Using global control instead of local control seems like such an obvious improvement that I wonder why it hasn't been used earlier. I wonder whether the real difficulty lies in getting the simulations accurate enough to make useful predictions.
All the wind turbines in any given windfarm come from the same manufacture, and they all have monitoring and control from the utility's main offices in whatever city (at the very least they have enough control to prevent damage when the weather gets bad, I don't know what else they can do). As such all that is needed is a software update from the manufacture to give the central office more control.
The utility might own wind turbines from different manufactures, but they are not in the same wind farm. I suppose there might be places where two wind farms border each other that you want different devices, but for the most part you can optimize each wind farm individually with no need to worry about manufactures.
Sure they can, but the reality how wind farms are built is they won't buy more than one make on any given farm. They place an order from some factory to deliver, getting a into the factory order stream is a large part of the process. Of course it does take a couple years and so there is plenty of opportunity for the factory to change internals in the middle, but the manufacturer is locked in before the first turbine goes up.
Shipping is also rather expensive, so your are probably going with the nearest factory for everything. (each blade needs a semi with an oversize load permit, and "chase cars" both in front and behind with the right lights and signs)
Of course if a turbine fails in 5 years (I don't know what the warranty is, so I'm going to use 5 years) they might replace it with one from someone else, but that isn't common.
I don't know how much is onboard controls. However someone is feeding the weather instructions in, and when demand is low someone is telling a few to shut down. They also do remote monitoring for issues that maintenance needs to fix. That connection just needs an upgrade, along with some new software for the onboard controls and it can be done offboard. (this may not be easy, but compared to a turbine it is cheap)
I count an expansion as just putting up a new wind farm next to a previous one, which happens often. At least in my experience the expansions often get a different model (visually different), but I count that as a new wind farm.
I'm reasonably sure that all wind turbines in my area come from Siemans. (they have a factory in my state, any other make would be shipped in from a considerable distance)
If the turbines are close enough to impact the air flow to the other ones then they are effectively the same for the purposes of the cfd model in the parent post
It's a 1.2% overall improvement. That's the kind of number where it's worth doing in general, and worth using if it's been developed, but not nearly worth the development effort and headache for a wind farm operator trying to invent it on their own.
considering it amounts to 1.2% over a period, I wouldn't say "obvious improvement"
local maximizing presumably already deals with the effects from upstream turbines, global (also presumably) only adds consideration for downstream turbines
It has been done earlier; multiple times, by every serious manufacturer. :-]
The real difficulty lies in:
1) Noise in the on-turbine wind speed and direction measurements and/or robustly (see point #2) operating LIDAR or met masts in front of the farm to try to avoid said measurement noise.
2) Actually arriving at a robust, operational in real-world conditions, fully closed-loop control system. A commercial wind farm has to operate 24/7 for 25 years without a bunch of engineers and scientists babysitting it, which is what is likely to end up happening if the cool control system relies on offline simulation results, topographical data, and/or human-supervised calibration & tuning.
It's not all doom and gloom: Ongoing improvements in sensor price/quality will probably make these kind of global control systems more and more practically feasible in the future.
Having off-site control of configuration and sensor information seems desirable and obtainable regardless. And once that is in place it is just a commercial decision. If spending x on cloud modelling delivers a multiple of x then its a simple decision.
As the old say, the devil lies in details. Writing a global control is no means an easy task, as
1. You need to recognize the opportunities exist in the first place.
2. You need a global controller that can aggregate and optimize for a global solution (and the global solution might not necessarily simply to maximize the aggregate throughput, but there might be other factors into account), which may involve some algorithmic design (in some cases, you need to design new algorithms).
3. You need to justify that global controller gives you a superior solution compared to locally greedy solution. As in this article, a global solution gives you about 3% improvement compared to the local controller, and the local controller algorithm is substantially easier to write.
Background: in my previous job at Meta, I wrote such a global control algorithm for controlling the rate of data going in and out each data center. It involved some really interesting algorithmic design.
I think the real thing that's difficult is-- every installation is different, in the geometry of the turbines, turbine sizes, terrain shape, etc.
Even if you have a perfect implementation of this, and you don't need to deploy new networks, etc, and you put in a lot of NRE to make this easy deploy... how much engineering effort is still needed to start squeezing 1-2% out of a wind farm?
You are severely overestimating "common sense". Joe and Jane Average (and by extension various stages of planning permission in certain locations) are still saying "but what about when theirs no wind!?!? lol" as if transmission lines don't exist.
The research was definitely worth pursing. A 1.2% overall efficiency gain is not nothing, and is indeed significant enough that I think people will want to implement it.
On the other hand, without doing some extensive research, it wasn't clear what the magnitude of the improvement actually was.
"But in the new system, for example, the team has found that by turning one turbine just slightly away from its own maximum output position — perhaps 20 degrees away from its individual peak output angle — the resulting increase in power output from one or more downwind units will more than make up for the slight reduction in output from the first unit."
I assume that this could also increase the speed of a cooperative convoy of sailboats, that have a good reason to stay close. I wonder if the fleets of sailing ships of Admiral Nelson's time took advantage of this. A few extra ergs of force in a sea chase could make a large difference.
The idea here is 'stay out of dirty air better'. It isn't a real gain for the downwind turbines, just less of a loss.
This concept has long been known to sailors. And I presume that sailing in convoys took this effect of dirty air well into account.
You see this in competitive dinghy racing. One person will intentionally starve their competitor of good air, so they know and could do the opposite if they wanted.
Lots of sports deal with this “dirty air” concept like Formula 1 especially, regulations were changed for this season so the car in front produces cleaner air off the back so cars behind can follow better (which provides a better chance to overtake/better viewing spectacle).
The 1.2٪ figure was a month long average from a real-world test. In certain conditions they got 32% higher efficiency. Presumably those are the conditions when the wind is blowing sub-optimally.
Unrelatedly, from personal experience both onshore and offshore windfarms seem to be packed much tighter than in a line.
These rows are spaced far enough apart that I don't think the OP research would help as much. Even where they are clustered, they are at different elevations.
That was the point of the prior comment about seeing them strung out vs clustered. Obviously, location location location. West Texas wide open spaces means you can spread them out so they are not ideal candidates. I was just saying that rather than saying something anecdotally, you can make the claim with supporting evidence.
This made me try to imagine solutions to the no-wind condition, whether there is any control strategy that can work for it. And I laughed at the idea of one wind mill blowing at another to get a net gain of energy. But then I thought, is that really such an absurdity..?
What if.. what if you can expend energy to "suck in" a nearby storm for instance? I don't know how viable it would be, but at least it doesn't seem to obviously break physical laws.
I’d like to see stored hydro that was a little more environmentally friendly. Perhaps a series of floodgates where one area is mostly dry and another mostly wet, rather than everything being intermittently wet all year.
I get it. You want to store energy in man-made tornadoes, then discharge them slowly when wind calms down. So the optimal layout is circular. By adjusting the turbine, they can either feed into or pull out of the cyclone. Genius!
No wind all day is quite a bit different from spotty wind. Any day with a little wind slows your withdrawal rate.
And while you might not be able to decommission a peaker plant, one of the ways power gets around emissions limits is that the pollution is annualized. You can reduce the emissions of a plant by half of you can turn it off part of the year, so where possible they spin up the better plants first. Anything that keeps their next worse plant offline more helps the rest of us.
What about when the wind is tangent to installation line and blowing across them. Wouldn't they all rotate to face the wind and now be in front of one another?
I think placing them in a grid format, where each grid node gets a turbine. That way you'd have them aligned when the wind blows E<->W, S<->N, but also SW<->NE and SE<->NW even if they're x√2 away from each other in that case
The majority places have a strong directionality of wind due to the terrain, it's quite plausible that this place this happens very, very rarely (and the planners of that wind farm definitely took that into account).
E.g. the first random example of a wind rose plot I googled - https://www.researchgate.net/figure/Wind-rose-plots-of-all-N... - is quite typical, where winds almost all times go one way or the opposite way, and very rarely in the perpendicular direction.
Looks like they did some pretty comprehensive testing:
> "In a months-long experiment in a real utility-scale wind farm in India, the predictive model was first validated by testing a wide range of yaw orientation strategies, most of which were intentionally suboptimal. By testing many control strategies, including suboptimal ones, in both the real farm and the model, the researchers could identify the true optimal strategy. Importantly, the model was able to predict the farm power production and the optimal control strategy for most wind conditions tested, giving confidence that the predictions of the model would track the true optimal operational strategy for the farm. This enables the use of the model to design the optimal control strategies for new wind conditions and new wind farms without needing to perform fresh calculations from scratch."
There are definitely a number of installations where this could be useful. My favorite example is Antelope Valley in Southern CA, where the turbines stretch out as far as the eye can see. The scale is absurd. 3288 turbines are there, according to https://eros.usgs.gov/media-gallery/earthshot/wind
That's interesting from the satellite view, seeing the various installations next to each other and various approaches to layout. Some lined up tight, some spaced out, some perfectly straight lines, some meandering a bit.
I live in the Valley; we get some huge winds and gusts around here, especially along the north slopes. Once I repaired a blown-down wooden fence out in the county for the Nth time, "really" fixing it by bracing with a 2x4 from the top to the ground behind it. Came back a few weeks later and the wind had jacked the whole panel out of the ground, pivoting on the brace's grounded end, pulling up fence posts buried three feet deep.
It's already slatted. TBH, the fence has never been properly repaired, due to materials on hand and a certain impatient father-in-law. The posts should be buried 4 ft deep and bedded in a 3-or-4 inch wide concrete base. But going to check on the place and fixing the fence is kind of a ritual now, a good excuse to get out to the country. Beautiful wide-open tranquility.
- IIRC they actually need to be locked beyond some safe maximum windspeed because the forces they're under are indeed sufficient to tear them apart. I guess if local conditions can change faster than they can be locked (or if the locking systems can fail?) with any frequency, then such damage might be common.
- I do also wonder if something like a bird impact is common, and whether it's enough force to crack the fiberglass (or whether reverberations of the impact on an active turbine would cause trouble)?
Wind farms in my state have grids of towers across square miles. So nearly every tower is in the 'wind shadow' of any number of other towers. This seems like a very suitable innovation here.
Why are wind turbines constructed like reverse propellers?
Would they not be more efficient if they were shaped like an actual turbine with a deep spiraling blade, placed inside a cylindrical or conical encasing?
I believe that if you consider the money it takes to add the conical casing, and instead just make a bigger tri-blade without a casing with that same money, you come out ahead.
Not an expert, but that rings true. Probably environmental impact of a huge volume of air sucked into the cone and fed into a high-speed grinder should be factored in as well.
I'm sure both are true. It doesn't make physical sense or economic sense. Encasing the entire turbine with a shroud the diameter of the blades would be astronomically expensive.
However, there is no rule in physics that you can't 10x the windspeed with a focused inlet.
Natural mountain ranges around some farms have a similar effect to improve power output, but we would never consider building a natural mountain to improve turbine efficiency
> but we would never consider building a natural mountain to improve turbine efficiency
Maybe we could? Mining operations already produce huge volume of material from tailings and overburden. Not an outrageous idea to be more strategic in how and where that material is placed. Could create some artificial ranges with better wind properties.
This is a really good question. The reason regular turbines and wind turbines are designed differently is because regular turbines have a small volume of fluid experiencing a large change in pressure while wind turbines have a large volume of fluid experiencing a small change in pressure. You see the exact same thing in fans - big ceiling fans look like wind turbines and air compressors look a lot like regular turbines.
I’m sure the cost of a casing plays into it, but its primarily about the energy efficiency of different blade shapes in different hydraulic conditions.
I mean the whole point of the casing as I understand it is to contain a flow at above ambient pressure - not something that even makes sense for wind. You could have different (more turbine-like) blade geometry without a casing.
There's a bunch of maths around Betz' law that dictates how the efficiency works, but it turns out that the theoretically optimal structure is a single blade: http://www.wind-works.org/cms/index.php?id=543
For mechanical engineering reasons, mostly to do with evening out the load at the point of blade attachment, the industry has mostly converged on three.
Remember that the blades are aerofoils, effectively wings. They don't need to touch all the air in their swept area, their effect is given by redirecting the flow of the whole stream of air.
Casings are only useful for small turbines operating at high pressures, where the energy lost to spilling over the tip of the blade would be high.
For the same reason propellers aren't shaped like compressor blades inside a cylindrical encasing. The cylindrical encasing dramatically reduces air flow, but is necessary for large pressure changes. For a brayton cycle heat engine, like a jet engine, you need to maximize pressure gradient for optimal efficiency, but if you're not burning fuel then you want to minimize pressure gradient and maximize mass flow rate.
You've already received some good responses (particularly from /u/pjc50), but one particular point may not be real clear.
Generally speaking, the power a wind turbine can generated is proportional to the entire swept area. So, other things being equal, it is better to go for longer blades to increase the area, rather than trying to "capture all the wind" in a smaller cross-sectional area.
So the most efficient use of your wind turbine's mass (which is proportional to cost) is to make it as big as feasible.
Serious question here. Why I see all these breakthroughs coming from MIT? Are they really heads and shoulders above everyone else or do they have great PR/marketing?
Probably both, it is a top research university in the world, with a lot of smart people and funding. Also note the "T" in MIT stands for technology, they do tend to focus a bit more on practical applications and not just theoretical knowledge.
At least in this case, it seems that MIT is only tangentially related to the research. The lead researchers are from Spain and India with financing from Siemens.
Its good marketing and I would keep an eye on what accounts are submitting these. Its practically a trope on HN at this point. Not to say that MIT doesn't do cool stuff, but there are few institutions as good at self promotion.
If you look at the paper it's actually a collaboration between MIT researchers, Caltech researchers, a Spanish Siemens groups, and an Indian power company.
MIT just has a more effective marketing division, it seems. Here's the Caltech press release for comparison.
> "Collectively, wind farms generate about 380 billion kilowatt-hours each year in the United States. If every U.S. wind farm were to adopt the new strategy and see efficiency increases similar to those found in the new study, it would be equivalent to adding hundreds of new turbines capable of powering hundreds of thousands of homes to the nation's power grid, says Caltech's John O. Dabiri (MS '03, PhD '05), the Centennial Professor of Aeronautics and Mechanical Engineering, and senior author of a paper on the project that was published by the journal Nature Energy on August 11."
In addition to the other replies, it's also worth mentioning that they have an incredibly large endowment, worth $27.4 billion last year, the fifth largest of any private university in the US. That's compared to an average of $1.1 billion, and a median of just $200 million, less than 1% of MIT's.
There is really no excuse for the US to not provide every intelligent high school student the opportunity to enrol in MIT-quality education for free. And, for that matter, to enrol in high-quality trades programs, because we need people who can actually build, maintain, and repair, too.
Imagine the technical and infrastructure improvements. We would leap ahead by every metric.
This makes me wonder if it could be optimized further if mechanical design changes are explored. It's common practice in aerospace to minimize dirty air in certain cases. I wonder if there are opportunities where different turbine designs could be deployed depending on the windmill density.
> Virtually all wind turbines, which produce more than 5 percent of the world’s electricity, are controlled as if they were individual, free-standing units.
I refuse to believe this, every wind engineer would know one windmill affects the next.
Its not as clear as the picture either where they are lined up. In most locations wind changes direction so for some flows they'll interact different to others.
Wind engineers know this, but the software control work is non trivial and, apparently, simply hasn't been done.
A few years ago I was talking with a family member who is in wind power research. They were trying to convince me to start writing turbine control software because it is massively inefficient and naive.
I was shocked at some of the optimizations they are lacking.
Interesting development, but quite a few of these concerns are normally dealt with during wind park development and siting, taking care of the 'wake effect' in the prevailing wind with all machines operating is pretty much standard. The upside of this - if I understand it correctly - is that it will try to find another optimum when the wind is not from the 'ideal' direction that the park was originally designed for. So it will depend very much on how variable the winds are in a particular locality whether this will give an advantage.
I'm curious how it will play out in practice when they start using it on large offshore installations for instance.
Cool. We have worked with a customer on this exact thing and deployed an edge and cloud controller that orchestrates control changes based on the all the turbines. Such a great project!
79 comments
[ 3.6 ms ] story [ 133 ms ] threadLocal control, and no need for a global coordinator, might be so much simpler as to be worth losing some efficiency / not going into integration hell.
The utility might own wind turbines from different manufactures, but they are not in the same wind farm. I suppose there might be places where two wind farms border each other that you want different devices, but for the most part you can optimize each wind farm individually with no need to worry about manufactures.
Farms can have different makes and models. I also think that there is a lot of on board control.
Shipping is also rather expensive, so your are probably going with the nearest factory for everything. (each blade needs a semi with an oversize load permit, and "chase cars" both in front and behind with the right lights and signs)
Of course if a turbine fails in 5 years (I don't know what the warranty is, so I'm going to use 5 years) they might replace it with one from someone else, but that isn't common.
I don't know how much is onboard controls. However someone is feeding the weather instructions in, and when demand is low someone is telling a few to shut down. They also do remote monitoring for issues that maintenance needs to fix. That connection just needs an upgrade, along with some new software for the onboard controls and it can be done offboard. (this may not be easy, but compared to a turbine it is cheap)
At the extreme, I am familiar with farms that have been expanded over 25 years and have a huge variety of builds.
I am also aware of a number of farms that have at least 2 different sized turbines.
I'm reasonably sure that all wind turbines in my area come from Siemans. (they have a factory in my state, any other make would be shipped in from a considerable distance)
local maximizing presumably already deals with the effects from upstream turbines, global (also presumably) only adds consideration for downstream turbines
The real difficulty lies in:
1) Noise in the on-turbine wind speed and direction measurements and/or robustly (see point #2) operating LIDAR or met masts in front of the farm to try to avoid said measurement noise.
2) Actually arriving at a robust, operational in real-world conditions, fully closed-loop control system. A commercial wind farm has to operate 24/7 for 25 years without a bunch of engineers and scientists babysitting it, which is what is likely to end up happening if the cool control system relies on offline simulation results, topographical data, and/or human-supervised calibration & tuning.
It's not all doom and gloom: Ongoing improvements in sensor price/quality will probably make these kind of global control systems more and more practically feasible in the future.
1. You need to recognize the opportunities exist in the first place.
2. You need a global controller that can aggregate and optimize for a global solution (and the global solution might not necessarily simply to maximize the aggregate throughput, but there might be other factors into account), which may involve some algorithmic design (in some cases, you need to design new algorithms).
3. You need to justify that global controller gives you a superior solution compared to locally greedy solution. As in this article, a global solution gives you about 3% improvement compared to the local controller, and the local controller algorithm is substantially easier to write.
Background: in my previous job at Meta, I wrote such a global control algorithm for controlling the rate of data going in and out each data center. It involved some really interesting algorithmic design.
Even if you have a perfect implementation of this, and you don't need to deploy new networks, etc, and you put in a lot of NRE to make this easy deploy... how much engineering effort is still needed to start squeezing 1-2% out of a wind farm?
The research was definitely worth pursing. A 1.2% overall efficiency gain is not nothing, and is indeed significant enough that I think people will want to implement it.
On the other hand, without doing some extensive research, it wasn't clear what the magnitude of the improvement actually was.
I assume that this could also increase the speed of a cooperative convoy of sailboats, that have a good reason to stay close. I wonder if the fleets of sailing ships of Admiral Nelson's time took advantage of this. A few extra ergs of force in a sea chase could make a large difference.
Often, wind turbines are arranged in a line across the usual wind front, so turbulence isn't typically an issue.
So, in this case, when wind passes over multiple nearby turbines serially, then there is a 1.2% gain on efficiency.
Still a worthwhile deployment if the model is accurate. Needs to be tested.
Unrelatedly, from personal experience both onshore and offshore windfarms seem to be packed much tighter than in a line.
But out west, some (not all) of them are placed along ridgetops in a wide line, with none behind each other.
https://www.google.com/maps/search/wind+farm/@32.3343137,-10...
You can only store so much power for interday variations. Everything beyond that takes fossil fuels.
What if.. what if you can expend energy to "suck in" a nearby storm for instance? I don't know how viable it would be, but at least it doesn't seem to obviously break physical laws.
I’d like to see stored hydro that was a little more environmentally friendly. Perhaps a series of floodgates where one area is mostly dry and another mostly wet, rather than everything being intermittently wet all year.
And while you might not be able to decommission a peaker plant, one of the ways power gets around emissions limits is that the pollution is annualized. You can reduce the emissions of a plant by half of you can turn it off part of the year, so where possible they spin up the better plants first. Anything that keeps their next worse plant offline more helps the rest of us.
E.g. the first random example of a wind rose plot I googled - https://www.researchgate.net/figure/Wind-rose-plots-of-all-N... - is quite typical, where winds almost all times go one way or the opposite way, and very rarely in the perpendicular direction.
> "In a months-long experiment in a real utility-scale wind farm in India, the predictive model was first validated by testing a wide range of yaw orientation strategies, most of which were intentionally suboptimal. By testing many control strategies, including suboptimal ones, in both the real farm and the model, the researchers could identify the true optimal strategy. Importantly, the model was able to predict the farm power production and the optimal control strategy for most wind conditions tested, giving confidence that the predictions of the model would track the true optimal operational strategy for the farm. This enables the use of the model to design the optimal control strategies for new wind conditions and new wind farms without needing to perform fresh calculations from scratch."
Streetview: https://www.google.com/maps/@35.0385954,-118.2567896,3a,75y,...
One example, but it's easy to find more... https://www.google.com/maps/@35.0727844,-118.2627452,139m/da...
Are they really so fragile? It looks like maybe 2-3% of them have fallen apart.
- I think they are fiberglass
- IIRC they actually need to be locked beyond some safe maximum windspeed because the forces they're under are indeed sufficient to tear them apart. I guess if local conditions can change faster than they can be locked (or if the locking systems can fail?) with any frequency, then such damage might be common.
- I do also wonder if something like a bird impact is common, and whether it's enough force to crack the fiberglass (or whether reverberations of the impact on an active turbine would cause trouble)?
Would they not be more efficient if they were shaped like an actual turbine with a deep spiraling blade, placed inside a cylindrical or conical encasing?
However, there is no rule in physics that you can't 10x the windspeed with a focused inlet.
Natural mountain ranges around some farms have a similar effect to improve power output, but we would never consider building a natural mountain to improve turbine efficiency
Maybe we could? Mining operations already produce huge volume of material from tailings and overburden. Not an outrageous idea to be more strategic in how and where that material is placed. Could create some artificial ranges with better wind properties.
I’m sure the cost of a casing plays into it, but its primarily about the energy efficiency of different blade shapes in different hydraulic conditions.
For mechanical engineering reasons, mostly to do with evening out the load at the point of blade attachment, the industry has mostly converged on three.
This is also linked to tip speed ratio: http://www.reuk.co.uk/wordpress/wind/wind-turbine-tip-speed-... ; the tip speed is usually several times faster than the wind speed.
Remember that the blades are aerofoils, effectively wings. They don't need to touch all the air in their swept area, their effect is given by redirecting the flow of the whole stream of air.
Casings are only useful for small turbines operating at high pressures, where the energy lost to spilling over the tip of the blade would be high.
In Betz's own derivation, the ideal rotor is an "actuator disk", having an infinite number of blades, which have no drag.
Generally speaking, the power a wind turbine can generated is proportional to the entire swept area. So, other things being equal, it is better to go for longer blades to increase the area, rather than trying to "capture all the wind" in a smaller cross-sectional area.
So the most efficient use of your wind turbine's mass (which is proportional to cost) is to make it as big as feasible.
MIT just has a more effective marketing division, it seems. Here's the Caltech press release for comparison.
https://www.caltech.edu/about/news/tweaking-turbine-angles-s...
> "Collectively, wind farms generate about 380 billion kilowatt-hours each year in the United States. If every U.S. wind farm were to adopt the new strategy and see efficiency increases similar to those found in the new study, it would be equivalent to adding hundreds of new turbines capable of powering hundreds of thousands of homes to the nation's power grid, says Caltech's John O. Dabiri (MS '03, PhD '05), the Centennial Professor of Aeronautics and Mechanical Engineering, and senior author of a paper on the project that was published by the journal Nature Energy on August 11."
Source: https://www.insidehighered.com/news/2022/02/18/college-endow...
Imagine the technical and infrastructure improvements. We would leap ahead by every metric.
I refuse to believe this, every wind engineer would know one windmill affects the next.
Its not as clear as the picture either where they are lined up. In most locations wind changes direction so for some flows they'll interact different to others.
A few years ago I was talking with a family member who is in wind power research. They were trying to convince me to start writing turbine control software because it is massively inefficient and naive.
I was shocked at some of the optimizations they are lacking.
I'm curious how it will play out in practice when they start using it on large offshore installations for instance.
It has been standard practice in most industries to co-opt any improvement into increasing the company’s stickiness.
It would be a shame if it did.