Power Electronics Help to Control Electrical Grids 292
An anonymous reader writes: "IEEE Spectrum magazine has a timely article about how power electronics are proving necessary for the widespread connection of wind turbines to the electric power grid. It explains many issues that currently make it difficult to utilize wind power. Older articles discuss other issues affecting the nation's power grid."
Re:Control is the key... (Score:5, Informative)
The power company doesn't get an early warning for how much power people are going to use. They can guess based on weather conditions and history, but that's not accurate enough a number for them to work with.
Remember back to physics class... (or read this on How Stuff Works if you can't... [howstuffworks.com]). Voltage equals current times resistance. And anything that you plug in to use power is a resistor. What this means in simple terms is that whenever you turn on anything, you've changed the resistance value on your local power network, so either you've just changed the voltage on the power network, or some power generator somewhere is going to have to step up to the plate and provide more current.
If you've ever read APC marketing material, you know that you want your computer, and for that matter everything else you plug in, to get a nice steady dose of 120 Volt power. There's a little room for tolerance, but not much.
So, whenever a city's power draw changes, the electicial system's gotta react pretty quickly. Too little voltage is a clear problem, it's a brownout. Too much voltage is also a problem, it's a power surge. The large power grids come into play as a way for a network that has too much power and a network that has too little to solve each others problems by joining together and letting physics do its thing.
So, when something goes horribly wrong, it takes nine seconds for a ordinary day to become a bad one. Nobody had any warning because the power grid has to react instantly to unexpected situations, and usually does just fine. It was the one time it didn't react properly that we all noticed.
rock the vote (Score:3, Informative)
For those unaware of what's going on, here is a quick excerpt of President Bush denying money for a secure grid... (Source [politrix.org])
On top of this it was announced that grids would be targeted by terrorists.
(source [theage.com.au])Here is a link to a mirrored doc of the Electronic Power Risk Assessment [politrix.org], there is going to be a huge amount of finger pointing, and political partisan bs behind this entire incident, but read it for yourself in plain english how your (P)Resident will not fund plan for a more secure system.
Off topic? I think not
Re:WTF (Score:2, Informative)
Doesn't quite ring true (Score:5, Informative)
While it's true that most wind turbines use induction generators, they do so for several reasons, including:
All the turbines I have worked with have either had modest capacitor banks to correct for reactive power, or used insanely cool AC/AC back-to-back inverters to produce line quality AC.
I'm also concerned about the article's allegations of power intermittence. Wind turbine rotors have a fair amount of rotational inertia, so they're not capable of passing every flutter of the wind to the generator. It seems that this part of the article is a sales pitch for a new product that the vast majority of installations won't need.
I was also amused at the requirement of wind turbines to "ride through" grid frequency variations. This is basically a nice way of spinning the fact that wind turbine controllers are often far more picky about the frequency they'll accept or put out, than the rather poor regulation that applies to our power grids.
An finally, that picture. Where on earth did they get it? Apart from the fact that it's a contravention of every safety code to climb the tower of a running turbine, the climber must be a human sloth. To get that kind of motion blur on wind turbine blades, you'd have to have several minutes' exposure. Thus our perfectly sharp climber (and their horse) must be moving incredibly slowly ...
Re:Switch to DC (Score:4, Informative)
I do not remember the figures, but this is the reason why AC was chosen for power distribution, even though there were various factions hyping the danger of using AC (electrocution and such).
Also this is why AC is transmitted at such high voltages for the large runs... for the same amount of power, a higher voltage means less current, less current means less voltage drop across the line, therefore less loss of power...
Re:One of the issues that stops wind power. (Score:2, Informative)
Another great way of countering the problem is... go ahead and build it anyway. Most (non-Danish, Dutch or German) people haven't seen a wind turbine, and they're usually pleasantly surprised about how unobtrusive they are.
Wind is only part of the answer. (Score:5, Informative)
While the *idea* of wind power is certainly a nice one, and the notion of helping the environmement is well intentioned, the reality is that wind is insufficient as a power source and as a result - it's ability to displace the most polluting source, coal, will be ineffective. Other solutions will be required to truly solve the pollution/capacity problem that we face.
A potentially viable start to "solving" some fo these problems would be to distribute residential power generation, especially in dense urban areas. Technologies such as fuel cells, and compact turbines could be used for this. An added benefit of this strategy would be zero emissions and heat reclemation in the case of fuel cells, and better regulatory control over the emissions of compact gas fired turbines.
My two cents.
Re:home use?? (Score:2, Informative)
Re:Nice to see our patent system working (Score:3, Informative)
Re:Control is the key... (Score:1, Informative)
Amusingly, there was a nasty brownout here in winnipeg recently. Most of my systems are on UPSes, but my powermac in particular isn't.
So the brownout comes: a good half second of blackness followed by about 30 minutes of 50-80v on the lines (I was watching it with a voltmeter).
My UPSes are squealing away, running on batteries. I expect my powermac to be either crashed, off, or rebooting, but... nope, it's still working just fine, running on half the normal wall voltage.
No word of lie, the system didn't fail in any way through the entire outage. So much for computers being ultra-sensitive about power.
For the record, I also used to have a PC that could do this. Big 'ol full-AT brute with a 300w powersupply bigger than a whole shuttle Mini-PC. They sure don't make 'em like they used to. (and they certainly didn't when they made my ethernet switch - it's powersupply blew up during the same browout)
MSBLAST initiated Power Fallout ? (Score:3, Informative)
http://www.cnn.com/2003/US/08/16/blackout.chron.ap /index.html [cnn.com]
The timely coincidence between MSBLAST and power blackout is certainly _there_.
http://www.securityfocus.com/archive/1/333505/2003 -08-13/2003-08-19/0 [securityfocus.com] 3 -08-13/2003-08-19/0 [securityfocus.com] . php [automationtechies.com]
http://www.securityfocus.com/archive/1/333513/200
http://www.automationtechies.com/sitepages/pid641
http://www.pbs.org/wgbh/pages/frontline/shows/cybe rwar/view/ [pbs.org]
aspecially watch video #4. Just after 911 a cyber terroristic attack againts the powergrid was warned for by Gen. Clark from the Pentagon and other cyber security officials.
Robert
Re:fuel cell-Got gas? (Score:1, Informative)
And yet people manage [tokyo-gas.co.jp]
I suspect they do it more because they already have the infrastructure for oil (which is making money for them now), than it being technologicaly difficult. After all gas can flow down a pipeline just as readily as oil. The main difference is the liquification plant, and the ships.
Re:Management *is* key... (Score:3, Informative)
Anywhere in the continental shield would work, as long as you seal your bore-holes up with clay to prevent seepage. The shield has been stable for about 3 billion years.
go back to physics class (Score:1, Informative)
While this would be true if the power grid were wired in series, it is in fact wired in parallel [sinclair.edu], and although available current decreases when loads are added, the voltage remains constant.
Distrubuted electric balancing (Score:5, Informative)
Re:Nice to see our patent system working (Score:2, Informative)
<paranoid rant>
You see, GE could give a shit about wind power. All you have to do is follow the money. First of all check out the Energy Policy Act of 2003 [loc.gov], as Senator Domenici (NM) promises [energymarketers.com] it will fix a whole laundry list of problems with our energy supply (real and percieved). Do` we really need a new Under Secretary position for energy and science as well as two new Assistant Secretary positions: one for science and one for nuclear energy, I digress.
Anways Being from New Mexico, the home of Los Alamos National Laboratory [lanl.gov] and Sandia National Laboratories [sandia.gov] Don't be so shocked when Domenici's bill is pro nuclear.
Well, John Rice [ge.com] President and CEO GE Power Systems, recently (May 8) sez [lycos.com] he's cautiously optimistic that there will be a new nuclear facility in the United States and has spoken with half-dozen major nuclear utilities about building a new reactor .
And I suppose since GE is a member of United States Energy Association [usea.org] and gave about $9 Million [opensecrets.org] in campaign contributions (since 1990), It probably has some say into Domenici's Energy Bill which provisions for up to 8-10 new [nirs.org] 1100MW nuclear reactors that The taxpayers (read you and I) would pay, through loans, 50% of the costs to build these. And according to the Congressional Budget Office [cbo.gov] the risk of default on such a loan guarantee to be very high - well above 50 percent(p.11). The CBO also figures that each of these will cost somewhere in the neighborhood of $3Billion.
< /paranoid rant >
So why the hell would GE develop it's patents on Wind Turbines when the Good Ol US of A is gonna spend $52.6Billion [cbo.gov] over the next 10 years (p.1) on the Energy Policy Act of 2003.
Just follow the money....
Re:use surplus electricity for electrolysis (Score:5, Informative)
It's safer and simpler to pump water uphill into reservoirs to be extracted hydroelectrically later. That's what they do currently. earth-fill gravity dams are much cheaper and more reliable than massive electrolysis plants.
Storing Excess Capacity (Score:5, Informative)
Re:go back to physics class (Score:1, Informative)
Re:Management *is* key... (Score:1, Informative)
Tell that to people from the Ukraine. Ok, so that one was low. But the waste disposal problem is definitly not solved for nuclear power, storing (safely storing!) highly toxic and radioactive waste for millenia (Whilst our civilization is what, 10 000 years old?) is a non-trivial problem to say the least. Yeah I know that fuel can be recycled, but in practice it isn't. In Holland our 'recycled' fuelrods are just stacked up somewhere whilst the 'recycling' only contaminates more material and extracts weapons grade plutonium. The fuel can be "burned" and changed into shortliving isotopes - I'll believe it when I see it. (The research program was killed of, which I don't necesarily agree with.)
I concurr with you that renewables are not able to power everything everywhere - especially cities - with local power. But i also know that in Holland there are (expensive and subsidized, but give the tech some time) houses which are energy neutral over a year - they generate as much power as they use. I bet that a good part of your American (oops I'm assuming you are from the US, but the point still stands) suburbs could be powered the same way.
Ofcourse I haven't even touched on power conservation, which is certainly a real possibility in the United States. All I am saying is that with some creativity a lot can be done without having to go the all out nuclear route, at least a significant part of our energy use can be covered with renewables. And yes I vote green (groenlinks) in Holland
The key is nuclear power. (Score:2, Informative)
First the number of nuclear plants in the United States is somewhat over one hundered not one thousand.
The nuclear industry in this country is in terrible financial shape, because even with generous government subsidies it is hugely uneconomical. Nuclear power happens to be a very expensive way to boil water. You may be aware that nuclear power creates something called "nuclear waste". The government has provided the largest subsidy to the nuclear industry by promising to dispose of this waste at government (read taxpayer) expense. Fifty years into the history we still do not have a open repository for high - level civilian nuclear waste. (I believe that a military repository in Carlsbad, New Mexico is open or will open soon.) This nuclear waste has some unfortunate properties, such as extreme toxicity and long-term persistance (thousands of years). Releases radiation (the kind from breaches of reactor containment and waste storage systems, not the venting of mildly radioactive gas that are a part of normal plant operation) can cause widespread health effects. The problem here is that continued use of nuclear power creates additional waste, piling up for thousands of years - all to boil some water. (Another subsidy is the services that the government provides to the nuclear industry in the forms of security and regulation.) Nuclear power currently provides 14% of the electric power in the United States.
As far as your comments about wind, solar and water go, I'll address them one at a time.
* Water - Hydroelectric power is currently providing about 12% of the electric power in the US, though there is little room for growth, due to opposition to new dams.
* Wind - Did you read the article? There are hopes that wind will provide up to 20% of US power. This may be a bit optimistic, but the interesting part is that wind power went from being from an eco-hippie dream in the 1970's to a serious business in the present - without government subsidy. (Note to bird-lovers the newest wind turbines are large enough that the blades spin slowly and harm very few birds.)
* Solar - Applications of solar power are booming as cost and efficiency of photovoltaic cells improve. In many cases it is cheaper to use solar than to connect to the grid, such as temporary highway signs and homes more than 0.25 mile (0.4 km) from the electric grid. It is, however unlikely to ever be a significant percentage of electric power in the US.
The gigantic oil reserves that the poster refers to may the the Alaska National Wildlife Refuge, which has enough capacity to supply the US for 180 days. The percentage of domestically produced oil here is around 50% and has been falling for years and is porjected to continue to do so regardless of what the government chooses to do.
There was one source that is important that was not mentioned in the article or your post - conservation. This does not mean self-deprivation. It does mean higher standards in efficiency for all sorts of devives like the computer monitor you are currently staring at. It turns out that there's lots of savings to be had here and the additional cost to the consumer are greatly exceeded by the savings over the appliance life. The important point here is that we may not need to increase the amount of power generated to imporve standard of living (in the developed nations - developing world is a differnt case) even with moderate population growth.
Coal's technology has improved 300% from the 1970's with great advances in efficiency and emmission controls (scrubbers). Coal's tragic flaw it its C02 emissions. Unless someone figures how to capture and store the CO2(sequestration) then it will continue to be a problem if you are concerned about the greenhouse effect.
I have to agree with the poster's comments on the hydrogen economy. I just don't understand where the power is supposed to come from.
-Jon