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Alistair_Heaton
Mechanical
That's a lot of capacity that's been lost. Must admit being Aberdonian we always associate Texas with hot and humid... Not snow storms.
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Texas power issues. Windfarms getting iced up. 67
- Thread starter Alistair_Heaton
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If all 200 million US cars were electric cars and were connected to the grid 75% of the time,then it might be possible to use their batteries as a sort of backup. A more realistic approach would be to modify the homeowner's load center and EV recharger to allow the car's battery to power the home's light duty circuits ( overhead lights, alarms, modems,furnace fan, and refrigerator) via the car battery during times of electrical outages. The optimum EV recharging period would normnally be during daylight hours while the EV is parked at work , so as to take advantage of the peak solar PV output to the grid; this would reduce the need for reserve power generation capacity and reduce the need to cycle thermal stations twice a day.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
electricpete
Electrical
I was waiting for someone to answer this since I'm sure there are folks here that know a heckuva lot more than me about wind turbines. But since I didn't see any answer, here was my thoughts fwiw:itsmoked said:
I think if you rotate the blade closer to perpendicular to the wind then it presents more area to the wind and there is too much wind loading force (and stress) on the blade itself. If you rotate the trailing edge further away from the wind then there is increased torque pushing towards overspeed even with full generator output. So above a certain windspeed there's nowhere to adjust the blades where you can keep both the blade wind-loading force and the speed within bounds. At that point you need to use a brake to lock from rotation and turn the blades further away from the wind to present minimum area.
disclaimer: that's a lot of speculation, I may be way off base.
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(2B)+(2B)' ?
- Thread starter
- #383
Alistair_Heaton
Mechanical
There is also something to do with the force required to alter the pitch of the blade.
This was my bible about propellers
This was my bible about propellers
JohnRBaker
Mechanical
When we first moved to California in 1980 and we made a trip out to Palm Springs, it was the first time we'd ever seen a really large wind generation facility (and it was nothing compared to now). Note that I had seen examples of early so-called Danish windmills (i.e. wind turbines), with the classic three-blade design, but only a few at a time.
With respect to two-bladed wind turbines, that was something that we noticed when we were driving out to Palm Springs, that a lot of the wind turbines were only two-bladed and yes, they moved much faster than the three-bladed ones. Of course, as the larger three-bladed units were being installed, it seemed like the two-bladed ones were the first to be taken down to make room for the significantly larger new wind turbines, which of course were all three-bladed.
Here are some photos I took of some wind turbines which NASA was conducting experiments with. Now I'm not sure how long they had been there as we had seen the signs on the road indicating that the experimental site was there but had never stopped to take pictures until one of our later visits to the area, that is Southeastern Washington state, near Goldendale, just a few miles North of the Columbia River:
August 1984 (Minolta XG-M)
August 1984 (Minolta XG-M)
Notice how this two-bladed wind turbine used 'flaps' to, I assume, limit the speed of the turbine.
August 1984 (Minolta XG-M)
As for Palm Springs, for anyone who's never been out there, here's shot of just a small section of the wind farm, as seen from the top of Palm Springs Aerial Tramway at Mount San Jacinto State Park:
February 2016 (Sony a6000)
And, yes, those blades are very large. During our various travels across the country we've seen them being trucked (our course if you saw one, there would be at least another two further up the highway) to their installation site, like below near Salina, Kansas:
August 2017 (Sony a6000)
August 2017 (Sony a6000)
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
With respect to two-bladed wind turbines, that was something that we noticed when we were driving out to Palm Springs, that a lot of the wind turbines were only two-bladed and yes, they moved much faster than the three-bladed ones. Of course, as the larger three-bladed units were being installed, it seemed like the two-bladed ones were the first to be taken down to make room for the significantly larger new wind turbines, which of course were all three-bladed.
Here are some photos I took of some wind turbines which NASA was conducting experiments with. Now I'm not sure how long they had been there as we had seen the signs on the road indicating that the experimental site was there but had never stopped to take pictures until one of our later visits to the area, that is Southeastern Washington state, near Goldendale, just a few miles North of the Columbia River:
August 1984 (Minolta XG-M)
August 1984 (Minolta XG-M)
Notice how this two-bladed wind turbine used 'flaps' to, I assume, limit the speed of the turbine.
August 1984 (Minolta XG-M)
As for Palm Springs, for anyone who's never been out there, here's shot of just a small section of the wind farm, as seen from the top of Palm Springs Aerial Tramway at Mount San Jacinto State Park:
February 2016 (Sony a6000)
And, yes, those blades are very large. During our various travels across the country we've seen them being trucked (our course if you saw one, there would be at least another two further up the highway) to their installation site, like below near Salina, Kansas:
August 2017 (Sony a6000)
August 2017 (Sony a6000)
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
There was something said about having very little hydroelectric in Texas, and this is true, but one hydroelectric source is on lake Texhoma (not sure about the spelling), near Denison Texas, which is on the border between Texas and Oklahoma. This is a federal dam, as it is on the border.
However, it may have been limited by the lake level, as part of it's function is to limit flood waters.
Before tripping generators on underfrequency, I believe most plans (as mandated by NERC), trip off load prior to tripping generators. This is true on both the eastern and western grids.
Feathering of wind generators is possible, but at what point will they not be able to feather because the wind is too high?
A minor point, don't use car batteries for energy storage. Car batteries are for a short duration of energy to start a car. Storage batteries have thicker plates that can be deeper cycled to hold energy. Car batteries have thin plates with more surface area to be able to make a fast jolt of energy. Sort of like the difference in a sprinter, and a jogger. The sprinter wins a short race, but the jogger wins the long race.
Have you noticed that golf cart batteries are about the same size as a car battery? But the golf cart battery is only 6 volts, where a car battery is 12 volts.
However, it may have been limited by the lake level, as part of it's function is to limit flood waters.
Before tripping generators on underfrequency, I believe most plans (as mandated by NERC), trip off load prior to tripping generators. This is true on both the eastern and western grids.
Feathering of wind generators is possible, but at what point will they not be able to feather because the wind is too high?
A minor point, don't use car batteries for energy storage. Car batteries are for a short duration of energy to start a car. Storage batteries have thicker plates that can be deeper cycled to hold energy. Car batteries have thin plates with more surface area to be able to make a fast jolt of energy. Sort of like the difference in a sprinter, and a jogger. The sprinter wins a short race, but the jogger wins the long race.
Have you noticed that golf cart batteries are about the same size as a car battery? But the golf cart battery is only 6 volts, where a car battery is 12 volts.
EdStainless
Materials
We shipped 3.8m ft of tubing to a power plant that required 115' straight lengths. We could do it because trailers that long exist for hauling WT blades.
At one time they were talking about putting the wind farms on their own sub-grid (like the large hydro plants). That way the average power available would only change very slowly. But no one wanted to pay for the system.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
At one time they were talking about putting the wind farms on their own sub-grid (like the large hydro plants). That way the average power available would only change very slowly. But no one wanted to pay for the system.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
Fischstabchen
Electrical
The blade count is based on manufacturing cost. More blades recover more energy from the wind but it isn't linear and becomes very incremental past 3 blades while adding more and more weight that needs to be supported. There isn't a "right" design but just designs with better returns or quicker paybacks.
cranky108, Texoma, you were close. That is a big, beautiful lake, I camp there off and on. All the lakes in the region are always trying to strike a balance among recreation, flood control and generation (if present). Somebody is always mad at the Corps 
The die-hard "dry" campers swap two golf cart batteries for one regular 12V for longer life, by what I read. Some of these people are fanatical about battery management, charge profiles, times, etc. I'm not one of 'em. Most times when I camp AC is involved
The problem with sloppy work is that the supply FAR EXCEEDS the demand
The die-hard "dry" campers swap two golf cart batteries for one regular 12V for longer life, by what I read. Some of these people are fanatical about battery management, charge profiles, times, etc. I'm not one of 'em. Most times when I camp AC is involved
The problem with sloppy work is that the supply FAR EXCEEDS the demand
Alistairs propeller bible..
Hmmm .. hmmmm ...![[ponder]](/data/assets/smilies/ponder.gif "[ponder] [ponder]")
okay.. ... sorry ..
Constant speed propellers for dummies ;-)
I know a constant speed propeller isn't the same as a WG;ers but in my mind it's a bit like the reversed function so there has to be some similarities in mechanical function.
![[idea]](/data/assets/smilies/idea.gif "[idea] [idea]")
Now I see why I don't get it, WG:s have asynchronous generator, which means that they requires a slip value of about 3% over synchronous speed, all the time to produce power.
So they need to have a blade angel that makes the rotational speed the same regardless of how much it blows.
In my mind it has always been a brushless DC generator or something like that, that produces power all the time regardless of windspeed or blade rpm.
But with a asynchronous generator you need to keep the rotational speed in a specific speed window otherwise it won't generate any power.
So it is both limited by the generator and the mechanics.
A brushless DC generator would more or less only be limited by the the mechanics.
Best Regards A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
Hmmm .. hmmmm ...
okay.. ... sorry ..Constant speed propellers for dummies ;-)
I know a constant speed propeller isn't the same as a WG;ers but in my mind it's a bit like the reversed function so there has to be some similarities in mechanical function.
Now I see why I don't get it, WG:s have asynchronous generator, which means that they requires a slip value of about 3% over synchronous speed, all the time to produce power.So they need to have a blade angel that makes the rotational speed the same regardless of how much it blows.
In my mind it has always been a brushless DC generator or something like that, that produces power all the time regardless of windspeed or blade rpm.
But with a asynchronous generator you need to keep the rotational speed in a specific speed window otherwise it won't generate any power.
So it is both limited by the generator and the mechanics.
A brushless DC generator would more or less only be limited by the the mechanics.
Best Regards A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
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1
- Moderator
- #392
Anna;
You asked about the time to ramp up and down on a hydro plant.
The limit is the inertia of the moving water in the penstocks.
Depending on the size and length, there may be hundreds of tons to thousands of tons of moving water in the penstock.
Greater output demands higher flow which means the water must be accelerated.
Ramping down too rapidly can and has been catastrophic.
The largest hydro-electric plant in Russia.
August 2009;
This was initially reported as a transfoormer explosion.
When more information became available, it was disclosed that the gates had been closed too quickly.
The resulting water hammer broke a penstock.
The flood of water destroyed at least one generator.
Then the transformer exploded.
Scroll down for more pictures
Eng-Tips discussion
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
You asked about the time to ramp up and down on a hydro plant.
The limit is the inertia of the moving water in the penstocks.
Depending on the size and length, there may be hundreds of tons to thousands of tons of moving water in the penstock.
Greater output demands higher flow which means the water must be accelerated.
Ramping down too rapidly can and has been catastrophic.
The largest hydro-electric plant in Russia.
August 2009;
This was initially reported as a transfoormer explosion.
When more information became available, it was disclosed that the gates had been closed too quickly.
The resulting water hammer broke a penstock.
The flood of water destroyed at least one generator.
Then the transformer exploded.
Scroll down for more pictures
Eng-Tips discussion
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
I ESD'd a 24" oil pipeline flowing 200,000 bbl/day once. Pressure went from 300 psig to 1750 in a few minutes. Relief valves opened there and filled a 10kbbl standby tank with 9.5kbbls. It was not something I'd want to do again. A lot like a 4.1 earthquake, but with more noise.
- Moderator
- #395
For a perfectly rigid pipe: As the time to stop the flow approaches zero, the pressure approaches infinity.
That never happens though.
The pipe breaks first.
The hydraulic ram pump works on the water hammer principle.
A 5 foot head of running water may be used to pump water to heads of over 100 feet.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
That never happens though.
The pipe breaks first.
The hydraulic ram pump works on the water hammer principle.
A 5 foot head of running water may be used to pump water to heads of over 100 feet.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
I live less then 15 km from the largest hydro power plant in Sweden Stornorrfors
But I think it has a different construction than the Russian one I have only been inside there ones when I was going in school.
Our hydro plant's are old so we have mostly long water systems (350 km of waterway) as "buffert" at least for Stornorrfors , since the fall height isn't so great.
Norway have short waterways but much higher mountains.
I am not shore if we have any hydro storages at all.
Not the way it's done in other places (with one high pond and one low one ) pumping water up, falling down.
And thanks waross for explaining your problem solution with frozen water valves
But I knew what a rumpus room was !
I seen to many English/American house makeover program.. ;-)
Best Regards A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
But I think it has a different construction than the Russian one I have only been inside there ones when I was going in school.
Our hydro plant's are old so we have mostly long water systems (350 km of waterway) as "buffert" at least for Stornorrfors , since the fall height isn't so great.
Norway have short waterways but much higher mountains.
I am not shore if we have any hydro storages at all.
Not the way it's done in other places (with one high pond and one low one ) pumping water up, falling down.
And thanks waross for explaining your problem solution with frozen water valves
But I knew what a rumpus room was !
I seen to many English/American house makeover program.. ;-)
Best Regards A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
LittleInch
Petroleum
That's only 2m/sec BI. How fast did it close?
Must have been something other than surge?
But yes, you can get very high pressures if you stop a moving pipeline too fast
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Must have been something other than surge?
But yes, you can get very high pressures if you stop a moving pipeline too fast
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I thought the smaller the propeller the faster it can spin. (drones 20,000rpm)
You could switch for instance from a 10 foot two bladed prop to an 8 foot 3 bladed to a 7 foot four bladed to a 6 foot 5 bladed and in each case turn it faster if desired. That due to less tip speed and less centrifugal forces. Isn't that the reason some of the WWII fighters had scads of blades.
Keith Cress
kcress -
You could switch for instance from a 10 foot two bladed prop to an 8 foot 3 bladed to a 7 foot four bladed to a 6 foot 5 bladed and in each case turn it faster if desired. That due to less tip speed and less centrifugal forces. Isn't that the reason some of the WWII fighters had scads of blades.
Keith Cress
kcress -
Well that was, what I was after if you want wind power that works when it really is storming, then shorter blades and higher speed would be better.
But if a asynkron generator needs to move with almost the same speed all the time independent of how much it is blowing then it want help.
It does not feel efficient.
I hope I am wrong ;-)
BR A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
But if a asynkron generator needs to move with almost the same speed all the time independent of how much it is blowing then it want help.
It does not feel efficient.
I hope I am wrong ;-)
BR A
“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
I just knew you'd ask about that. Turned out that somebody closed the valve on the tanker first. That spiked me at the meter station with around 800 psi. I figured that wasn't good, whatever it was, so I closed off and told the 4 pump stations to shut down too. All those transients, must have been a bunch of column separations, plus around a thousand meters of head coming down the last mountain range made for a rough ride. It sware it was 30m before things finally got quiet again. They had just repaired the relief tank, someone put the vacuum breaker in upside down and draining the hydrotest water collapsed the top at the rim and when they left that evening, after 3 days cleaning the tank spic and span, they told me not to get the tank dirty. They were going to do the final inspection in the morning. That got delayed.
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