other BS that to know the truth means to accept the opposite of what they claim.
“…and windmills do not have this ” Again, 12 tons per blade, three blades per turbine multiplied by the number of turbines in the wind farm.
Wrong frequency and not useful. Consider how useful the spinning mass of a generator would be if the steam or water stopped flowing to replenish the lost energy.
co2isnotevil December 13, 2020 at 10:08 am
Wrong frequency and not useful.
—————
exactly. Spinning turbines slow down too/
With the turbines from fossil fuel plants or hydro plants, the slow down in the turbines can be compensated for by increasing the amount of steam or water being thrown at the turbines. This is one of the reasons why such turbines are not normally run at 100%.
How many minutes does it take to change the pitch of a wind turbines blade so that it can compensate for this extra drag.
Beyond that, a rapid slowing of a wind turbine blade places huge amount of strain on the hub because of the length of each turbine blade. This isn’t the case with much more compact steam or hydro turbines.
bethan et al.
You remind me of the old joke, “Don’t confuse me with facts! My mind is made up.” It is obvious to me that your technical qualifications pale in comparison to your critic’s qualifications. They have provided you with good reasons why your beliefs are wrong, and the best you can come up with is to repeat your mantra, “…, 12 tons per blade, three blades per turbine multiplied by the number of turbines in the wind farm.” There is little doubt that greenness is a religion!
+1 Clyde. There are so many examples of useless unreliable energy examples of solar and wind, but they keep doubling down on stupidity.
Thank you, nice to know there are a few others out there that understand what is going on. Not that it matters though because there are so few of us. Witness the responses to the fraud filled election that will bring us lots of $+/KWH from Harris/Biden/Kerry,
Can power electronics now create power from nothing? Extremely fast. 🙂
If they misapply feedback analysis to the power electronics in the same way that it was misapplied to the climate system, then apparently, yes.
I seem to be missing something; where are these inverter- based resources located that are going to be tapped into for the fast frequency response. They wouldn’t be needed if the cause of the problem, intermittent wind and solar wasn’t there, in the first place. If there is a problem aren’t they existing in the same area as the problem?? If not, then again a lot more investment and cost for no reason.
skiman December 13, 2020 at 9:07 am
… . They wouldn’t be needed if the cause of the problem, intermittent wind and solar wasn’t there,
—————
What backs up your grid when a 500MW turbine throws a blade, or your 500MW nuke decides to scram?
Wind dies slowly, a WEC of 7MW dying in milliseconds would hardly be noticed. (An electric train accelerates using 7MW and brakes putting an extra 7MW back onto the grid). All this handled without problems.
Speaking of hypothetical situations, likely or not, what happens in the far more likely case when you have a couple of days in a row of cloudy weather, no wind or both?
“Wind dies slowly”
This is not necessarily true. I have seen a passing storm front take the wind from calm to windy very quickly and after the storm front passes it can drop back to calm very quickly. An especially ironic case of the sudden loss of wind power is when the wind increases above the cutoff speed of the turbine causing the turbine output to suddenly goes from maximum output to zero and stay there until the winds dies down again. The cases would not affect just one turbine but instead they would affect whole wind farm(s).
Did the wind simultaneously die 20km away in direction of wind?
wind at 30mph is .0134 km/sec so wind will continue for 24 secs 20km away
The benefists of distributed generation
“Did the wind simultaneously die 20km away in direction of wind?”
Yes the wind could also be gone 20km away as that is not all that far for a weather system. And even if it wasn’t, losing one or more wind plants is a potentially crippling loss if your grid is dependent on wind generation even if there are other wind farms still running 20km away as there is no way to throttle them up to make up for the lost wind farm(s). The harm from being dependent on unreliable wind generation.
Like in 2016, when all of South Australia’s wind turbines decided to shut down for safety reasons when the wind went over the safe level. 100% to 0% in milliseconds.
Once the grid reaches the point where most of the power is being produced by renewables, even if only 10% of the wind turbines shut down because the wind has dropped, what are you going to replace that power with?
Now the same scenario, except 100% of power is being generated by renewables.
“Did the wind simultaneously die 20km away in direction of wind?
wind at 30mph is .0134 km/sec so wind will continue for 24 secs 20km away”
WRONG !! Once the pressure difference is normalised, the wind stops ALL the way between
Like water in a pipe. You turn off the tap.. the water stops flowing.
In a typical grid, none of the generators are running at 100% capacity. This if one shuts down unexpectedly, the others have reserve capacity to replace the lost power.
When the wind dies, it dies everywhere. When the sun goes down, it goes down everywhere.
No, not really. You may put in 7MW for acceleration, but you don’t get back 7MW from braking, unless you don’t care about passenger platforms and signals. Most trains braking systems are a combination of regenerative and rheostatic braking and all of them include air braking and many times many other forms of braking. So, depending on the speed and passenger loading the brake system is a blend of many forms of braking .
How many times does a change in wind speed impact only one wind turbine?
If there was only one wind turbine, then it could shift in and out without bothering the rest of the grid.
In case you’ve forgotten, the goal of the climate alarmists is to replace all power generation with wind and solar. In such a case, you would be talking about 30% or more of the grid dropping out in a matter of minutes.
I don’t understand the rationale for your reply to my question to bethan 456. You asked a question ( answered down post) that has little to do with the issue at hand, frequency of the grid. My issue is simply how does a grid under frequency stress fix itself by using the same components that cause the stress in the first place.
skiman, like most progressives, ghalfront is very skilled at changing the subject when he can’t answer a question.
Please refer to my reply some number of comments above. You have not quoted the conclusions of this section of the report.
You’re missing the point. With fossil fuel and hydro energy, immediate changes in demand are taken up by the rotating inertia of the turbine and then shortly after by increasing the energy input to the turbine by opening a steam, gas, or water valve. Ultimately the energy input has to be increased. While grid stability when demand (or supply) for renewables changes can be managed by power conversion electronics on storage for a *very* short time (as grid storage is miniscule) there is no valve that can be turned up on wind or solar to get more power. Without fossil fuel backup, unreliable renewables will need thousands of batteries each larger than the world’s largest to back them up and ensure grid stability. The world’s largest battery at the Hornsdale power reserve in Australia cost about $100 million and can supply a very small 70 MW for only 15 minutes or (an even smaller) 30 MW for 3 hrs – nowhere near enough energy to get even one small utility through the night or past a calm period.
The engineers know it is a thing, but what causes the “galloping” of the high-tension wires on the towers behind my house during high humidity/frost conditions ?
~235,000 volts.
Would I get a shock if I threw a wire lined fishing line up and over said powerline ??
(I know better than to try this at home), just curious.
Ever see a bird perch on such a line? What would be the potential difference between beak and claw?
They approach them and almost land then shy away.
Seems they definitely find the electric field uncomfortable. That could be (safely) tested in a lab.
Smart birds!
”
What would be the potential difference between beak and claw?”
The voltage difference between the beak and claw is zero. Now if the bird landed on one wire and the beak was very close to a second wire There would be a voltage differential between the beak and claw, current would flow between the two wire an the bird would be instantly killed. you need current to flow to kill the bird. So if the bird lands on one wire and is not close to any other wires the birds wouldn’t notice anything different than a branch.
utilities actually do wok on transmission line with the power on.
Also: “Replacing conventional generators with inverter-based resources, including wind, solar, and certain types of energy storage, has two counterbalancing effects. First, these resources decrease the amount of inertia available. But second, these resources can reduce the amount of inertia actually needed—and thus address the first effect. In combination, this represents a paradigm shift in how we think about providing frequency response.”
..
..
Reference: https://www.nrel.gov/docs/fy20osti/73856.pdf
Experience says different
ERCOT doesn’t seem to have an issue with all the wind they integrated into their grid.
Texas isn’t trying to shutdown natural gas-fired generation either. Texas also has 2 nuclear power stations with 4 large reactors pumping out power. The Stupid Dementia Joe and Commie Harris Admin willl try to force Texas to shut down nat gas and coal plants though. But Texas and its governor will give the Washington DC eco-Libtards the Big Middle finger.
South Texas Nuclear Generating Station (2 × 1280 MW, 84% capacity factor) and Comanche Peak Generating Station (2 × 1210 MW, 88% capacity factor) in conjunction with dozens of natural gas and coal generation plants around the state ensures ERCOT can manage the Texas grid, which is largely isolated from the rest of the US.
Texas isn’t trying to replace all of it’s power with wind and solar. They are keeping them at a low enough level that the fossil fuel plants are still able to provide grid stability.
Exactly. Wind is just a supplement. They can easily integrate a bit of it without the problems described by Rud.
Actualy the problems described by Rud still exist even when wind and solar only provide a percent or two of total power. It’s just that when the presence of renewables is small, the rest of the system is able to compensate for the instabilities caused by them.
In addition to the frequency problems, you also have the problem of the fossil fuel plants not being able to reduce their power output at all, so that they will be available to replace the power from the renewables when the renewables inevitably drop out at unexpected times. This why renewable power always makes electricity more expensive.
When everything is working perfectly, the grid is able to handle the instabilities being caused by a small amount of wind/solar. The problem is that in the real world everything does not always work perfectly.
Every decade or so there seems to be a major power outage that is caused by a series of unusual events, all occurring at the same time.
By adding yet another source of instability to the grid, renewables make it easier for a string of random events to bring down the grid.
The only alternative is to spend the money to make the rest of the grid even more robust.
bethan:
From one of the links you provided:
“The costs (or need) to develop a system that can reliably operate under near zero-inertia conditions has yet to be analyzed in detail, particularly in comparison to maintaining the current synchronous-based system with sufficient modification to accommodate very high levels of VG penetration. ”
This document is very confusing. It conflates short-term load support with frequency stabilization. They are related but they are not interchangeable.
Zero-inertia generators really don’t reduce the need for inertia to maintain frequency in the electrical grid. In fact, they are synchronized *to the grid*. If the grid fails, e.g. a blackout, there will be no grid for the zero-inertia generators to sync to. They do offer the opportunity for fast-response to load changes but in order to do so they have to be run at less-than-full output in order to provide overhead capability. That means they will be even less efficient than most studies assume.
The concept of reactive power due to inductive loads placed on the grid are not even mentioned here.
Bethan apparently imagines a grid where only resistive loads are placed grid, with no concept of big motors for pumps, compressors, and fan motors doing their inductive thing to voltage and current phases.
Libtards like bethan456 do not understand the basics of reactive power versus active power because they cannot “do” the complex math that controlling an AC grid with inductive loads on it requires.
Reactive Power is a hard concept even for those in the industry. The idea of balancing inductive and capacitive loads when most people do not know the difference or even that such things exist makes discussion almost impossible.
I skimmed the paper referenced . A key takeaway was the mention in the executive summary (point 6)( also 7.3.1 of the main paper) of targeted load shedding of “fast responding non critical loads” suggests the idea is sacrificing some industrial/commercial reliability to protect residential reliability.
Robert,
+1
Joel,
All traditional, synchronized generators are set up to prove positive reactive power to the grid, to help transmission from A to B. Grid operators insist on it.
Wind takes reactive power from the grid.
In rural areas with weak grids, a $10 million, synchronous-condenser system needs to be added to a, say 65 MW wind system.
The SC system is set up to provide positive reactive power, per requirement of the grid operator.
In Vermont, the utility was squawking, but had to comply, as it would otherwise be kicked off the grid.
Our pro-RE, Socialist Governor made “constituent-service” phone calls, but gave up.
Prior to installing the SC system, the utility had to curtail, to avoid crashing the northern VT grid.
Wind power is unpopular in Vermont, even among utilities.
And Vermont is not a big manufacturing friendly state. Next door is though: New Hampshire is very manufacturing friendly.
New Hampshire: Sig Sauer (making small arms, guns) is a very big and growing much bigger employer in NH. Other defense industries like Raytheon and BAE are there too.
Sig’s manufacturing processes are very heavy machinery (big lathes, die stamps, big fans, ovens, lots of inductive loads) dependent. Sig has big, big DoD and foreign government gun contracts. They are running 24/7 ( 3 shifts) to keep up with small arms demand and they still need more machinists, and experience CNC operators.
I expect NH to go Big Red in the 2022 election as the Biden-Harris Admin try to both destroy affordable electricity and destroy the small industry, both big items in New Hampshire.
For which reason, I deliberately avoided any discussion of AC reactive power except for one sentence concerning reactance as property of AC impedance, the AC equivalent of simple DC resistance.
Is the sine wave phase problem represented by the imaginary number i in complex a+bi math. But WUWT is a blog where many commenters apparently do not even know the difference between DC and AC electric current So clear but still ‘accurate’ simplifications are necessary to address most here.
“… certain types of energy storage …” Such as?
With fossil fuel plants, as soon as the turbine starts to slow down, more steam can be added to return the turbine to it’s proper speed.
How do you plan to apply more wind to a wind turbine so that it’s speed can be restored?
Protection engineer here, I’ve always used ~99% as propagation constant in EHV transmission lines. I think your 61% is more appropriate for coax-like conductors (ie underground cable).
Sounds about right – at radio frequencies, velocity factor for open wire line is usually assumed to be about 95%. OTOH, electron drift velocity might be on the order of centimeters per second.
Josh, your emf propagation wavefront constant is about right, depending on the conductor. Something close to but below speed of light in vacuum.
But my challenge was not about the emf wavefront propagation speed in a conductor, it was about the underlying electron physical motions in that conductor that enable it.
I lived in the UK in the 1940s and early 1950s. “Brown outs” were notorious, as the demand in the day resulted in a substantial drop in frequency, perhaps 2 or 3 HZ, and electric clocks ran noticeably slow. This was balanced during the night, when demand was low, and the grid caught up with time. A country wide grid, and frequency variations were normal.
Note 230 V AC lights are noticeably dimmer when operated on 210 V. The converse is when we were in dry dock in Calcutta, and were supplied by shore power – a diesel generator supplying 220 V DC. The speed control on this was rather erratic, and sometimes the lights would go very dim. Also, sometimes the lights would go very bright, and we would hear ‘pops’ all over the ship as bulbs blew. Another ship operated on 60 Hz AC, all except the winches, which were DC. To get the DC we had a very large converter. When this was switched on the massive electrical demand caused the AC frequency to drop – not good if one was recording a good bit of music over the radio!
My late wife and I were shown over the Tumut Power Station of the Snowy HEP in the late 70s/early 80s. Engineers on duty at the station remarked that they always knew when “Country Practice”, a favourite soap opera, finished, as about 2 million housewives got up and turned on the kettle for tea. The voltage and frequency drop opened the sluice gates at the power station and the hitherto idling turbines were suddenly deluged in a massive rush of water, as voltage was restored.
Renewables are OK when you have a lot of coal or gas fired power in the system.
“Basic grid electrical engineering (EE) is simple and inescapable concerning renewables— they are uneconomic (investment always falls when subsidies dry up), intermittent (requiring underutilized backup generation), and provide no grid inertia (which is automatic with big fossil fuel fired generators). ALL BAD.”
gh
Inertia of rotating machines is high but since the frequency must be maintained they soon run out of synchronism
the uk nuclear industry is loosing capacity because no one wants to invest in stations. Hinkley C is to be subsidised by loans and 1.5* current grid /kwh price.
——
The US is designed to be a stable 60 Hertz, EU 50 Hertz. Because electric clocks depend on grid frequency, ‘stable’ is about plus/minus 0.2Hz in the US
——————-
gh
This is just tosh.
There are some clocks that require stable frequency but average accuracy is enough How many mains synchronous electric clocks still exist?. Transformers, some motors etc require a semi stable frequency. The frequency falls on high load and rises on low. 0.2Hz seems to be the normal deviation allowed even on 50Hz. A document for a failure (1.5GW generation lost) showing frequencies:
https://www.ofgem.gov.uk/ofgem-publications/41426/nationalgrid-systemeventsof27mayfordswg16july.pdf
————–
Skipping a bit of complex math explaining very simple physics, the reason you buy ‘fat’ DC audio cables with gold terminals is simple: DC current flows across the entire conductor cross section fairly uniformly. A fatter cable has uniformly l
—————-
gh
speaker signals are not dc. This is why some audiophiles use litz wire – hig frequency only travels in the outer skin of cable. However a famed uk producer of high end speakers was aske what cable was used to demonstrate their speakers – apparently 2.5sqmm mains cable!
————–
The much more common (cheaper, lighter) aluminum HV transmission conductor is only about 61% of copper.
———-
gh
possibly but much of weight is made from a steel core for strength
People have even talked about using sodium (very light) as the conductor and were trying to think of a way of stopping explosive oxidation!
I have a nice bridge to sell you ..
I love a zero-frequency music from my speakers. Very refreshing, and free.
ROFLMAO..
the half-runt gets it wrong again.
The heavy cables in car audio are used for supplying DC voltage to the amplifiers, dummy !!
fred
this is from the posting
“fatter cable has uniformly less cross sectional resistance (DC speaker output is analog), and gold terminals lower connection resistance further since gold doesn’t corrode. The result is truer high frequency pitch amplitudes. ”
This is speaker cnle they are talking about – NOT DC power.
correct Mr gh. I wouldn’t worry about shouty man
YAWN
another ignorant twerp.
The big thick cables are for POWER DELIVERY to the amplifier.
What half runt did get right is that speaker wire is NOT the big thick POWER SUPPLY wires that carry the POWER to a car amplifier.
The only “fat” DC audio cables are the DC POWER SUPPLY ones.
So the statement
“the reason you buy ‘fat’ DC audio cables with gold terminals is simple: DC current flows across the entire conductor cross section fairly uniformly.”
was totally correct..
You want to maximise DC supply.
The comment did not mention “speaker cables”… that was half-runt little invention.
And a new idiot/troll doubles down of half-runts ignorance….. well done , Aye ! 😉
ghoulfont has a mini me.
YAWN…… doubling down on ignorance, the half-runt way !!
The big thick cables are used for POWER connection to the amp.
Because it is able to deliver a more constant Hi-AMPS POWER, the amplifier is better able to control the output….
So NO, it is the DC SUPPLY CABLE they are talking about.
sorry you don’t understand…
…. but why comment if you don’t understand, thus PROVING that you are ignorant.
I repeat:
“fatter cable has uniformly less cross sectional resistance (DC speaker output is analog), and gold terminals lower connection resistance further since gold doesn’t corrode. The result is truer high frequency pitch amplitudes. ”
I have to admit “dc speaker output” is a bit covfefe
Ontario is another case of renewable foolishness. The Canadian tax payers subsidize huge wind “farms”. Whenever the wind does actually blow at the correct speed, they dump power into the grid at well below cost and give Michigan utilities almost free power. When the wind stops, the same utilities sell power back to Canada at the spot market price. Great for the Michigan utilities; not so great for the Canadian consumers.
As part of the scam some of these Ontario operators were given feed-in tariff rates of 84cents per kw h in a province where power nominally costs 10cents
So they get that money even if the hydro guys have to pay Michigan to take it
Parker Gallant outlined this fiasco in a series of columns in the financial post years back, 10’s of billions wasted for nothing
Rud Istvan,
Your write-up is crystal clear on all points.
It is hilarious teachers in high schools aver electrons are traveling around a circuit.
The naive students lap it and repeat it the rest of their lives, setting them up for eternal stupidity, at least in that aspect.
They think, if it is generated in the state, it is used in the state.
They have no idea electricity travels, as electro-magnetic waves, at near the speed of light, i.e., from northern Maine to southern Florida, 1800 miles, in about 0.1 second.
I have always maintained WIND AND SOLAR are high-maintenance cripples.
They cannot even EXIST on the grid without major help from the other generators, and maybe from much-less-costly, longer-lasting, utility-scale, custom-designed battery systems in the far future.
Germany not compensating CCGTs, that are FORCED to inefficiently act, 24/7/365, as a crutch for the cripples, is off-the-charts bizarre.
Ampere’s current elements travel around C speed.
To claim the current element is an electron is not correct.
And take 2 electrons, a Cooper pair, and presto superconduction.
So even “electrons” are not “things” rushing down a cable, with a mean-free-path of centimeters….
Interesting point about DC and AC for long distance – it reminds me of the huge battle between Edison and Tesla.
But so-called smart grids proved not very bright. Does anyone remember the Ranch at the Crooked E – ENRON, and the scandal back in 2001?
How Enron Manipulated State’s Power Market
https://www.latimes.com/archives/la-xpm-2002-may-09-fi-scheme9-story.html
Looks like Enron managers migrated to Europe….
I’m always amused to note that the popular EV car is a Tesla, named for the man who promoted AC.
I’m not sure why Retired_Engineer is amused a popular EV is named TESLA… the motor is 3-Phase. Nikola would be pleased.
Listen to the Formel E races – the motors scream at high rpm’s.
But the battery (which those guys swap at pitstop) are DC.
I think Musk is inspired by Tesla.
bonbon
It is my understanding that the EM field that displaces electrons in a conductor travels at a speed inversely proportional to the dielectric constant of the conductor. However, an electron from a battery in a New York City telegraph office is not the same electron that drives the telegraph in the Calcutta office. It is not even one of its initial neighbors. Think of the desktop pendulum novelty where a ball smacks into several others, and the one at the far end is the one that moves.
The EM field travels at a velocity that is inversely proportional to the square root of the product of the relative dielectric constant and relative permeability. The first inkling that light was an electromagnetic phenomenon was when the velocity of propagation predicted by Maxwell’s equations using the permittivity and permeability of free space was equal to the velocity of light.
You may wish to revisit your audio references. Speakers, when powered with DC (you can easily test this for yourself by connecting briefly a 9V battery to your speaker cables), the speaker cone moves in ONE direction. In order for your speaker cone to move both in and out, producing what some may call music, it requires an alternating current.
As far as heavier/thicker/whatever speaker cables are concerned, there are tradeoffs, which is but one reason many high-end monitors have built in amps. .. Bringing us to the “gold is better” hype.
After doing extensive critical listening direct A-B tests in a record company’s reference room there were some very surprising observations about gold cables and connectors… None of which caused anyone associated to go out and buy, much less convert, to gold.
Gold is great. Silver sounds better.
In many cases, the speaker is powered by pulsating DC, not AC.
In a way , yes, but not.
Most amps (class AB) have a dual circuit, one provides the top half of the signal, the other provides the bottom half.
So while each part could be described as pulsating DC, the combined signal looks more like a complex sin wave.
Now a D-class amp, it is closer to DC, using pulse width modulation to form the signal to the speakers.
Its getting too complicated nowadays, with new class G & H which uses the signal to switch (G) or modulate (H) the voltage on the supply rails.
Every tried braided Cat5 cable .. ultra low Inductance.
3 lots of Cat5, separate the whites as -ve and colours as+ve at the ends, then braid the 3 Cat5 cables together.
Terminate with high quality gold.
Super low inductance.. Tried a pair against some QED silver, of the same length
A group of like minded audiophiles put them to the test. We all thought the braided Cat5 won.
The link to the original “science” yields a “500 Internal Server Error”.
Sorry about that. I just duplicated what Charles provided. Worked for a pre draft download.
Rud, the link I sent you did not end in phg.
Here is the link.
https://www.eurekalert.org/pub_releases/2020-12/qmuo-spo120920.php
And the post is corrected. You could have called me.
Simply put, Cos(φ) has no more any meaning in modern grids. Simply because those grids are over polluted by about any harmonics and present the summary of many sine signals, each with it’s own frequency, phase and amplitude.
Now, Cos(φ) is defined for a sine wave as the phase difference between voltage and current. Therefore each harmonic has it’s own Cos(φ), largely dependent on the grid configuration (think Impedance), generator characteristics and consumer loads.
Reactive power is whatever flows between generator and consumer without doing any real work.
Management of reactive power is a key factor for grid voltage stability, achieved by Cos(φ) management.
Which in the context of a vast multiplicity of inverter type generators (like windmills and solar stuff) becomes a guesswork deal at best.
EU has legally limited to 750 Watts (and decreasing to 450W in the future) the power of household vacs. Officially to save the earth or something.
Under the hood, a different reality. Unmanaged use of a huge number of small powerful largely inductive loads can wreck havoc on the already seriously unstable EU grid.
Yes, most people only think of the grid as power, which does work.
But without adequate VARS the network collapses, hence capacitors, synchronous condensers.
In large oilsands plants (essentially a small distribution utility) under some circumstances they are limited by vars instead of watts and so we have different load shedding schemes depending on the limitation
“Tesla first envisioned AC generation by using complex numbers (a+bi). ”
Is that true? I thought Steinmetz introduced complex numbers into the analysis of AC.
DAJ
I think that Steinmetz is a very much under-appreciated genius.
I believe Steinmetz gave electrical engineers the mathematical tools they need to design ac, and radio systems.
Rud
I think in your headline post describing GTs, you are confusing droop with inertia. Inertia is a fundamental property of the generators from its moment of Inertia and rotational speed. Conventional coal plant has more inertia than CCGTs which has more than OCGTs for the same MW. This is because on GTs, not the whole train is locked into grid speed, only the power turbine and generator (and steam turbine for CCGTs). CCGTs at low load often have less inertia because the steam turbine is clutched out. With a convential steam turbine at low load (this includes nukes as well as coal fired plant) all of the train is spinning at grid speed and locked into it.
Droop is the governor response of a unit to a change in frequency – how much the load will automatically change as the frequency goes up and down. It is usually expressed as a %. Most machines are around 4-7%. That is for the biggr number, a 7% rise in frequency will take the machine from full load to no load (or the other way around if the frequency drops. This is where GTs are good as they can have a very fast response time, whereas conventional coal / boiler plant is slower as you need to keep water in the drum. For a lot of operational management reasons, many machines don’t run on droop control, especially for underfrequency. This can be because of environmental reasons where pollution control is a lot harder during transients.
There are 2 types of droop, frequency as you stated above and voltage drop via the avr which allows power factor sharing across generators.
I tried to limit my mention of voltage as it wasn’t directly relevant to the OP, but yes, the Automatic Voltage Regulators (AVR) change both the voltage and phase angle. However, once that starts being mentioned, most people’s eyes glaze over.
So add another expense and failure point to wind power as you increase use.
As I deal in electrical protection and control I am very up front about what renewables do to the grid and how that helps my business even as I know it’s the wrong path.
I have no intention to do an “Al Gore” and get rich AND state I believe in something.
Adding renewables requires extremely high speed comms networks and control ideas like synchrophasors in order to attempt to manage it.
The intermittent ruinables have no inertia, and so they reduce the elasticity of the grid, increasing flicker as large motors are started hence the need for soft starts and VFDs to limit these grid shocks.
All this foolishness is nonetheless good for my business
Well Pat what can one do;
When in Rome…
Another linked issue is the reactance of generations – How many VARs they produce. This is the “invisible” component and why generators and transformers are rated in MVA, not MW. . The generators can have their current lead or lag the voltage (this references the peaks of the sine waves) As others have noted, this is to try to keep the grid near unity, improving efficiency. A similar task is also done by capacitor banks in switchyards.
The grid normally needs VARs at times of light load and wants negative VARs at heavy load.
For generators, changing the rotor current changes the VARs and this can be done automatically. However, there are limits to this. Too many VARs makes the components run too hot. Too many negative VARs and pole slip can occur.
If the frequency of a grid decreases, that means the generators are spinning more slowly. That means they should be making less voltage. That means the load gets less power. So, there should be some kind of equilibrium. yes/no?
I have a very dim memory of a lecture about electric motors sharing a mechanical load. I guess that the same kind of issues affect generators.
It’s a bit more complex. Let’s assume my “office” is a grid and each engine a generator.
I can throttle down number one, throttle up number two, give some pedal and keep going straight, level and steady. However, number two will run a bit hotter.
Playing this game further without altitude/speed changes could (in theory) lead to shutting down number one and overcooking number two, then, eventually run out of rudder authority and spin down.
This could hypothetically happen if the autothrottle has issues and slowly drifts in a deep yet unnoticed power unbalance. At a point in time, the autopilot would brutally disengage due to lack of authority and throw at us a barely flyable but otherwise perfectly good airframe.
Which is why, two or more independently self-regulated generators without a central authority are a cookbook recipe for disaster.
Each regulator has tiny barely noticeable errors. There’s no regulation without error. And such errors, in time, shift into a paradigm where some generators overwork while others go idle.
Unmonitored by a central authority, this leads to a “domino network” blackout.
Monitoring tenths of thousands of generators (solar stuff, windmills) is one of those problems where combinatory increase of possible scenarios starts to really matter.
That’s why it’s not even attempted, leaving local grid dispatchers on their own. Until a critical number of generators fail due to overload and the grid collapses.
Both the frequency and voltage are separately controlled with drop characteristics to enable multiple generators to be run in parallel.
Interestingly, when I attempted to read the original EurekaAlert article at the link Rud provided, I got the following warning from Firefox:
“Firefox detected a potential security threat and did not continue to eurekaalert.org. If you visit this site, attackers could try to steal information like your passwords, emails, or credit card details.”
I guess that is just a more direct way to Rob you blind
Cheaper too, direct you to a webpage, as compared to the cost of installing all that useless renewable power
I guess it was only a matter of time before the green slime cut to the chase
For grids at a given power loading, there will be a frequency (and voltage) change when there is inbalance, which is near all the time. A high inertia grid slowly changes, low inertia rapidly changes. The units of inertia are often MW seconds. Slow is best. This gives time for the machine on fast response to change their loads, the usual droop control. This is a function grid batteries can do very quickly.
When you get a very large inbalance, like a large generator tripping off, high inertia gives time for protection to work before load shedding starts. That is why South Australia went black in 2016. Low inertia, big power line tripped out and the frequency dropped too qquickly for protective load shedding so everything shut down. Welcome to the unreliables future.
Grid batteries will be hugely expensive and damaging to the environment, but are only needed due to the known deficiencies of renewable power
Why spend trillions to apply bandaids to an already broken system ?
A system broken by design.
Pat
Yes grid batteries essentially are there to cure a problem caused by the solar and windplants on the grid. They generally wouldn’t be needed if those unreliables weren’t there. They can be useful for voltage control at the end of long lines with varying loads, even on a conventional grid.
However, one has to acknowledge good points of plant, even if they are overpriced for what they do.
A couple of minor corrections to Rud’s post:
Use of complex numbers to analyze AC circuits is usually attributed to Steinmetz.
At least in years past, a substantial amount of the load on a grid was composed of synchronous and induction motors, both of which provided inertia (more so with synchronous) and a frequency sensitive demand. I suspect the trend to variable frequency drives is also decreasing grid inertia. One way to at least get some damping is to make EV battery chargers respond to frequency.
Fifty years ago, the operational rule for Ontario Hydro was ‘The provision of reliable power from adequate generation at cost’. The benefits were one of the lowest wholesale cost of electricity rates in North America and the associated economic uplift in all areas of the Ontario economy. Ontario now has one of the highest industrial and retail electricity costs in North America thanks to the rape of the ‘electricity market’ by vested interests in so called ‘renewables’. The plethora of confounding dispatch rules and reliability constraints has most system operators turning themselves into pretzels in order to manage contingencies and disturbances. The old rule really was the ‘good old days of grid management’.
This site (already mentioned above) for the US PNW:
https://transmission.bpa.gov/business/operations/wind/baltwg.aspx
. . . shows what is producing, or not, now and for the previous week; updates every 5 minutes.
Have a look.
Note that wind is shown by the green line that bounces up and down near the bottom. There is a brown line representing 50 or so thermal facilities. The purple line is a single nuclear facility (Columbia Generating Station). There were minor dips in both thermal and nuclear in the last 24 hours (now Noon on the 13th). I haven’t looked to see why.
Wind peaked a few days ago. Note that as wind went up, the blue line dips – that’s hydro (lots of big dams in OR, WA, and ID).
So, at Noon on this gray Sunday, the wind turbines have no blades spinning, and haven’t had for awhile, thanks to the big LOWS out in the North Pacific Ocean, and the big HIGH over the adjacent land.
See – – earth dot nullschool dot net
– – to see the wind patterns.
Central Washington State has wind = 0 mph.
But they’re going to compensate for all those non-producing wind mills by building so many more non-producing ones that they’ll catch up… the wind is always not blowing somewhere.
“electron could travel in its aluminum high voltage skin is about (1.95/60) 3.2 cm”
What a nonsense! Certainly not.
Each electron travels to the next atom only (classical view), where another electron takes over.
In a quantum view, it is more complicated, as there is no individual electrons anymore.
But let us stay classic.
The skin depth in Copper is about 8.5 mm at 60 Hz. Thus, the 60 Hz current flows in the bulk of a 1 cm wire.
Free electron density in Copper is about 1e23 1/cm3
The electron velocity in the Copper is then v[cm/s] = J[A] / S[cm2] e[C] n[cm-3] = J[A] / 1cm2 1.6e-19C 1e23cm-3 = J[A]/1e4 cm/s (S is the crosssection of about 1 cm2)
A typical transmission line carries a few hundred A current.
Thus, the electron velocity in the wire is about 0.01 cm/s
The electron excursion is then v[cm/s]/w[rad/s] = 0.00005 cm = less than one micron!
(w[rad/s] = 2*pi*60 Hz)
Nothing even near centimeters.
+42
I stayed away from comments to this invited guest post on purpose to see which misconceptions might emerge by commenters not researching the stuff first.
So, some misconception corrective comments about which I am quite certain, as a holder of several fundamental patents on energy storage materials and how they can be applied to both EVs, grids and wind turbines (WT answer, blade pitch control and ACPower synch rectification to about 0.5 MW). Charles handed me this assignment because he knew I knew this stuff cold despite not being an EE.
1. Wind is asynchronous so provides no grid inertia because of a fundamental: wind speed is variable, so therefore also is any wind generated AC sine wave. Wind power is rectified then synthesized to AC grid sync. The kinetic energy mass of the wind rotor blades is therefore irrelevant.
2. All home speaker systems I am familiar with use DC. If AC were used there would be an unavoidable underlying AC ‘hum’. The reason DC works is that the speaker cones that push the air based on DC energy are ‘springy’ (elastic, look at the driver part, not the cone part, if you ever take one apart. (I have repaired two old fairly big speakers at my farm by judicious use of duct tape where the driver and cone tear apart with age, duct tape just recoupling the inert cone to the driver DC magnetics.
3. Subatomic Quantum weirdness does not apply in emf bulk materials. In bulk, there are free electrons ‘stripped’ by emf, and they do move in a conductor driven by emf. Emf in matter moves still close to C, but the free electrons individually do not The emf in a DC system is volts, the quantity of free electron charges is coulombs, and the resulting product is amperes of current. By definition, 1 coulomb of charge times 1 volt of emf equals 1 ampere of current. Maxwell equations describe the resulting varying EM fields using tensor calculus. If quantum rules applied, batteries would not exist.
“2. All home speaker systems I am familiar with use DC. If AC were used there would be an unavoidable underlying AC ‘hum’. The reason DC works is that the speaker cones that push the air based on DC energy are ‘springy’ (elastic, look at the driver part, not the cone part, if you ever take one apart. (I have repaired two old fairly big speakers at my farm by judicious use of duct tape where the driver and cone tear apart with age, duct tape just recoupling the inert cone to the driver DC magnetics.
Its actually a tad more complicated
If you feed a constant AC (low voltage, please) signal to your speaker, you will get a constant sound from the loudspeaker as the speaker vibrates backward and forward. If there is no AC signal.. no sound.
If you feed constant DC to a speaker (1.5V max for a second or two, please) you will get a slight pop as the driver moves either backwards or forwards. If you leave the DC connected, you will eventually get smoke and an dead loudspeaker.
So no, not DC. Usually modulated AC drive from the amplifier with a very small DC bias (up to 15mv)
Inside the amplifier, there are both AC and DC sections. gets complicated from there. EE’s only !!
Its really all a matter of terminology……. and shades of grey.
“DC is generally understood to be constant, and AC in most uses is generally understood to be a constant sine wave. Audio signals really aren’t either.. Audio signals are varying sine waves in the frequency range of 20 Hz to 20,000 Hz. A constant AC signal (meaning of constant frequency) within that range would be called an audio frequency AC signal though. There’s enough weaseling within the common use of the terms that you could easily get away with calling audio signals AC. You just have to be careful of the context. “AC” to many folks means 120/240 volts AC 50/60 Hz. It’s more common to just refer to audio signals as “audio” instead of trying to call them AC or DC.”
“The reason DC works is that the speaker cones that push the air based on DC energy are ‘springy’”
Speakers have a outer surround (usually rubber, or similar, for long throw and Hifi drivers, and corrugated clothe for PA style drivers) They also have a corrugated voice coil alignment “spider”.
The cone vibrates backward and forward about a central position. Certainly NOT DC
Without that vibration….. No sound.
Take a 1.5V DC battery, and use it to “test” a speaker (don’t use 9V !!.. and only do it for a second or so.)
You will see the speaker moves one way only, then returns to center position when you remove the voltage.
Yes audio output from class B & D amps is AC. It is not a constant frequency like AC power but it is a constantly changing combination of frequencies and harmonics in the sound of human voices and musical instruments. It still merely pushes and pulls on electrons with no net DC current, creating an electrical transmission wave similar to AC power transmission. Class A & A/B amps have a DC bias. This DC bias makes them less efficient (these amps often generate more heat than audio power) but they may have cleaner audio (lower THD) due to operating in a more linear fashion. However the DC current component does not really require having “monster” cables to have good quality AC audio.
At one time, cheap audio amps used class C and expected the speaker to do as Rud says “fill in the gap” thru its springiness. Muddled audio was the issue. Even today the springiness in speakers leads to muddied audio. Proper damping is an issue and in usually can’t be done properly over a large range of either frequency or power. That’s why quality high power speakers cost your arm if not your leg too.
Big cables are used for a couple of reasons. The big one is power. A 400 watt speaker requires a lot of current with a 8 ohm load. Lots of current which is what causes a skin effect, not frequency. The current also requires a big cross-section to reduce ohmic losses. And lastly, is the damping it supplies back to the amp.
Big thick speaker cable have too much inductance, his affects the top end sound.
Ok for bass usage, but not on a full range loudspeaker.
Some comments:
1. Wind power can supply virtual inertia, if the electronic control system is prepared for it. It may be a must in the near future. In addition, it can provide some primary reserve to adjust the frequency and it has been started using in the UK.
2. The output of an audio amplifier and a connection to a speaker is AC. A good high fidelity system covers a frequency range of 20 Hz to 20,000 Hz. The impedance of the speaker is usually 4, 6 or 8 ohm and to avoid voltage drop and deviation of the frequency response, the connecting wires must not have an impedance greater than 5% of this value. That is the reason for choosing stable low impedance cables and connectors.
3. To say that “1 coulomb of charge times 1 volt of emf is equal to 1 ampere of current” is totally wrong (it’s energy, joule). The electric current is the charge flow (coulomb per second).
4. In a large interconnected system it is important to check the possibility of inter-area fluctuations (to avoid dangerous inter area oscillations), to evaluate a rate of change of frequency (it is used for automatic load rejection) and, as the interconnected system is a common good, to check the solidarity of response from partners (primary reserve triggered by this first frequency regulation system – due to the frequency droop control by the generators equipped with such installation). If the article is a contribution to help in these fields is welcome.
2. All home speaker systems I am familiar with use DC.
….
You are dead wrong on speakers using DC Mr. Istvan.
…
A positive voltage pushes the air one way, and a negative voltage pulls the air in the opposite direction. The voice coil is suspended mid way in the field magnet.
Oh dear
Oh dear oh dear.
i have an honours degree in electrical engineering.
I am embarrassed on your behalf.
Lets let it go at that shall we?
Please be more specific, since you are apparently so much more well educated.than I.
What part of my laymen’s AC no math explanations do you find so ‘oh dear’ distressing as a likely troll subject ‘expert’?
Just ignore him Rud. A number of years ago a friend of mine showed me around the water treatment plant that he managed. It was a ten or fifteen minute tour and at the end he said I knew more than the guy with the relevant degree that had worked there for just over two weeks. There were three major flaws in the site
What a clever little boy aren’t you. :((
You could have proved it by showing where Rud was wrong but you chose to be a prat instead.
If the initial cause of the frequency instability was due to a drop in output from wind turbines, how wise is it to depend on the wind turbines to create the necessary inertia to keep the grid from collapsing?
I think there might be something wrong with the “nonsense” link in the first sentence of this post.
There is a very relevant document produced by the AEMO called” INERTIA REQUIREMENTS METHODOLOGY INERTIA REQUIREMENTS & SHORTFALLS” I haven’t linked to it as I have it as a pdf but it’s on the Interweb. They set out how they determine the inertia requirements of the Australian grid on a State basis and define how much inertia must be on the grid. There is a very good explanation of why grids need inertia and the other associated supports.
For the benefits of the bethans of this world who think the Googling up a few papers and skim reading them make them an expert, AEMO make the following statement:
“3.1.4. Asynchronous generation
On the other hand, asynchronous generation technologies, such as modern wind turbines, solar inverters and batteries, are connected to the power system via a power electronic interface and do not bring any inertia naturally to the power system because they are electrically decoupled from the power system. Most modern asynchronous generation technologies can be designed to provide frequency control capability in the same fashion as Synchronous Machines, however, most existing and committed asynchronous generation in the NEM has not been designed with this capability.
Because of a lack of inherent inertia, these technologies are currently limited in their ability to reduce a change in power system frequency immediately after an imbalance between supply and demand.”
But then, what would AEMO know? They only have to manage a grid where the unreliable renewables are causing major problems.
Here we go again
Cloudy day over parts of Australia’s east coast, Solar output low
South Australia’s wind only providing 340Mw
SA having to use 80% GAS plus imports.
Tasmania earning money feeding into Victoria.
Prices climbing !
Let’s see what its like in a couple of hours, once the Sun goes down on the east coast
THANK GOODNESS for COAL and GAS. ! (and a small amount of hydro)
“Grid inertia is just the frequency stabilization that comes from the kinetic energy of large rotating generator masses. ”
I think claiming to cover “grid stability basics” and only talking about the small momentary fluctuations that happen and missing discussion on what happens when a suburb drops or comes online is missing the biggest stability issue grids face.
In that case any claims “The gas turbine power reaction time is literally about a second no different than a jet engine.” is wrong and misleading. Ramp times are real and important. And missing from this discussion.
Tim
I disagree with your comments about grid stability. If the system is high inertia, then the changes are a lot more gradual, be they big or small. And it is inertia that determines the big RoCoF the accompanies inbalance, especially the big ones. Having a high inertia then allows the fast response and governors to kick in. Best shown in the standard grid response drawing like here. https://www.researchgate.net/figure/Time-intervals-of-frequency-response-during-a-contingency_fig6_330378952
Rud is wrong about ramp times but not by much. The classic is places like Dinorwig that can go from pumping to 1800MW in about 10 seconds IIRC. GTs and the like are slower, but even they can react at about 10% load increase in a similar time period.
Of course its all relative. A “suburb” may be only a small fraction of a grid, but that’s not the point. The point is how the grid responds to a large, long term change is an event likely to take the grid down. And they certainly happen. But modern grids are becoming more resilient to those disruptions not “despite the non-dispatchable generators”, but because they exist.
Compared to the US, UK or even Australian grids, our (New Zealand) long and stringy grid is prone to large frequency swings, even with high inertia. We usually get several 1Hz drops a year and have had a 2.5Hz drop in recent times. That is scary stuff. It means the engineers and operators in the generation industry are very aware of the issues and the damage it causes from the transients. Unfortunately, the politicians and decision makers aren’t, and they won’t want to know until we have a system black occurrence. To fix it will cost real money that currently they want to spend on fripperies. Here is a document from our grid SO detailing the linkage between inertia, RoCoF and protection together with the effect that high penetration of asynchronous generation will have on it.
https://rise.esmap.org/data/files/library/new-zealand/1%20Renewable%20Energy/RE8.4%20Effect%20of%20Solar%20PV%20on%20Frequency%20Management%20in%20New%20Zealand.pdf
Many people don’t seem to realise the importance of a stable frequency. Its not just keeping the clocks on time. If generators supplying a long distance HVAC transmission line loose sync, they become out of phase with the rest of the grid and can trip on over current. System operators usually run the system on VARS (volt amps reactive). The system is run at a slightly lagging power factor. About 0.9. Leading power factor leads to Instability.
What a wonderful range of mad ideas above! When the grid frequency slows there is a lot of power available from the rotating masses ( a steam generator, 600MW has about 100 tons rotating at 3000 RPM or 1500 RPM depending on design, 1800 / 3600 in the 60Hz countries) the bulk of the weight being at the peripheral diameter. This has very high rotating energy available from small changes in position (leading to frequency changes if continued). This phase change also creates very large reactive currents between the rotating machines keeping them moving together. The power involved may well be hundreds of MW above the normal generation. A wind turbine has virtually no available power reserve, and the inverter follows the phase at the machine very accurately, to avoid this large reactive power being required. If it was allowed, the blades would probably stall instantly causing severe mechanical and blade damage. The inertia in a wind turbine must be allowed to rise and fall slowly by the control system putting more or less power to the grid, in other words they have NO reserve at all.
They were already wrong at the start. Per their quote: “that will help develop new power systems capable of meeting changing demands, such as the move towards renewable energy sources.” Demand hasn’t changed. People still need power at the same times each day as they used to, unless you buy a battery-powered vehicle. The difference is that the ability to generate electricity on demand has changed from always to maybe.
For readers in Great Britain (using that designation in a strict sense),if you want to be really terrified, read
National Grid System Operability Framework 2014
The most terrifying bit is Table 7:
National Grid ran a series of these publications after that first report, but then they sort of dribbled away. I can’t think why.
The German government refuses to make up the difference, yet also refuses to let them shut down.
Ve haff vays ouf keeping you from shutting down. You WILL stay online, unt till ve say zo.