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United States Technology

Power Electronics Help to Control Electrical Grids 292

Posted by michael from the dust-off-physics-101-knowledge dept.
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."
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Power Electronics Help to Control Electrical Grids More

Power Electronics Help to Control Electrical Grids

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  • Control is the key... (Score:5, Interesting)

    by The Eye of the Behol ( 678699 ) on Sunday August 17, 2003 @08:20PM (#6719711) Journal
    Maybe what we need is more control over the power, we need better systems and routines to warn us before something goes wrong. Not after.

    • Re:Control is the key... (Score:5, Informative)

      by LostCluster ( 625375 ) on Sunday August 17, 2003 @09:01PM (#6719900)
      Better warning systems... Wanna fill out forms telling the government exactly when you plan on turning on your lights?

      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.

      • Re:Control is the key... (Score:5, Insightful)

        by Edmund Blackadder ( 559735 ) on Sunday August 17, 2003 @09:41PM (#6720060)
        The power companies know very well how much power will be used. They have the necessary statistical data. When all the power use of tens of millions of people is added up, it fits very well into statistical predictions. So nobody is going to need to fill out any forms.

        Of course something unusual could happen, and the power companies have to be able to deal with that as well.

        But nothing unusual (as far as consumption)happened thursday afternoon. They just did not have their shit together.

        So it is completely reasonable to demand that the system be improved. I know it is all very complicated stuff, but i also know that problems like this can and should be prevented.
    • Maybe you are right. Here is an article about a recent developement that allows precise control over power transmission: http://www.sciencedaily.com/releases/2003/08/0308 1 5074303.htm [sciencedaily.com]

      A quote: The increasing frequency of electricity outages and outage duration are due primarily to lack of quick voltage support, leading to voltage collapse in many regions of the country and poor quality of power...
      The ETO can switch in less than 5us and carry up to 10kA. When closed it blocks up to 6kV

  • Ha (Score:5, Insightful)

    by pokka ( 557695 ) on Sunday August 17, 2003 @08:20PM (#6719713)
    A little ironic that this article on a world wide power grid was published in the September issue of Wired.

    IEEE Spectrum magazine has a timely article

    It's kind of funny how articles about the power grid appear in magazines across the world every month of every year, but the ones that just happened to appear this month are "eerily prophetic". :)

    • Re:Ha (Score:2, Insightful)

      by LostCluster ( 625375 )
      The fact is, a small little trade magazine article that only a few hundred people cared about last week is now interesting to nearly everybody this week.

      • Re:Ha (Score:4, Insightful)

        by Anonymous Coward on Sunday August 17, 2003 @08:59PM (#6719885)
        I would hardly call the IEEE Spectrum a "small, little" trade magazine. Every IEEE member gets a copy. There are well over 300 000 IEEE in the world. Circulation is at least thus 300 000. Here are the benefits [ieee.org] of such a membership.
    • Isn't anthropic thinking wonderful? :)

  • Grabby headlines (Score:3, Funny)

    by Faust7 ( 314817 ) on Sunday August 17, 2003 @08:28PM (#6719747) Homepage
    Steady As She Blows

    Looks like they're hard-up for readers. ;-)

  • Simple Tweakage (Score:3, Interesting)

    by EvilTwinSkippy ( 112490 ) <yoda@nOSpAM.etoyoc.com> on Sunday August 17, 2003 @08:35PM (#6719782) Homepage Journal
    The problem with power distribution is an imbalance between supply and demand. More efficient switching systems are like tossing a coffee can tailpipe on a honda. Sure you get a few extra horses out of it, but a Taurus with a 3.6 liter V6 is going to leave you in the dirt.

    We either need more power plants, to curb demand, or a fairly efficient way of storing excess power capacity in the winter to be used in the summer.

    Everything else might buy you time, but it is only delaying the inevitable.

    • Re:Simple Tweakage (Score:5, Interesting)

      by evilWurst ( 96042 ) on Sunday August 17, 2003 @09:15PM (#6719955) Journal
      "or a fairly efficient way of storing excess power capacity in the winter to be used in the summer. "

      Storing a season's worth of extra power for a season's worth of time is unworkable. However, storing excess power during the low-demand part of the day to ease spikes in demand later that same day...that is being worked on already. It was in either Discover magazine or the MIT Technology Review, but they're working on what is basically a huge fuel cell battery. Right now it's just at a military base, but the idea is to put one of these big batteries in every major city to act as a buffer. It'd ease both the peak demand on the power plants AND some of the stress on the transmission lines.

      • Storing Excess Capacity (Score:5, Informative)

        by Alan Cox ( 27532 ) on Monday August 18, 2003 @07:01AM (#6721486) Homepage
        In the UK we have at least one pump storage station for evening out loads - but not for months at time. Its basically two large lakes one above the other, excess power pumps water up, then when there is a surge in demand it goes back down through a generator.

    • Re:Simple Tweakage (Score:2, Interesting)

      by Anonymous Coward
      What about water?? If you pump the water up at night and in the day you let it run a turbine it would give you stored power.

    • Re:Simple Tweakage (Score:5, Interesting)

      by csbruce ( 39509 ) on Sunday August 17, 2003 @09:40PM (#6720055)
      We either need more power plants, to curb demand, or a fairly efficient way of storing excess power capacity in the winter to be used in the summer.

      All you need is a means of storing off-peak supply for on-peak demand. I hear that in British Columbia, they pump water back up into hydro-electric reservoirs during the night. Maybe regular power plants can have big flywheels.

      We can blame the environmental movement for there not being enough power plants.

      • Re:Simple Tweakage (Score:5, Interesting)

        by nhavar ( 115351 ) on Sunday August 17, 2003 @10:55PM (#6720283) Homepage
        Bullshit, we can blame ourselves for overconsumption and the NIMBY's (Not In My BackYard) more than the environmentalists.

        I hate that knee-jerk response to everything - "It's the environmentalists fault".

        Even with all the technology that we've created to make lower power devices we just find a way to get more devices. I saw how they were working on LED's as a better, more efficient lightsource that can do task lighting for about 1 watt of power. I mention this at work and some jackass comes up behind me and says how cool it would be to be able to have a wall full of them and be able to change the color of his walls with his mood - POWER SAVINGS - what power savings?

        It's a balancing act. First we have a grid that's just too old and extremely expensive to update. There's a mix of powerplants that are aging, there's poor planning, no incentive to change energy usage habbits, poor city design that promotes heat which in turn increases energy consumption due to airconditioners, extra showers, fans, and refridgerators. Then you have people who don't want a soot belching powerplant in their backyard, or off their favorite camping spot, nor do they want to pay extra for a more expensive cleaner burning plant, or pay extra tax dollars to have research into alternative plans like more efficient solar/wind/water/et al. Somewhere in there you have the environmentalists trying to conserve as much of nature as humanly possible before we end up having to chop down all the trees just to put up oxygen factories because we cut down too many of the fucking trees.

        Noone wants to compromise their lifestyle to get to plan X, Y or Z.

        My feeling is that we need a decentralized system where power is created in much smaller "nodes" and distributed from those points. Nodes could be created in house basements or in larger buildings and be connected to more evenly distribute power over shorter distances reducing the waste that happens when power has to be transmitted over miles and miles of cable to a destination. Additional efficiencies could be found as nodes throttle based on time of day and demand for their area. Grid failures would be reduced because nodes could throttle based on the failure of other nodes. We need more expensive but higher efficiency (and somewhat safer (no oil fires)) superconductor main lines. We need more incentive and more instructions on how we can save power and reduce use and what power saving products are good and can in turn save us money. We need much more diverse power sources Wind/Sun/Hydro/GeoThermal/FuelCell/Gas/Cleaner-Saf er Nuclear in much higher mix than we do today. We also need more cradle to cradle industries that take waste products and turn them into fuel for the next industry - reducing power consumption and limiting the need to dig more out of or cut more off of the earth.

        I want giant catapillar like machines like TBM's that crawl through landfills chewing up trash and spitting out useful products. Sorting all the garbage into recycled materials and fermenting the rest as fuel to continue on in it's job or produce energy for nearby cities.

        I want to see someone come up with a plan that doesn't attempt to single out ONE group of people as THE PROBLEM.
        • you have people who don't want a soot belching powerplant in their backyard, or off their favorite camping spot

          Ironically, the newer plants produce almost no visible exhaust comapred with the older ones that would then be retired. New power plants = less pollution.

          Some environmental organizations have figured this out. In CA, a big deal was made over how the Central Valley Sierra Club was in favor of new power plants - this was exactly their reasoning.

    • "...or a fairly efficient way of storing excess power capacity in the winter to be used in the summer."

      Wow! To me that sound *so* wrong. =)
      Consuming more power during summer, that is...
      We've got exactly the opposite problem. During winter we must heat and light our homes more and people are more indoors, doing stuff that requires electricity. Like watching tv and using their computers. =)

  • Management *is* key... (Score:5, Interesting)

    by neiffer ( 698776 ) on Sunday August 17, 2003 @08:37PM (#6719787) Homepage
    The critical point here is that to have "exotic" devices, you have to be able to manage them to make the power grid meaningful stability. Often, the hip environmental crowd (okay, so I am often one of them), complains that there isn't enough use of alternative energy in the mainstream grid. However, if we dedicated a meaningful amount of the grid to energy extracted from yak dung, what happens if there are problems? The grid elsewhere has to make up the slack (often at a higher price and inefficient) or we have problems like last week. The more technology develops, the more we are likely to be able to use alternative energy...goo goo gah joob.

    • Re:Management *is* key... (Score:5, Insightful)

      by Anonymous Coward on Sunday August 17, 2003 @08:55PM (#6719875)
      The key is nuclear power.

      Coal power is ok, it is cheap it is cleaner then it use to be, like everything else technology has improved it 300% since the 1970's.

      Natural gas/oil is the favorate right now. Unfortunatly our government isn't allowing us to tap the gigantic resources we have so we are running out of it. We have enough oil in our country to last us another 30 years easy(with projected increases in consumption), yet we depend on the dildo's from OPEC, but that is ending with eastern european countries and russia getting into the market.

      Hydrogen economy. What a freaking joke. I can't beleive that people fell for this crap. The energy has to come from somewhere, right now it comes from oil. So hydrogen would actually be wastefull and increase pollution. Why don't we just power our cars from rocks tied to ropes on long poles? We lift the rocks up, tie them to cars, drop the rocks and the rope would be tied to a pully attacted to the wheels. WEEE!!!

      Water, wind, solar. Most places do not have enough wind/sun/water to power anything meaningfull. Maybe if we kick everybody out of montana and fill the entire state full of wind farms me MAY just have enough power to run parts of californa. Well only during parts of the year.

      Nuclear: Lots of power, lots of fuel. We can power a large city for ten years with a handfull of pellets. The waste is insigificant comparied to the waste from other sources of fuel. The only thing standing in the way is ingnorance. Pure and simple. We have thousands of nuclear plants all over the country, they have one minor burp of gas from one plant and people are freaked out for decades. All these plants are running from late 1970's technology at best and they are perfectly safe. Of course unless they are soviet power plants whose "waste" was designed to be nuclear weapons grade-able. Such a freaking joke. Ignorance is what is standing in the way and the vast majority (not all of course) of anti-nuclear freaks are the modern day equivelent of Luddites
      • Well, Ogg the CaveMan would fully support the rocks tied to ropes method!!! At least when he wasn't smashing Open Source CDs...
      • True, the anti-nuclear crowd are a bit dogmatic, you forget the real issue with nuclear power. Where do you plan to put the waste, huh? Yucca Mountain? You mean the storage facility on the quake fault line? Nice. :) Nuclear is a good prospect but relying on a single source is what doomed our system in the first place. Variety is the spice of the power grid, my friend.
        • True, the anti-nuclear crowd are a bit dogmatic, you forget the real issue with nuclear power. Where do you plan to put the waste, huh? Yucca Mountain? You mean the storage facility on the quake fault line? Nice. :)

          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.
      • Question for you: Has it ever been proven that Nuclear power plants generate more energy in their lifetime then is needed to construct them ?

        I read somewhere that they don't, but it could have been FUD

        • Has it ever been proven that Nuclear power plants generate more energy in their lifetime then is needed to construct them ?

          The rule of thumb is that a nuclear plant will take about a year to generate the energy needed to construct it. Overall energy efficiency would be increased by allowing the plants to operate as long as it is safe to do so.

          Probably the key issue with plant longevity is the embrittlement of the pressure vessel by neutron irradiation (and there are techniques to reduce that problem).

      • Re:Management *is* key... (Score:4, Funny)

        by aled ( 228417 ) on Sunday August 17, 2003 @11:10PM (#6720323)
        I don't know why so much fear on nuclear power. After all if there is an accident, we all get superpowers.
    • The killer app here is the "large battery" that can take in excess power and give it back when we need it. Of course, real world problems like loss, reaction time, and how you make sure such a thing doesn't explode are standing in the way. It's going to take a lot of science work to solve this problem, but the payoff will be huge once it is solved.
    • No - the key is to have a decent method of yak-frighening, allowing the production of fuel on demand.

  • Interesting Article (Score:4, Funny)

    by notque ( 636838 ) on Sunday August 17, 2003 @08:38PM (#6719789) Homepage Journal
    Impressive as the gains have been, it isn't quite clear yet that the wind can blow a fat cock up the ass of the developed world's fossil-fuel dependence.

    What sort of tools would you use to determine that?..

  • fuel cell (Score:5, Interesting)

    by fishbert42 ( 588754 ) on Sunday August 17, 2003 @08:50PM (#6719848)
    About two years ago I went to the Electrical Manufacturing and Coil Winding Association's Expo in Cincinnatti, OH. There, they had a number of seminars on fuel cell technology. There was much talk about the (at the time) brand new hybrid cars from Toyota and Honda, using fuel cell technology to power personal electronics, the challenges left to face in making fuel cell technology practical, etc. One possible future that was presented (15-20 years down the road, so they said) was having a large fuel cell power your entire home. I mean, it's your house, you could theoretically put it anywhere you want (even underground) so that it's out of the way, right? Residential electrical service might consist of a truck coming by to refill your home fuel cell every month or two. Anyway, if such a future were to come about, rolling blackouts like what we saw (or didn't see, come to think of it) in New England and eastern Canada could very well become a thing of the past.

    Food for thought. But there's no guarantees that it's not half-baked. =)

    • Re:fuel cell (Score:5, Insightful)

      by michael_cain ( 66650 ) on Sunday August 17, 2003 @09:32PM (#6720027) Journal

      Lots of stories about home fuel cells powered by natural gas, like this one [visteon.com]. No trucks, since most local codes would not allow you to store two months worth of liquified natural gas in your garage or backyard. Heavy dependence on the natural gas delivery pipes. Some potential problems (all amenable to solution, I believe, just be prepared to spend money):

      • In part because so many electric generating companies have decided to use natural gas for their newest plants, there are forecasts of shortages and substantial price increases starting this winter. Such shortages would be worse if there was a sudden large demand for gas to generate household electricity in areas currently using coal or petroleum.
      • Overseas transport of gas is much more difficult than petroleum. IIRC, Saudi Arabia produces enormous amounts of gas as a byproduct of their oil wells. Shipping it is so complex and expensive that they simply burn it off at the wells rather than trying to sell it.
      • Long-haul gas pipelines are subject to spectacular local failures. Recently saw one in action -- an 18" pipe ruptured and the gas ignited. Flames shooting several hundred feet into the sky. Impressive!
      • I do not believe that the national gas pipeline infrastructure has the same degree of interconnection that the power distribution grid has. This might be good -- no cascading failures. This might be bad -- lose one pipeline and large areas run out of gas/power as soon as local storage facilities are exhausted.

      • Re:fuel cell (Score:3, Funny)

        by dogfart ( 601976 )
        I see a Slashdot poll coming! :

        What is your favorite source of natural gas?

        Looking forward for voting for the "cowboy neal" option.

  • Hello, a VOLTAGE REGULATOR, perhaps?!?!? (Score:2, Interesting)

    by Anonymous Coward
    Take the most common electrical generator most of us own, the alternator in your car. This item is driven by the engine's crankshaft, and it's speed goes uo as the crankshaft's revolutions speed up. Of course too fast, and the power the alternator makes will cook the battery (which it feeds). Hence the built in voltage regulator that all alternators have. Is the answer so obvious that they have missed it?

  • The problem with power distribution (Score:3, Insightful)

    by Anonymous Coward on Sunday August 17, 2003 @08:54PM (#6719866)
    The problem with power distribution is the medium: electric power lines. It makes more sense to generate power cleanly and locally, with fuel cells at the core of the distributed power generaters. For fuel you use hydrogen reformed from fossil fuels or hydrogen rich biomass, or hydrogen created from excess wind, solar, or any other source. Then transmission lines don't matter so much, pollution is reduced, and the world is a happier place.

    • Re:The problem with power distribution (Score:4, Insightful)

      by LostCluster ( 625375 ) on Sunday August 17, 2003 @09:39PM (#6720050)
      The power industry would love for everybody to have power natural power generation systems like windmills or solar panels in their yard, and then connect to the grid to either buy more or sell back when the backyard system can power the house with room to spare. It'd be a win-win for everybody, because it's a known fact that the less wire distance you have to move power, the less you end up losing in the transfer process.

      The problem is, there's an annoying group of "environmentalists" who call windmills eyesores... and that's why this idea isn't taking off.

      The problem is, hardly anybody's willing to go for it.
      • The problem is, there's an annoying group of "environmentalists" who call windmills eyesores... and that's why this idea isn't taking off.

        No, the problem is that almost nobody's back yard is windy enough to economically produce wind-generated electricity.

        Anyway, the people complaining about the aesthetics of windmills in your back yard wouldn't be environmentalists. They would be the anal members of your subdivision's architectural control committee: The folks who send you letters if your flower beds h

  • One of the issues that stops wind power. (Score:5, Interesting)

    by DAldredge ( 2353 ) <SlashdotEmail@GMail.Com> on Sunday August 17, 2003 @08:54PM (#6719870) Journal
    Is that some rich 'environmentalists' don't want wind power where they can see it.

    http://www.startribune.com/stories/484/4041637.h tm l

    I guess that wind power is OK as long as it is in someone elses backyard...
    • yeah, nobody wants a power plant in their back yard. It is funny how conservatives are not eager to have coal burning plants next to their houses either.

      But of course that issue has nothing to do with the decision to build wind power plants.

      The "not in my back yard" problem is very old and there are ways to deal with it.
      • A very easy way of dealing with NIMBY is community involvement, as we [windshare.ca] have done in Toronto. Since "your own pigs don't smell" (which I'm told is a Danish expression), if a wind turbine or wind farm is owned by the community in which it is sited, more people feel involved, and fewer feel threatened by it.

        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 uno

    • I've brought this up on slashdot before, but strangely nobody has been able to demonstrate any points, either pro or con, about this claim. Since I'm not immediately hopping on the 'windpower is perfect' bandwagon, people might try to accuse me of being a "rich environmentalist" as the parent refers to anti-windfarmers, but let's burn some karma anyway.

      Basically, wind turbines may introduce other environmental problems, just as most other energy plants do. They're not entirely "clean" as many would like

  • Switch to DC (Score:2, Flamebait)

    by amorsen ( 7485 )
    It's much easier to regulate DC with power electronics. AC was needed back when the only way to change voltage was using a transformer. Now it is obsolete.
    • I know at least in mocroprocessors, wires that contain DC current that is always in one direction have a tendency to break...
      • The reason for this is that the constant electron drift in the wires breaks the wires down by moving the atoms slowly farther down stream by collisions. Eventually a point is created in the wire that is thinner than normal and the effect magnifies and dramatically increases the impedence in the wire. If the wires have currents traveling in both directions the effect has a tendency to canel itself out I guess.
    • Mod the parrent post funny... it's clearly a joke. Swapping standard to metric never went over well, swapping IPv4 to IPv6 is stuck in the mud... swapping everything that plugs in over to DC is just plain not gonna happen.
      • It already happened. Old-fashioned light bulbs are still running 50 Hz AC. Those bulbs would run just as well on DC. Everything else is either converting to DC or switching much faster than 50 Hz.

    • Re:Switch to DC (Score:5, Interesting)

      by bluGill ( 862 ) on Sunday August 17, 2003 @09:28PM (#6720008)

      DC still isn't perfect. When you get voltages high enough you can no longer make a circuit breaker for instance, because the sparc never stops. (There are solutions, most involving blowing something in the breaker so the plasma of the arc doesn't complete the circuit)

      DC is also more dangerious. AC crosses 0 volts 120 (100 in europe) times a second, so if you touch a line and it doesn't fry you instantly you can let go, sort of. DC forces your muscles to contract, which can cause you to grab the conductor harder. (depending on how it effects you, it can also throw you violently away from the conducter). AC will relaxs those muscles several times a second giving you a chance to let go. And don't forget the arc in the previous paragraph if you do manage to let go of a DC line.

      Of course in the voltages involved with cross country power transmission it is all theroitcial nonsense, you die either way. In lower voltages it can make a difference. Eventially voltages get low enough that it doesn't matter. Unfortunatly without knowing exactly where and how the power travels though you nobody can tell what will happen in any particular case, which is why we tell people to stay away.

      As a last point though: induction moters cannot work without AC. This isn't going to be a point for much longer though. Already some manufactures are finding that it is better to use electronics to make their own AC to their specs. (Some maytag washers for instance use 3 phase moters, and the controller not only generates AC in the required 3 phases from the one phase that comes in, it sets the exact speed they want the moter to turn at eliminating complex gear boxes)

      • As someone who's grabbed a live wire I can tell you that AC current does NOT make it easier to let go of anything. It lets your muscles relax sevel DOZEN times a second. Have you ever tried dropping something while you're having a seizure from hand to grounding?
    • You obviously have no concept of AC and DC electricity. Its not just a matter of stepping voltages, its also a matter of line losses and safety. High DC voltages are much more dangerous than similar AC voltages. On top of this, the line losses would make long-range transmission of DC power impractical.
    • I believe that AC was chosen not only because it was safer, but becasue it was FAR easier to transmit over long distances. As far as I know those two things are still the same. AC is what we have, and besides, do you really think that switching to DC will solve problems? If the problem was the overburdened grid, the same thing would happen. And let's not forget all the trouble and fried electronics that would result during the switchover.
      • AC at 10,000 V is not safe. DC is easy to transmit over long distances now, because power electronics are used to boost the voltage (a la switching power supplies). If the problem was the overburdened grid, the same thing would NOT happen with DC: as a matter of fact, it is proven it DIDN't happen. Quebec uses HVDC transmission lines. The HVDC lines created a buffer zone that isolated Quebec from the frequency- and load-related problems that shut down the AC grid last week. With DC you don't have reactive
        • DC can't be easily transmitted over long distances, that's why AC is used for the power grid instead of DC.
          • Did you not read what I said? Quebec uses DC for long-distance transmission, because it is more efficient than AC at extremely long distances. The Quebec DC line is so long that a solar flare induced several million volts across it.

    • Re:Switch to DC (Score:4, Informative)

      by Victa ( 186697 ) on Sunday August 17, 2003 @09:41PM (#6720058)
      Unfortunately DC power distribution is highly inefficient. When transmitting power down a long lenght of wire DC creates a much higher voltage drop (power loss) across the line than AC.

      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...
      • Unfortunately DC power distribution is highly inefficient. When transmitting power down a long lenght of wire DC creates a much higher voltage drop (power loss) across the line than AC.

        I don't see how this is the case. For both DC and AC signals, you have to worry about the bulk resistance of the cable, which dissipates roughly the same amount of energy in each case (off by a factor of sqrt(2) or so, but not by a vast amount).

        For DC and AC, you lose due to corona discharge through the atmosphere, but the
        • But the corona and bulk resistance losses scale with the voltage, so you end up losing more power this way.

          Modification: Resistive losses go down as voltage goes up, for fixed power, because current is lower, resulting in a lower voltage drop for a fixed bulk resistance. But this holds for both DC and AC, so the net effect is nil.

          Before anyone mentions skin effect for AC changing the effective resistance (making AC worse), at frequencies this low it's negligeable.

      • Re:Switch to DC (Score:3, Interesting)

        by shoemakc ( 448730 )

        " 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)."

        I'd say it had more to do with the difficulty in steping up and steping down voltages for long distance transmission before the advent of power electronics. Compare this to a common transformer which was well within the technology of the late 1800's. Actually, besides the transmformer problem, DC systems are actually

  • The Y2K bug... A flashback (Score:5, Interesting)

    by RedCard ( 302122 ) on Sunday August 17, 2003 @09:02PM (#6719908)
    Here's a question that I haven't seen asked yet... everyone's comparing this whole thing to the blackout of 1965, but what about the backups that were supposedly put in place to deal with the much-feared and hyped Y2K bug?

    Wired 7.04 published an issues entitled 'Lights Out' [wired.com] that detailed many problems, including the problem of a single failure spreading across the entire continent.

    Billions were spent in the USA and Canada on solving this... so where did that money go?

    • Billions were spent fixing the problem. Because the problem was fixed before 2000 there was no problem! Now people think it was wasted money because there wasn't a problem.

      More importantly though, the power grid wasn't greatly at risk. Much of it was still mechanical systems, or embedded systems that don't know the date anyway. (In many cases nobody set the date when the equipment was installed, so if it even keeps track of a date, it is a default date that is wrong)

      Do not confuse a diaster avoided

      • I think the parent was more concerned that all that money was spent and there WAS a problem...last thursday! The Y2K fix wasn't just to fix date handling, it was to make sure that if there WERE any date-related outtages, it wouldn't shut the entire grid down. And BOOM here we are, an outtage and the entire NE grid goes down.

  • rock the vote (Score:3, Informative)

    by segment ( 695309 ) <sil@poli[ ]x.org ['tri' in gap]> on Sunday August 17, 2003 @09:09PM (#6719934) Homepage Journal

    For those unaware of what's going on, here is a quick excerpt of President Bush denying money for a secure grid...
    By Peter Behr and James V. Grimaldi

    Washington Post Staff Writers
    Sunday, August 17, 2003

    The Bush administration intends to side with a Senate Republican attempt to freeze a disputed regulatory proposal meant to strengthen the nation's aging power transmission system, which was blamed in last week's massive blackout, a senior administration official said yesterday.

    (Source [politrix.org])

    On top of this it was announced that grids would be targeted by terrorists.

    US electrical grid a prime terrorist target By Knut Royce Washington August 18, 2003 Like virtually all of America's infrastructure, the electrical grid is vulnerable to isolated terrorist attacks that could create disruptions similar to the recent blackout. A growing number of security experts, in and out of the Government, worry that potentially hostile states and even a rebuilt al-Qaeda could wreak havoc through simultaneous and co-ordinated assaults on sensitive points on the grid.
    (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:rock the vote (Score:4, Insightful)

      by baseinfinity ( 18023 ) * on Sunday August 17, 2003 @09:56PM (#6720107)
      Sorry, I just don't see how terrorists would be motivated to try to cause blackouts.

      Sure, they cause inconvenience and economic losses: but these are people who want to mess with our heads. The lights go out, people walk home, a little miffed, life goes on. A major building blows up and people are quite a bit more afraid of the world.

      They managed to get the grid up mostly over the weekend. I'd say for something as complex as the power grid over 5 states that's pretty damn good. It'd cost billions upon billions to retrofit our power grid to something modern using some accelerated schedule, and I don't see how you expect our president to be jumping to spend any more money just because we had a so far isolated incident.

      There's already plans in place to upgrade our systems over time, you can easily read about them in these articles. Bush may be a bad president but I don't see how any president should be so swaded policy wise by every incident that happens to a very large and complex country.
    • The Dems in the NorthWest oppose this as well.

      http://www.katv.com/news/stories/0803/98999.htm l

      Opponents argue that the blackout occurred in a region where just such a type of grid management has been touted.

      "The (FERC) measure ... goes to the question of whether or not we would mandate and force down the throats of regional areas of the country a federal approach to deregulation of the marketplace"

      "Deregulation has left us without adequate consumer protection and safeguards like reliable service and p

  • Why not (Score:2, Interesting)

    by BigBadBri ( 595126 )
    take a leaf out of the solar power generators referred t oa couple of weeks ago?

    Rather than having massive acapcitor banks to balance the load, what's to stop us letting the windfarm run free, using all the energy to liquefy salts (by simple heating elements with low inductance, so phase-lag isn't an issue), then feeding the heat energy into the grid via turbines?

    Either that, or have a big capacitance and an invertor on each windmill.

  • Nice to see our patent system working (Score:5, Insightful)

    by Edmund Blackadder ( 559735 ) on Sunday August 17, 2003 @09:31PM (#6720023)
    Towards the middle the article explains how the europeans deal with the problem ... they just use improved turbine designs. After you see the following paragraph:

    "The idea has been slower to catch on in the United States, where GE Wind Energy, in Tehachapi, Calif., has deftly defended patents on variable-speed turbines that will be on the books through 2011. "

    Nice to see the patent system working again. I guess the Europeans were lucky because GE Wind energy decided not to file their patents in europe (or they were not granted).

    But then again, shouldnt patents help innovations ... isnt that how it was supposed to work. Shouldn't variable speed turbines be much more developed in the us because they were patented here?

    Frankly i dont know why GE systems does not promote variable speed wind turbines now that they have the protection, and if they cant, why they dont sell affordable licences to companies that can. It could be due to the usual burocratic inefficiency, or it could be something sinister.

    Yet this is not the first time i see an owner of a patent sit on the technology and not develop it while other people are perfectly able to do so. We all remember how a company that does not take the trouble to make portable email devices, tried to stop a company that does make them.

  • Doesn't quite ring true (Score:5, Informative)

    by Willard B. Trophy ( 620813 ) on Sunday August 17, 2003 @09:36PM (#6720040) Homepage Journal
    As someone who built wind farms for four years, and is now a director of Canada's first urban wind power co-op, WindShare [windshare.ca], I'm not convinced that this article really accounts for much.

    While it's true that most wind turbines use induction generators, they do so for several reasons, including:

    • safety: as the wind can blow at any time, an alternator could energize a powerline that's down for maintenance. Induction generators need line (excitation) current to get them going, and thus they won't frazzle an unsuspecting worker.
    • stability: an induction generator's torque/speed curve matches that of a stall-regulated wind turbine. Thus a wind turbine of this type will tend to run at a constant speed.

    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 ...

  • Wind is only part of the answer. (Score:5, Informative)

    by Zebra_X ( 13249 ) on Sunday August 17, 2003 @10:00PM (#6720116)
    GE manufactures a turbine rated for 3.6MW [gepower.com] output. Ge is currently an industry leader in these types of turbines though, they are desiged primarily for offshore use. Smaller MW ratings between 1.5 and 2.8 are more common. Unfortunately, even with wind turbines producing @ 3MW it would require approximately 1.26 Million of them to meet the U.S.'s current power demands. Currently Coal plants are responsible for the majority of our power capacity in the U.S.

    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.

  • home use?? (Score:4, Interesting)

    by canning ( 228134 ) on Sunday August 17, 2003 @10:01PM (#6720122) Homepage
    Has anyone from Slashdot researched a home version of these wind turbines? Anything that would decrease monthly power bills involving a clean energy source is alright in my books.
  • Surplus electricity that cannot be consumed by nearby grid users can be used for an electrolysis process to produce hydrogen. The hydrogen can then be stored and distributed for fuel cells.

    www.virtualeli.com

    • Re:use surplus electricity for electrolysis (Score:5, Informative)

      by Dun Malg ( 230075 ) on Monday August 18, 2003 @02:24AM (#6720917) Homepage
      Surplus electricity that cannot be consumed by nearby grid users can be used for an electrolysis process to produce hydrogen. The hydrogen can then be stored and distributed for fuel cells.

      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.

  • MSBLAST initiated Power Fallout ? (Score:3, Informative)

    by stock ( 129999 ) <stock@stokkie.net> on Sunday August 17, 2003 @10:46PM (#6720250) Homepage
    Here's some info :

    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]
    http://www.securityfocus.com/archive/1/333513/2003 -08-13/2003-08-19/0 [securityfocus.com]
    http://www.automationtechies.com/sitepages/pid641. php [automationtechies.com]

    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

  • Transient stability is the answer. (Score:2, Interesting)

    by Anonymous Coward
    My Step-fathers brother, a college professor at a major university, has created a software routine that will compute the transient stability of the entire North American power grid in a few seconds on a cray super-computer. With this software a loss of one line would keep the lose on that one line instead of cascading the problem throughout the grid. It would also have the benefit of maximizing the power that flows throughout the system. It has also been run on PG&Es old Apollo computers. They were do

  • Distrubuted electric balancing (Score:5, Informative)

    by silverhalide ( 584408 ) on Monday August 18, 2003 @12:59AM (#6720712)
    This is one area that electric cars may be able to provide a valuable service in what's known as vehicle to grid. A small company in california has been doing a lot of research [acpropulsion.com] on the topic and it looks promising. Theoretically, if you get enough electric cars that are plugged into the grid whenever they're not in use, they can provide near-realtime load balancing by remote dispatching from the power company. Say the power surge that took out the grid happened, but this time with a few hundred thousand electric cars plugged into it. The company could send a broadcast to the cars to absorb the extra load within a few seconds, and stop the cascading failure. Conversely, if there's a sudden demand spike, the cars could be ordered to temporarily supply it until the spike subsided. Obviously there's many technical hurdles but the general idea is very cool.

  • Coincidentally... (Score:3, Interesting)

    by pjt48108 ( 321212 ) <{mr.paul.j.taylor} {at} {gmail.com}> on Monday August 18, 2003 @08:39AM (#6721960)
    About a half-hour prior to the blackout, I was reading an article online--I forgot the URL completely--which discussed the use of superconductors to augment the circuit breaking elements of the power transmission system.

    Now, IANA Electrical Engineer, however, I found it interesting, in hind sight especially, that these superconductive elements would be used to soften the blow on circuit breakers, which sometimes cannot react to an overwhelming surge, which will blow right through them.

    I won't go into the details, especially as I don't have the article before me for cut-n-paste cheating. However, it was intriguing that superconductors, in this case, were proposed for use not as conductors, but instead to react by becoming less-conductive with the increase in flow, etc, in a much faster manner than the mechanical breakers.

    Now, if we could only get some wind farms up and running here in Michigan, and in substantial numbers... (I've seen the one in Southeast Wyoming, and it was truly awe-inspiring!)

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