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Power Electronics Help to Control Electrical Grids

michael posted more than 11 years ago | from the dust-off-physics-101-knowledge dept.

United States 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."

Sorry! There are no comments related to the filter you selected.

FP (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6719696)

FP!

Dupe? (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6719701)

Isn't this a dupe, or was it just mentioned in a post somewhere? Can't remember...

Mirrored text here - slashdotted already... (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6719705)

Steady As She Blows

Power electronics and exotic energy storage devices are making wind power steady enough to compete with conventional electricity sources

By Peter Fairley

In this season of discontent in the electricity business, only wind power seems to stand out as a global success story. While petroleum prices were convulsing in response to war and labor strife, and nuclear plants were stoking controversy in the Middle East and Asia, wind turbines were quietly becoming the fastest-growing energy source in the world. They now provide more than 31 000 MW of power, a total that has swelled by almost 30 percent in scarcely a year's time and that keeps more than 200 million tons of carbon dioxide out of the atmosphere every year. Wind power's ascendance has been so stunning that advocates are now rallying around an idea that would have seemed preposterous just a couple of years ago: that the wind could supply 12 percent of the world's electrical demand by 2020.

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. One of the most important reasons is that clean, renewable wind power comes with a serious hitch: while conventional power plants yield a steady stream of electricity, wind turbines often ply turbulent gusts and therefore spit out an irregular stream of electricity that is tough for power grids to swallow.

Now, though, high-tech solutions are at hand. Systems based on advanced power-electronics and energy storage devices are massaging and managing power flows from wind turbines, enabling them to contribute mightily to electricity grids without putting those grids at risk. Not only are the technologies making wind power more palatable to grid operators, they are even making it possible for engineers to finally harness wind energy's tremendous potential in wind-swept, remote locales.

Perhaps nowhere is this potential so evident as in the state of Hawaii, whose isolated power grids could not otherwise risk taking full advantage of the archipelago's abundant, renewable resource. In fact, with its lush, endless trade winds and growing commitment to wind power, Hawaii's Big Island is emerging as a laboratory of the future of the technology. As wind power becomes a steadier and more reliable resource, it could help wean power producers all over the state from their dependence on costly imported oil.

But, for now, says Karl Stahlkopf, chief technology officer at Hawaii Electric Co., in Honolulu, even the existing wind farms on the Big Island--putting out just
10 MW, the equivalent of four state-of-the-art wind turbines--make grid controllers hop on days when the palm fronds fly.

The utility and its contractors plan to build what Stahlkopf calls an "electronic shock absorber" to buffer the island's power grids against the wind's worst behavior. It's a development that engineers elsewhere are following closely.

The reason is that the solutions to integrating modest levels of wind power on small, isolated grids today may foreshadow the installation of truly large-scale wind power in mainland networks five or 10 years from now. "What's happening in the Hawaiian Islands is a peek at the future," says Bob Zavadil, an expert on wind power at the Arlington, Va.-based power systems analysis firm Electrotek Concepts Inc. "They're on the leading edge." And that's true not only of the technology but also of the new legal and regulatory conventions between utilities and independent power producers that will be needed before wind energy can truly thrive.

Reactive Power 101
Back on the mainland, wind farms have grown to dozens of turbines and hundreds of megawatts--rivaling the size of conventional power plants. To pave the way for installations like those, engineers had to grapple with the tendency of wind turbines to introduce voltage instability into electrical grids. That tendency follows from the intermittent nature of wind-generated electricity, which waxes and wanes in irregular episodes unrelated to the predictable daily ebb and flow of consumer demand.

To understand the instability issue--and its solution--you'll need a few basics on the nature of power flows on utility grids. First, recall that these flows consist of both active and reactive power. The difference between them arises from the fact that the wave of alternating current on a power grid almost always leads or lags the voltage wave. In short, inductors, such as the coils in motors or transformers, cause current to lag voltage; capacitors cause current to lead voltage.

Active power is the familiar watts consumed by light bulbs and toasters; it is the product of voltage and the component of current that is in phase with the voltage. Reactive power, measured in volt-amperes reactive, or VARs, is the product of voltage and the out-of-phase component of alternating current. This out-of-phase power is consumed by energetic electric or magnetic fields--for example, in coils in inductive loads, such as motors, and also in the utility's own transformers. Transmission lines themselves are also inductive. In the case of wind-generated power, this line inductance can be a critical factor, because the turbines are usually far from population centers, strung out across windy plains or even areas out at sea.

Utilities have to pay close attention to reactive power because it determines, along with active power, how the voltage declines, or "sags," on an electric network. Utilities must keep voltages very close to rated values because when they fall too low, motors and other inductive loads draw too much current, overheating the equipment and possibly damaging it and other utility gear as well.

Declining voltage on a network is a function of the consumption of both active and reactive power. In other words, if a big load consumes lots of reactive power, it will cause the voltage to sag intolerably unless that reactive load is adequately compensated for. Because these reactive loads are almost always inductive, causing current to lag voltage, utilities must feed them with reactive power in which the reverse is true--with current that leads voltage.

For this they have several options. They can supply reactive power right from the generators themselves, by producing current waveforms that lead voltage. They can also install banks of capacitors close to big inductive loads. As the load rises, relays switch on the capacitor banks to add reactive power.

So what does all this have to do with wind power? Many modern wind turbines generate electricity with an induction generator, also known as an asynchronous generator. Conventional, fossil-fueled power plants, on the other hand, are built around synchronous generators. There's a big difference between the two kinds of generators: a synchronous unit can provide both active and reactive power, as noted above. An induction generator, on the other hand, provides active power but consumes reactive power. This characteristic, coupled with the wind's intermittence, plays havoc with utility grids.

"As the wind comes and goes, the voltage goes down and up right along with it," explains Bud Kehrli, manager of transmission and distribution planning for the power equipment maker American Superconductor Corp., in Middleton, Wis. You could handle the problem by switching capacitor banks in or out, but it takes lots of nimble switching to keep up with the ever-varying gusts. And switching a big block of capacitance in or out can swing the voltage up or down a few percent or more, a variation that is felt as an abrupt change in torque on the turbines' gearboxes. Slamming a gearbox like that repeatedly is a bad idea because it soon wears it out, and replacing one costs about US $200 000 in parts, labor, and other expenses.

Semiconductor solution
These are exactly the problems that power semiconductors are solving from Andalucia to Abilene. Consider the Foote Creek Rim wind project in southeastern Wyoming, one of the biggest in the United States. The installation, which feeds grids operated by the utility giant PacifiCorp, in Portland, Ore., includes 183 induction turbines installed over the last four years, which generate up to 135 MW--enough for 25 000 households.

In choppy winds, the switching capacitor banks were often a step behind the wind, leaving an excess or shortage of reactive power on the local 230-kV transmission line, a major conduit through which PacifiCorp moves power from large coal-fired plants in Wyoming to customers in six western states. As a result, voltage on the line would spike up or down by as much as 5 or 6 percent.

Until this year, PacifiCorp stabilized those lines by brute force: it simply idled dozens of wind turbines at Foote Creek, throwing away cheap, clean energy in order to ship its coal-fired power. But this past February, the company turned to power electronics for a more satisfying solution, installing a $1.5 million system of silicon switches designed and built by American Superconductor to dynamically adjust reactive power at Foote Creek.

The new system is called D-VAR, for dynamic volt-amperes reactive. It can provide up to 8 mega-VARs of reactive power continuously (or 24 MVARs momentarily). Best of all, it can inject this reactive power in increments of as little as 0.027 MVAR, and it can turn on a dime, going from, say, -8 MVARs to +8 MVARs in less than one electrical cycle, or 1/60 of a second. At Foote Creek, the D-VAR system also controls nine banks of capacitors, totaling 50 MVARs, switching these capacitors on and off and interjecting its own MVARs as necessary to provide a smooth and essentially continuous range of reactive compensation up to 58 MVARs [see illustration].

The secret of the D-VAR's success is the insulated-gate bipolar transistor (IGBT), which was invented at about the same time, 20 years ago, at General Electric Co. (Fairfield, Conn.) and at the former RCA Corp. IGBTs are like high-power cousins of the transistors in your computer or cellphone, and they function in the D-VAR system as rapid power valves, opening and closing many times per cycle to produce an alternating current waveform that mimics the effects of an ultraprecise, adjustable capacitor bank.

Inside the D-VAR is a direct current bus whose voltage of 750 V is maintained by transforming and rectifying voltage from the external bus fed by the wind turbines. The IGBTs, controlled by microprocessors, switch between the dc bus and the external bus at a pace fast enough to establish a carrier frequency at 3 kHz.

Switching in elaborate, precisely timed patterns, the IGBTs produce sine waves at 60 Hz by means of a standard technique called pulse-width modulation. The longer the IGBT switches dwell in the "on" state, the closer the sine wave gets to an amplitude peak. And the longer the IGBTs are off, the closer the wave is to zero amplitude. Before the sine waves are transmitted on to the external bus, they are filtered to remove the 3-kHz carrier wave, producing smooth 60-Hz waves.

By adjusting the on-off patterns of the IGBTs, the system controller can make the current sine wave lead or lag the voltage by any degree desired. However, D-VAR is set up so that it produces a waveform in which the current sine wave leads the voltage sine wave by 90 degrees, thus mimicking the effects of a capacitor bank. To vary the amount of reactive power the D-VAR is supplying--the "capacitance," you could call it--the controller simply adjusts the amplitude of the current.

Built-in chips
Given the commitment to induction generators on the part of heavy hitters like Japan's Mitsubishi Heavy Industries Ltd. (Tokyo), substations will provide a ready U.S. market for IGBTs and other power semiconductors from American Superconductor and rivals ABB Ltd. (Zurich) and Siemens AG (Munich) for years to come.

But in Europe, wind farm operators are taking a different approach to harnessing the wind--and to handling wind turbines' thirst for reactive power.

The impetus had nothing to do with reactive power. Developers were just trying to reduce the mechanical strain on large, fixed-speed turbines, whose rotors can stretch wider than the wingspan of a jumbo jet. Their solution involves building the silicon switches right into the turbine.

What makes it all possible is a shift in the technology of the turbines themselves: instead of induction generators, wind farm operators are now more and more favoring variable-speed generators that can absorb the force of a gust by speeding up. IGBTs and other power electronics in the turbine convert the variable-frequency "wild" ac from the generator into a steady sine wave synchronized to the grid (50 or 60 Hz, depending on where you are).

The beauty of this approach is that the same electronics can be programmed to simultaneously convert some of the turbine's active power into reactive power, as the network demands.

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.

Whether the power electronics are inside the turbine or in a substation, however, they are being used in new ways as wind farms become larger, more critical components of power systems. "Utilities are generally lining up to require that wind farms be able to provide dynamic reactive compensation, much as a conventional generator would be able to do," says American Superconductor's Kehrli.

That means being able to pitch in and help restore stability during a disturbance or some other crisis on the grid. In the past, when a generator failure or momentary short-circuit roiled a network, wind farms would automatically disconnect themselves. But now, most grid operators "want the turbines to ride through the disturbance," says Chuck McGowin, manager for wind power technology at the Electric Power Research Institute, a utility-funded R&D consortium based in Palo Alto, Calif. "It's a big shift."

The movement began in Europe, where, since this past January, for instance, the German utility E.ON Netz GmbH, in Bayreuth, has mandated a "ride-through" for the more than 5 GW of wind farms in its territory. That is, the turbines must continue to operate during "faults" when the voltage sags precipitously or the frequency deviates from 50 or 60 Hz. In recent months, utilities across the United States have begun to jump on the bandwagon. Suddenly, wind farms and turbine developers must alter their designs and operating procedures, particularly for voltage faults.

According to Craig Quist, a principal engineer at PacifiCorp, most wind turbines are programmed to disconnect themselves from the grid if voltage drops by 30 percent for 50 milliseconds--just a few cycles in the power wave. Once again, the ultimate solution may lie in power electronics. Substation semiconductors or bolstered on-board electronics can help wind farms ride through such events by generating extra reactive power to hold up the local line voltage.

No more trouble in paradise
Riding through voltage faults is just one of the challenges confronting Hawaii's Big Island, where Hawaii Electric and independent developers are considering proposals to boost wind power generation to 30-40 MW on a 150-MW grid. If it happens, the Big Island will be tapping wind power in the same proportion as Denmark, which gets about 20 percent of its power from the wind. But the Hawaiians will be doing it on a comparatively tiny grid lacking the stabilizing embrace of a continent-wide power grid.

The main problem is that bigger wind farms would amplify the impact of the wind gusts that are already taxing Hawaii's grid controllers. A 20-MW wind farm, for example, could surge by over 2 MW in just two seconds--much faster than the island's oil-fired generators could ramp down or up to balance supply and demand. Even momentary sporadic mismatches between supply and demand are unacceptable because they would alter frequency and voltage on the network, putting equipment at risk and causing lights to flicker.

To make sure that doesn't happen, Hawaii Electric airlifted Karl Stahlkopf to the island last year. He was a natural for the job, having led the development of a variety of power-electronics-based systems as vice president for power delivery and transmission at the Electric Power Research Institute. The giant shock absorber that Stahlkopf envisions for the Big Island would mediate between the power grid and the turbines, and it would combine power electronics with an advanced energy storage device, such as an ultracapacitor or a battery.

Slamming a gearbox repeatedly is a bad idea, because replacing one costs about $200 000

When the turbines are going full bore, Stahlkopf explains, the power electronics will divert some power into the storage system, drawing it out again when the wind dips. If the line voltage drops in a fault, the power electronics will dig deeper into the storage reservoir to generate reactive power and prop up the line. For the project, Hawaii Electric, the state, and the U.S. Department of Energy are now considering various storage technologies and capacities, and Stahlkopf reports that a shock-absorbing system could be on-line by the end of next year.

Meanwhile, wind farm developer Apollo Energy Corp. (Foster City, Calif.) is negotiating with Hawaii Electric to double its 9.8-MW Big Island wind farm at South Point [see photo] and it has proposed to connect the added capacity to the grid via a shock absorber similar in concept to Stahlkopf's.

The heart of Apollo's system would be 30 flow batteries from Menomonee Falls, Wis.-based ZBB Energy Corp. Flow batteries are a hybrid between electrochemical batteries and fuel cells. They use pumps to circulate a pair of electrolytes past an ion-exchange membrane similar to the ones employed in many fuel cells. Ions pass across the membrane from one electrolyte to the other to charge and discharge the battery.

The flow batteries in the system Apollo envisions could back up a 20-MW wind farm for several minutes. It wouldn't be cheap; building and operating the battery system could cost $1.8 million over its projected 17-year life span. But by keeping the wind farm going during the 200-plus hours each year when erratic winds would otherwise force operators to shut down some turbines, ZBB and its partners insist that the battery storage system would more than pay for itself--to the tune of $5.4 million over its lifetime.

Hawaii's wind dreamers are already looking beyond these grid-stabilizing systems to larger storage devices that could negate the ultimate challenge facing utilities with lots of wind power: keeping the juice flowing during the hours, days, or even weeks when the air is not. On average, wind turbines produce their rated power only 20 to 30 percent of the time. Really big storage systems, capable of storing at least tens of megawatt-hours of energy, could make wind power almost as "dispatchable" as that from a fossil-fuel plant.

Several years ago, Apollo Energy proposed installing a 10- to 11-MWh flow battery on the Big Island. And Stahlkopf has launched a research collaboration with local water authorities to test a lower-tech, but potentially more capacious, option. The idea is to piggyback on the Big Island's existing infrastructure of water mains and reservoirs to fashion a pumped-storage system that would push water to higher-altitude reservoirs when the wind was strong, and then let it fall through hydroelectric turbines to produce power when the air was still.

Rewriting the rule books
With power semiconductors and other technologies rapidly minimizing wind power's technical shortcomings, the hurdles increasingly seem to be contractual and regulatory. Utilities such as PacifiCorp, which had to foot the bill for the D-VAR installation that put an end to the voltage instabilities at Foote Creek, are rewriting their contracts to put the burden of integrating wind farms on their developers. "We got stung on the first wind farm, and we're not going to get stung again," declares PacifiCorp's Quist.

Lacking detailed standards for wind farm behavior, negotiations between utilities and wind farm developers can get ugly--even in paradise. On the Big Island, Hawaii Electric and Apollo Energy have been at odds for four years over Apollo's proposal to install newer, larger turbines at its wind farm. Its game plan to add the flow batteries didn't help matters. Apollo contends the battery system will make the wind installation a "firm" source of power--in other words, one that can dispatch power to help shore up the network in a crisis. State regulations generally specify that utilities must pay more for firm power.

Stahlkopf replies that Hawaii Electric isn't yet convinced that the flow battery will adequately protect the Big Island's grid. But he is confident that the two sides will find common ground in their negotiations.

Whatever agreement ultimately emerges, it is likely to push wind energy that much closer to the mainstream. And when regulations catch up to technology, wind energy--clean, renewable, and unaffected by geopolitical conflict--should come into its own as a steady energy source for these turbulent times.

Re:Mirrored text here - slashdotted already... (0, Troll)

TubeSteak (669689) | more than 11 years ago | (#6719739)

"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"

Wakey wakey mod's. Can you spell T.R.O.L.L.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719757)

Can you spell T.R.O.L.L.

Those of us who know basic English know that troll isn't an acronym and shouldn't be spelled as such.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719767)

T.R.O.L.L = spelling the word letter by letter.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719781)

Of course you spell a word letter by letter. How else would you do it? Its obvious what letters are in the word troll.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719795)

Its obvious? Who's obvious? I didn't see obvious post. It's a mystery to me.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719774)

Those of us who know basic syntax know a period can be used as a seperator. While clearly dashes are in order, i.e. T-R-O-L-L, I would not fault anyone trying to make it obvious to the mods that they F-U-C-K-E-D U-P!!!

Besides, how the fuck do you know it's not an acronym in another language? You sound a touch anglocentric to me.

Re:Mirrored text here - slashdotted already... (0)

Anonymous Coward | more than 11 years ago | (#6719796)

Please explain to me why the poster would post almost his entire message in English and then suddenly switch to another language.

There was no reason for periods to be used in the word troll since it is not an acronym (not in this context, anyway).

The use of hyphens is totally incorrect.

P.S. Slashdot is an American-centric website as you should know by now. If you don't like it, tough.

COPY AND PASTE TROLL! (0)

Anonymous Coward | more than 11 years ago | (#6719744)

Moderate parent down:

look:

The installation, which feeds grids operated by the utility giant PacifiCorp, in Portland, Ore., includes 183 induction turbines installed over the last four years, which generate up to 135 MW--enough for 25,000,000 vibrators and lighted dildos.

Moderators, please read before giving points (0, Offtopic)

zakezuke (229119) | more than 11 years ago | (#6719749)

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.

Righto-- I'd say this was a troll... unless having a cock up the ass would impact our global dependance of power.

Re:Moderators, please read before giving points (0)

Anonymous Coward | more than 11 years ago | (#6719764)

I think it would! It might help the mods to spot a TROLL everynow and again!

Re:Moderators, please read before giving points (0)

Anonymous Coward | more than 11 years ago | (#6719811)

I don't think having a cock up the ass would help moderators spot trolls. If you think about it, it's hard to get a cock up your ass when you are sitting down, unless the person is in front of you. I guess if you were bent over getting a cock up the ass, you could be reading the screen, but I honestly don't know how having a cock up the ass would help?

Anal sex isn't the solution to our problems, but feel free to experiment if that floats your boat :P

Re:Moderators, please read before giving points (0)

Anonymous Coward | more than 11 years ago | (#6719837)

You misunderstand me - it's not the cock in the ass per-se, but having a fat cock forced up their ass every time they mod up a blatant troll.

Re:Moderators, please read before giving points (0)

Anonymous Coward | more than 11 years ago | (#6720067)

But since according to gay people, every one is gay and/or lebian. Would poeple start to enjoy there rectel punishment, there by not making it punishment and making people find trolls and mod them up.

Of course when this happens we can use anal sex as a way to reworied people for moding up non-trolls

So you are right Anal Sex for us when we miss up but also for when we do good

Re:Mirrored text here - slashdotted already... (0)

papa248 (85646) | more than 11 years ago | (#6719778)


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. (emphasis mine)

Really? Hmm... these must be Germans?

SCO TROLL licensing (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6719784)

Of course, the concept of TROLLING is patented by SCO - a proportion of this post goes to them!

Control is the key... (5, Interesting)

The Eye of the Behol (678699) | more than 11 years ago | (#6719711)

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... (4, Informative)

LostCluster (625375) | more than 11 years ago | (#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... (4, Insightful)

Edmund Blackadder (559735) | more than 11 years ago | (#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.

Ha (5, Insightful)

pokka (557695) | more than 11 years ago | (#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 (2, Insightful)

LostCluster (625375) | more than 11 years ago | (#6719738)

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 (4, Insightful)

Anonymous Coward | more than 11 years ago | (#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.

Nice benefits (1)

bersl2 (689221) | more than 11 years ago | (#6720043)

Public advocacy for U.S. member interests, and for women in engineering and ethics

I think I can speak for us all, when I say that I also advocate for women in engineering. Especially attractive ones.

Re:Ha (1)

kaltkalt (620110) | more than 11 years ago | (#6720011)

Isn't anthropic thinking wonderful? :)

Nanopower (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6719729)

Nano technology to solve the energy crisis. Nanobots to deliver power where needed. Nanobots to design power grids on the fly and stuff like that. Sh*t people invest in my idea... send me money. Alright that's my 2c.

WTF (1, Insightful)

Anonymous Coward | more than 11 years ago | (#6719737)

WTF are "power electronics"?

Couldn't you at elast have given us some tiny hint, so that upon clicking your links we'd be going into the articles having some vague clue how to parse your summary?

Re:WTF (2, Informative)

bersl2 (689221) | more than 11 years ago | (#6720018)

IIRC, power electronics deals with the regulation thereof. A good example is the creation of a power supply which turns AC into a smooth DC. Look here [pels.org] .

Grabby headlines (3, Funny)

Faust7 (314817) | more than 11 years ago | (#6719747)

Steady As She Blows

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

Re:Grabby headlines (0)

Anonymous Coward | more than 11 years ago | (#6719769)

Looks like they're hard-up for readers

Yeah, they're hard-up for readers who aren't 15 year old immature Lunix hippies.

Re:Grabby headlines (1)

Cyno01 (573917) | more than 11 years ago | (#6719940)

heh, you said hard-up

hmmmm (-1, Offtopic)

squarefish (561836) | more than 11 years ago | (#6719766)

power, powered by more power....

.....

geeeee

let me think about this!!!

Simple Tweakage (3, Interesting)

EvilTwinSkippy (112490) | more than 11 years ago | (#6719782)

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 (0)

Anonymous Coward | more than 11 years ago | (#6719879)

If you only knew how many power plants aren't being used across Canada. What a waste, and it makes no sense.

Re:Simple Tweakage (4, Interesting)

evilWurst (96042) | more than 11 years ago | (#6719955)

"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.

Simple Tweakage-As the coil turns. (0)

Anonymous Coward | more than 11 years ago | (#6720007)

That's one way. I remember when superconduction came on the scene. One of the ideas was an underground superconduction coil. Basically an induction coil, on a much bigger scale.

Re:Simple Tweakage (0, Offtopic)

BigBadBri (595126) | more than 11 years ago | (#6719990)

a Taurus with a 3.6 liter V6

That has to be the ultimate insult.

Couldn't think of a proper car to beat a Honda, or were you just going for the worst case scenario?

There are more important things than straight line speed, but I can't think of them right now.

Re:Simple Tweakage (2, Interesting)

Anonymous Coward | more than 11 years ago | (#6720006)

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 (5, Interesting)

csbruce (39509) | more than 11 years ago | (#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.

Here's my 2 cents (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6719785)

Fucking posers. Y'all know shit about IT. Come knockin' on my door the day you'll hack the Pentagon, and maybe we'll discuss. Until then, y'all can suck my motherfuckin' dick.

Douche Baggy Bagg 4 Prez, biatch ! [geocities.com]

Re:Here's my 2 cents (0)

Anonymous Coward | more than 11 years ago | (#6719836)

We know shit about IT? This from a troll that thinks Information Technology is about hacking the Pentagon, and says "Y'all"

Do you think IT is some new invention that some guy made and over-hyped.

Or is IT you're complete lack of intelligence?

Maybe IT is your complete lack of a life. So bad that you spend your free time insulting a generalization of people you've never even met.


Ok, I've spent enough of my time insulting a troll.

j00r gr4mm4R s0x0rZ (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6719882)

Me made yo mamma do IT, coz yo mamma's da shit. Maybe she be tellin' ya someday :

Momma was a hoe, I was weekend pussy
I had you to keep the nigga, it didn't work out
that's why he ain't here - but he a good nigga
cause he take care of his REAL family
I was just a dumb bitch, tryin to keep, a nigga that I wanted

Better recognize, BIATCH !

Re:Here's my 2 cents (0)

Anonymous Coward | more than 11 years ago | (#6719920)

Hacking the Pentagon is all about information technology you fuckin' moron.

Management *is* key... (5, Interesting)

neiffer (698776) | more than 11 years ago | (#6719787)

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... (5, Insightful)

Anonymous Coward | more than 11 years ago | (#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

Re:Management *is* key... (1)

DAldredge (2353) | more than 11 years ago | (#6719886)

Well, Ogg the CaveMan would fully support the rocks tied to ropes method!!! At least when he wasn't smashing Open Source CDs...

Re:Management *is* key... (2, Insightful)

neiffer (698776) | more than 11 years ago | (#6719893)

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.

Re:Management *is* key... (2, Insightful)

LostCluster (625375) | more than 11 years ago | (#6719930)

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.

Re:Management *is* key... (1)

neiffer (698776) | more than 11 years ago | (#6719942)

So true. We've been looking for that battery since the development of power sources like dams. We rely on dams here a lot (I live in Montana) and we use only a fraction what it can product. We can send power elsewhere (cough...California) but we lose a lot in the transfer.

Re:Management *is* key... (0)

Anonymous Coward | more than 11 years ago | (#6719977)

> ...goo goo gah joob.

Guys, this is a reference to a pr0n movie!

I can't believe you didn't catch such an obvious troll.

Re:Management *is* key... (1)

neiffer (698776) | more than 11 years ago | (#6720015)

It's a reference to a Beatles song, dumb ass.

Re:Management *is* key... (1)

BigBadBri (595126) | more than 11 years ago | (#6719999)

No - the key is to have a decent method of yak-frighening, allowing the production of fuel on demand.

Interesting Article (3, Funny)

notque (636838) | more than 11 years ago | (#6719789)

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?..

Re:Interesting Article (1)

LostCluster (625375) | more than 11 years ago | (#6719948)

Uhm... the price of oil might be a pretty good indicator...

Mirrored without the troll... Enjoy (0)

Anonymous Coward | more than 11 years ago | (#6719793)

Steady As She Blows

Power electronics and exotic energy storage devices are making wind power steady enough to compete with conventional electricity sources

By Peter Fairley

In this season of discontent in the electricity business, only wind power seems to stand out as a global success story. While petroleum prices were convulsing in response to war and labor strife, and nuclear plants were stoking controversy in the Middle East and Asia, wind turbines were quietly becoming the fastest-growing energy source in the world. They now provide more than 31 000 MW of power, a total that has swelled by almost 30 percent in scarcely a year's time and that keeps more than 200 million tons of carbon dioxide out of the atmosphere every year. Wind power's ascendance has been so stunning that advocates are now rallying around an idea that would have seemed preposterous just a couple of years ago: that the wind could supply 12 percent of the world's electrical demand by 2020.

Impressive as the gains have been, it isn't quite clear yet that the wind can blow away the developed world's fossil-fuel dependence. One of the most important reasons is that clean, renewable wind power comes with a serious hitch: while conventional power plants yield a steady stream of electricity, wind turbines often ply turbulent gusts and therefore spit out an irregular stream of electricity that is tough for power grids to swallow.

Now, though, high-tech solutions are at hand. Systems based on advanced power-electronics and energy storage devices are massaging and managing power flows from wind turbines, enabling them to contribute mightily to electricity grids without putting those grids at risk. Not only are the technologies making wind power more palatable to grid operators, they are even making it possible for engineers to finally harness wind energy's tremendous potential in wind-swept, remote locales.

Perhaps nowhere is this potential so evident as in the state of Hawaii, whose isolated power grids could not otherwise risk taking full advantage of the archipelago's abundant, renewable resource. In fact, with its lush, endless trade winds and growing commitment to wind power, Hawaii's Big Island is emerging as a laboratory of the future of the technology. As wind power becomes a steadier and more reliable resource, it could help wean power producers all over the state from their dependence on costly imported oil.

But, for now, says Karl Stahlkopf, chief technology officer at Hawaii Electric Co., in Honolulu, even the existing wind farms on the Big Island--putting out just
10 MW, the equivalent of four state-of-the-art wind turbines--make grid controllers hop on days when the palm fronds fly.

The utility and its contractors plan to build what Stahlkopf calls an "electronic shock absorber" to buffer the island's power grids against the wind's worst behavior. It's a development that engineers elsewhere are following closely.

The reason is that the solutions to integrating modest levels of wind power on small, isolated grids today may foreshadow the installation of truly large-scale wind power in mainland networks five or 10 years from now. "What's happening in the Hawaiian Islands is a peek at the future," says Bob Zavadil, an expert on wind power at the Arlington, Va.-based power systems analysis firm Electrotek Concepts Inc. "They're on the leading edge." And that's true not only of the technology but also of the new legal and regulatory conventions between utilities and independent power producers that will be needed before wind energy can truly thrive.

Reactive Power 101
Back on the mainland, wind farms have grown to dozens of turbines and hundreds of megawatts--rivaling the size of conventional power plants. To pave the way for installations like those, engineers had to grapple with the tendency of wind turbines to introduce voltage instability into electrical grids. That tendency follows from the intermittent nature of wind-generated electricity, which waxes and wanes in irregular episodes unrelated to the predictable daily ebb and flow of consumer demand.

To understand the instability issue--and its solution--you'll need a few basics on the nature of power flows on utility grids. First, recall that these flows consist of both active and reactive power. The difference between them arises from the fact that the wave of alternating current on a power grid almost always leads or lags the voltage wave. In short, inductors, such as the coils in motors or transformers, cause current to lag voltage; capacitors cause current to lead voltage.

Active power is the familiar watts consumed by light bulbs and toasters; it is the product of voltage and the component of current that is in phase with the voltage. Reactive power, measured in volt-amperes reactive, or VARs, is the product of voltage and the out-of-phase component of alternating current. This out-of-phase power is consumed by energetic electric or magnetic fields--for example, in coils in inductive loads, such as motors, and also in the utility's own transformers. Transmission lines themselves are also inductive. In the case of wind-generated power, this line inductance can be a critical factor, because the turbines are usually far from population centers, strung out across windy plains or even areas out at sea.

Utilities have to pay close attention to reactive power because it determines, along with active power, how the voltage declines, or "sags," on an electric network. Utilities must keep voltages very close to rated values because when they fall too low, motors and other inductive loads draw too much current, overheating the equipment and possibly damaging it and other utility gear as well.

Declining voltage on a network is a function of the consumption of both active and reactive power. In other words, if a big load consumes lots of reactive power, it will cause the voltage to sag intolerably unless that reactive load is adequately compensated for. Because these reactive loads are almost always inductive, causing current to lag voltage, utilities must feed them with reactive power in which the reverse is true--with current that leads voltage.

For this they have several options. They can supply reactive power right from the generators themselves, by producing current waveforms that lead voltage. They can also install banks of capacitors close to big inductive loads. As the load rises, relays switch on the capacitor banks to add reactive power.

So what does all this have to do with wind power? Many modern wind turbines generate electricity with an induction generator, also known as an asynchronous generator. Conventional, fossil-fueled power plants, on the other hand, are built around synchronous generators. There's a big difference between the two kinds of generators: a synchronous unit can provide both active and reactive power, as noted above. An induction generator, on the other hand, provides active power but consumes reactive power. This characteristic, coupled with the wind's intermittence, plays havoc with utility grids.

"As the wind comes and goes, the voltage goes down and up right along with it," explains Bud Kehrli, manager of transmission and distribution planning for the power equipment maker American Superconductor Corp., in Middleton, Wis. You could handle the problem by switching capacitor banks in or out, but it takes lots of nimble switching to keep up with the ever-varying gusts. And switching a big block of capacitance in or out can swing the voltage up or down a few percent or more, a variation that is felt as an abrupt change in torque on the turbines' gearboxes. Slamming a gearbox like that repeatedly is a bad idea because it soon wears it out, and replacing one costs about US $200 000 in parts, labor, and other expenses.

Semiconductor solution
These are exactly the problems that power semiconductors are solving from Andalucia to Abilene. Consider the Foote Creek Rim wind project in southeastern Wyoming, one of the biggest in the United States. The installation, which feeds grids operated by the utility giant PacifiCorp, in Portland, Ore., includes 183 induction turbines installed over the last four years, which generate up to 135 MW--enough for 25 000 households.

In choppy winds, the switching capacitor banks were often a step behind the wind, leaving an excess or shortage of reactive power on the local 230-kV transmission line, a major conduit through which PacifiCorp moves power from large coal-fired plants in Wyoming to customers in six western states. As a result, voltage on the line would spike up or down by as much as 5 or 6 percent.

Until this year, PacifiCorp stabilized those lines by brute force: it simply idled dozens of wind turbines at Foote Creek, throwing away cheap, clean energy in order to ship its coal-fired power. But this past February, the company turned to power electronics for a more satisfying solution, installing a $1.5 million system of silicon switches designed and built by American Superconductor to dynamically adjust reactive power at Foote Creek.

The new system is called D-VAR, for dynamic volt-amperes reactive. It can provide up to 8 mega-VARs of reactive power continuously (or 24 MVARs momentarily). Best of all, it can inject this reactive power in increments of as little as 0.027 MVAR, and it can turn on a dime, going from, say, -8 MVARs to +8 MVARs in less than one electrical cycle, or 1/60 of a second. At Foote Creek, the D-VAR system also controls nine banks of capacitors, totaling 50 MVARs, switching these capacitors on and off and interjecting its own MVARs as necessary to provide a smooth and essentially continuous range of reactive compensation up to 58 MVARs [see illustration].

The secret of the D-VAR's success is the insulated-gate bipolar transistor (IGBT), which was invented at about the same time, 20 years ago, at General Electric Co. (Fairfield, Conn.) and at the former RCA Corp. IGBTs are like high-power cousins of the transistors in your computer or cellphone, and they function in the D-VAR system as rapid power valves, opening and closing many times per cycle to produce an alternating current waveform that mimics the effects of an ultraprecise, adjustable capacitor bank.

Inside the D-VAR is a direct current bus whose voltage of 750 V is maintained by transforming and rectifying voltage from the external bus fed by the wind turbines. The IGBTs, controlled by microprocessors, switch between the dc bus and the external bus at a pace fast enough to establish a carrier frequency at 3 kHz.

Switching in elaborate, precisely timed patterns, the IGBTs produce sine waves at 60 Hz by means of a standard technique called pulse-width modulation. The longer the IGBT switches dwell in the "on" state, the closer the sine wave gets to an amplitude peak. And the longer the IGBTs are off, the closer the wave is to zero amplitude. Before the sine waves are transmitted on to the external bus, they are filtered to remove the 3-kHz carrier wave, producing smooth 60-Hz waves.

By adjusting the on-off patterns of the IGBTs, the system controller can make the current sine wave lead or lag the voltage by any degree desired. However, D-VAR is set up so that it produces a waveform in which the current sine wave leads the voltage sine wave by 90 degrees, thus mimicking the effects of a capacitor bank. To vary the amount of reactive power the D-VAR is supplying--the "capacitance," you could call it--the controller simply adjusts the amplitude of the current.

Built-in chips
Given the commitment to induction generators on the part of heavy hitters like Japan's Mitsubishi Heavy Industries Ltd. (Tokyo), substations will provide a ready U.S. market for IGBTs and other power semiconductors from American Superconductor and rivals ABB Ltd. (Zurich) and Siemens AG (Munich) for years to come.

But in Europe, wind farm operators are taking a different approach to harnessing the wind--and to handling wind turbines' thirst for reactive power.

The impetus had nothing to do with reactive power. Developers were just trying to reduce the mechanical strain on large, fixed-speed turbines, whose rotors can stretch wider than the wingspan of a jumbo jet. Their solution involves building the silicon switches right into the turbine.

What makes it all possible is a shift in the technology of the turbines themselves: instead of induction generators, wind farm operators are now more and more favoring variable-speed generators that can absorb the force of a gust by speeding up. IGBTs and other power electronics in the turbine convert the variable-frequency "wild" ac from the generator into a steady sine wave synchronized to the grid (50 or 60 Hz, depending on where you are).

The beauty of this approach is that the same electronics can be programmed to simultaneously convert some of the turbine's active power into reactive power, as the network demands.

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.

Whether the power electronics are inside the turbine or in a substation, however, they are being used in new ways as wind farms become larger, more critical components of power systems. "Utilities are generally lining up to require that wind farms be able to provide dynamic reactive compensation, much as a conventional generator would be able to do," says American Superconductor's Kehrli.

That means being able to pitch in and help restore stability during a disturbance or some other crisis on the grid. In the past, when a generator failure or momentary short-circuit roiled a network, wind farms would automatically disconnect themselves. But now, most grid operators "want the turbines to ride through the disturbance," says Chuck McGowin, manager for wind power technology at the Electric Power Research Institute, a utility-funded R&D consortium based in Palo Alto, Calif. "It's a big shift."

The movement began in Europe, where, since this past January, for instance, the German utility E.ON Netz GmbH, in Bayreuth, has mandated a "ride-through" for the more than 5 GW of wind farms in its territory. That is, the turbines must continue to operate during "faults" when the voltage sags precipitously or the frequency deviates from 50 or 60 Hz. In recent months, utilities across the United States have begun to jump on the bandwagon. Suddenly, wind farms and turbine developers must alter their designs and operating procedures, particularly for voltage faults.

According to Craig Quist, a principal engineer at PacifiCorp, most wind turbines are programmed to disconnect themselves from the grid if voltage drops by 30 percent for 50 milliseconds--just a few cycles in the power wave. Once again, the ultimate solution may lie in power electronics. Substation semiconductors or bolstered on-board electronics can help wind farms ride through such events by generating extra reactive power to hold up the local line voltage.

No more trouble in paradise
Riding through voltage faults is just one of the challenges confronting Hawaii's Big Island, where Hawaii Electric and independent developers are considering proposals to boost wind power generation to 30-40 MW on a 150-MW grid. If it happens, the Big Island will be tapping wind power in the same proportion as Denmark, which gets about 20 percent of its power from the wind. But the Hawaiians will be doing it on a comparatively tiny grid lacking the stabilizing embrace of a continent-wide power grid.

The main problem is that bigger wind farms would amplify the impact of the wind gusts that are already taxing Hawaii's grid controllers. A 20-MW wind farm, for example, could surge by over 2 MW in just two seconds--much faster than the island's oil-fired generators could ramp down or up to balance supply and demand. Even momentary sporadic mismatches between supply and demand are unacceptable because they would alter frequency and voltage on the network, putting equipment at risk and causing lights to flicker.

To make sure that doesn't happen, Hawaii Electric airlifted Karl Stahlkopf to the island last year. He was a natural for the job, having led the development of a variety of power-electronics-based systems as vice president for power delivery and transmission at the Electric Power Research Institute. The giant shock absorber that Stahlkopf envisions for the Big Island would mediate between the power grid and the turbines, and it would combine power electronics with an advanced energy storage device, such as an ultracapacitor or a battery.

Slamming a gearbox repeatedly is a bad idea, because replacing one costs about $200 000

When the turbines are going full bore, Stahlkopf explains, the power electronics will divert some power into the storage system, drawing it out again when the wind dips. If the line voltage drops in a fault, the power electronics will dig deeper into the storage reservoir to generate reactive power and prop up the line. For the project, Hawaii Electric, the state, and the U.S. Department of Energy are now considering various storage technologies and capacities, and Stahlkopf reports that a shock-absorbing system could be on-line by the end of next year.

Meanwhile, wind farm developer Apollo Energy Corp. (Foster City, Calif.) is negotiating with Hawaii Electric to double its 9.8-MW Big Island wind farm at South Point [see photo] and it has proposed to connect the added capacity to the grid via a shock absorber similar in concept to Stahlkopf's.

The heart of Apollo's system would be 30 flow batteries from Menomonee Falls, Wis.-based ZBB Energy Corp. Flow batteries are a hybrid between electrochemical batteries and fuel cells. They use pumps to circulate a pair of electrolytes past an ion-exchange membrane similar to the ones employed in many fuel cells. Ions pass across the membrane from one electrolyte to the other to charge and discharge the battery.

The flow batteries in the system Apollo envisions could back up a 20-MW wind farm for several minutes. It wouldn't be cheap; building and operating the battery system could cost $1.8 million over its projected 17-year life span. But by keeping the wind farm going during the 200-plus hours each year when erratic winds would otherwise force operators to shut down some turbines, ZBB and its partners insist that the battery storage system would more than pay for itself--to the tune of $5.4 million over its lifetime.

Hawaii's wind dreamers are already looking beyond these grid-stabilizing systems to larger storage devices that could negate the ultimate challenge facing utilities with lots of wind power: keeping the juice flowing during the hours, days, or even weeks when the air is not. On average, wind turbines produce their rated power only 20 to 30 percent of the time. Really big storage systems, capable of storing at least tens of megawatt-hours of energy, could make wind power almost as "dispatchable" as that from a fossil-fuel plant.

Several years ago, Apollo Energy proposed installing a 10- to 11-MWh flow battery on the Big Island. And Stahlkopf has launched a research collaboration with local water authorities to test a lower-tech, but potentially more capacious, option. The idea is to piggyback on the Big Island's existing infrastructure of water mains and reservoirs to fashion a pumped-storage system that would push water to higher-altitude reservoirs when the wind was strong, and then let it fall through hydroelectric turbines to produce power when the air was still.

Rewriting the rule books
With power semiconductors and other technologies rapidly minimizing wind power's technical shortcomings, the hurdles increasingly seem to be contractual and regulatory. Utilities such as PacifiCorp, which had to foot the bill for the D-VAR installation that put an end to the voltage instabilities at Foote Creek, are rewriting their contracts to put the burden of integrating wind farms on their developers. "We got stung on the first wind farm, and we're not going to get stung again," declares PacifiCorp's Quist.

Lacking detailed standards for wind farm behavior, negotiations between utilities and wind farm developers can get ugly--even in paradise. On the Big Island, Hawaii Electric and Apollo Energy have been at odds for four years over Apollo's proposal to install newer, larger turbines at its wind farm. Its game plan to add the flow batteries didn't help matters. Apollo contends the battery system will make the wind installation a "firm" source of power--in other words, one that can dispatch power to help shore up the network in a crisis. State regulations generally specify that utilities must pay more for firm power.

Stahlkopf replies that Hawaii Electric isn't yet convinced that the flow battery will adequately protect the Big Island's grid. But he is confident that the two sides will find common ground in their negotiations.

Whatever agreement ultimately emerges, it is likely to push wind energy that much closer to the mainstream. And when regulations catch up to technology, wind energy--clean, renewable, and unaffected by geopolitical conflict--should come into its own as a steady energy source for these turbulent orgies.

MOD DOWN PARENT- TROLL! (0)

Anonymous Coward | more than 11 years ago | (#6719808)

In other words, if CmdrTaco dumps a big load and consumes lots of feces, it will cause the dig to sag intolerably

Wait a second! (1, Funny)

serial frame (236591) | more than 11 years ago | (#6719827)

Seems like the /. editors are on a bit of a power trip!

Re:Wait a second! (0)

Anonymous Coward | more than 11 years ago | (#6719894)

heh, power , get it?

Let me get this straight (0)

Anonymous Coward | more than 11 years ago | (#6719909)

YOU FAIL IT !

fuel cell (4, Interesting)

fishbert42 (588754) | more than 11 years ago | (#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 (1)

DAldredge (2353) | more than 11 years ago | (#6719877)

And what gas/liquid would power the fuel cell?

Re:fuel cell (1)

Edmund Blackadder (559735) | more than 11 years ago | (#6719910)

natural gas... or pure hydrogen if we can get the technology to produce it. But even if you use natural gas it is much more enviromentally friendly than burning the stuff.

Re:fuel cell (4, Insightful)

DrMrLordX (559371) | more than 11 years ago | (#6719925)

The idea would be to make them hydrogen fuel cells. You'd use inconsistant power sources(wind, solar) to generate electricity for the purpose of electrolysis. Split water into its component parts and you've got a nice and(somewhat) stable way to store all that energy you've converted into electricity via solar/wind generators without using expensive batteries, or at least not so many. Then distribute the hydrogen to fuel-cell owners and let them burn off hydrogen to produce local electricty on demand.

Of course there's going to be a lot of loss due to all the conversion steps(wind->electricity->hydrogen->electricity->me chanical energy) but it wouldn't be so bad once all the infrastructure necessary was in place.

The only concern I'd have is building a working facility to use electricity to seperate water that's reliant upon the inconsistant power levels that solar and wind generators would provide. This would almost seem to be more useful for solar facilities. Sunlight is a bit more predictable than wind, or so I would think.

Um, anyone know what happened to polar-solar.com? Was that a hoax or did they just go belly-up due to lack of interest?

Re:fuel cell (3, Insightful)

gordyf (23004) | more than 11 years ago | (#6720014)

This would require that not only you had enough wind/solar/etc power to run your home during the day, but also to split water during the day, enough of it to run your home at night.

Would it not be easier to have enough wind/solar/etc power to run your home during the day, selling the excess to the power company and then pulling from the grid at night? You wouldn't have the up-front cost of electrolysis/fuel cell equipment, and you wouldn't pay for the power at night since you were being paid all during the day (at peak rates, even).

Re:fuel cell (3, Interesting)

tupps (43964) | more than 11 years ago | (#6720047)

What about something like these: http://www.me.washington.edu/~malte/engr342/homewo rk/wq2001_homework/342.01.HW7s_tower.pdf Basic principal is you heat molten salt and then derive power by using the heated molten salt to generate steam (for a turbine). You therefore get cheap easy storage of the power and you can generate different levels of power from the system as is needed.

Re:fuel cell (1)

sys$manager (25156) | more than 11 years ago | (#6719978)

There are Direct Methanol Fuel Cells out now too. Methanol is poisonous but it's simple to handle.

fuel cell-Trash treasure. (0)

Anonymous Coward | more than 11 years ago | (#6720036)

Don't forget that technology mentioned awhile back on "/." about converting trash to a fuel source.

Re:fuel cell (5, Insightful)

michael_cain (66650) | more than 11 years ago | (#6720027)

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.

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

Anonymous Coward | more than 11 years ago | (#6719864)

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 (3, Insightful)

Anonymous Coward | more than 11 years ago | (#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 (3, Insightful)

LostCluster (625375) | more than 11 years ago | (#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.

One of the issues that stops wind power. (4, Interesting)

DAldredge (2353) | more than 11 years ago | (#6719870)

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...

Offshore! Problem solved! (0)

Anonymous Coward | more than 11 years ago | (#6719898)

http://www.offshorewindfarms.co.uk/

Check this one out - just put them on old oil rigs, or build new platforms, also , Isaw something recently about putting them underwater.

Re:One of the issues that stops wind power. (1)

Edmund Blackadder (559735) | more than 11 years ago | (#6719969)

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.

Conservatives... (1)

starcraftsicko (647070) | more than 11 years ago | (#6720056)

aren't big on having coal plants in their back yard but, being a "conservative" myself, I wish that that power plant that was just built in my town was nuclear rather than a polluting gas plant. Nuclear, unlike all types of fossil fuel plants, does not release pollution into the environment when it is run correctly. But it seems that while rich environmentalists will file lawsuit after injunction after restraining order after lawsuit to prevent the construction of relatively clean energy, thew will (in fact they DID) nothing whatsoever to prevent, or significantly delay, the construction or certification of the "new" gas pollution plant. Go figure.

Switch to DC (1, Flamebait)

amorsen (7485) | more than 11 years ago | (#6719888)

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.

Re:Switch to DC (2, Interesting)

Edmund Blackadder (559735) | more than 11 years ago | (#6719937)

I know at least in mocroprocessors, wires that contain DC current that is always in one direction have a tendency to break...

Reason Why (1)

servoled (174239) | more than 11 years ago | (#6719961)

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.

Re:Switch to DC (1)

LostCluster (625375) | more than 11 years ago | (#6719941)

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.

Re:Switch to DC (1)

amorsen (7485) | more than 11 years ago | (#6720025)

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 (4, Interesting)

bluGill (862) | more than 11 years ago | (#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)

Re:Switch to DC (2)

von Moltke (224011) | more than 11 years ago | (#6720017)

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.

Re:Switch to DC (1)

MBCook (132727) | more than 11 years ago | (#6720028)

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.

Re:Switch to DC (4, Informative)

Victa (186697) | more than 11 years ago | (#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...

The Y2K bug... A flashback (4, Interesting)

RedCard (302122) | more than 11 years ago | (#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?

Re:The Y2K bug... A flashback (1)

bluGill (862) | more than 11 years ago | (#6720030)

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 with a fear mongering. Plenty of people made perdictions that had no basis in reality in effort to get money or fame. However there were very real problems out there, and they needed to be solved.

Re:The Y2K bug... A flashback (2, Insightful)

thebigmacd (545973) | more than 11 years ago | (#6720057)

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 (3, Informative)

segment (695309) | more than 11 years ago | (#6719934)


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

rock the volt (0, Redundant)

LostCluster (625375) | more than 11 years ago | (#6719975)

Yeah, but Gray Davis was the govenor in California who signed the deregulation bill that allowed Enron to manipulate the market in a house-of-cards sham.

The fact is, there's plenty of dumb regulatory moves on both sides to go around here. There all of the "rules" that apply to interconnecting grids are just industry standards, there's no punishment for breaking them. When such a weak regulatory system is in place, nothing much stops an Enron-like group of cheaters from stepping in and making a profit off of the mess at the expense of the public.

So, segment, you don't need to worry about off topic mods... it's -1 Flamebait that you posted. There's no room for either party to blame this on the other, they all failed and better get their act together and come up with something that keeps this from happening again.

Re:rock the volt (2, Funny)

CtrlPhreak (226872) | more than 11 years ago | (#6720053)

I hate how people use flaws on both sides of the political parties to somehow make their own party's flaws 'justified'. Everybody sucks, everybody makes mistakes, the whole two wrongs kinda deal. The fact is Davis sucks not just because he's a democrat but because he sucks. Also Bush sucks because he is a crappy president not just because he's a republican.

I've been lied to! (1)

zinac (684717) | more than 11 years ago | (#6719953)

Entergy here in north Louisiana told us that the power would NOT go out like it did in the North East, but just now, a power outage occured. .... makes you wonder.

Why not (2, Interesting)

BigBadBri (595126) | more than 11 years ago | (#6719968)

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.

How about spending less on weapons (-1, Flamebait)

Anonymous Coward | more than 11 years ago | (#6719974)


then maybe you wouldnt have these power problems

imagine how far 300 billion $ could go to achieve a grid that the world would be jealous of even cutting that in half would be a serious ochunk of change and you could buy your precious bombs the next year instead

looks like Bush and his buddy Ken Lay ripped you off the last few years

amazing how bad things have to get to incite change

In Other News.... (0, Troll)

servoled (174239) | more than 11 years ago | (#6719987)

Furtilizer Helps Grow Crops
Motor Oil Helps Reduce Friction in Engines
Story at 11

This is a DUPE! (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6720001)

You idiots. This is a dupe from yesterday or a few days ago. Funny the perspective though.

Nice to see our patent system working (4, Insightful)

Edmund Blackadder (559735) | more than 11 years ago | (#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.

Re:Nice to see our patent system working (1)

MBCook (132727) | more than 11 years ago | (#6720046)

Can't the government force patents to be available to anyone at atleast a reasonable price when it's in the public good? Even if not through regulation, what about the old "only companies that let others use their advanced turbine patents can get government contracts" kind of stuff. At some point the government should step in and deal with specific cases of "patent hording" when it's clearly in the public interest.

THIS JUST IN: Michael still sucks (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6720032)

Why did they let you back in? I thought they had kicked you out for good...

Doesn't quite ring true (5, Informative)

Willard B. Trophy (620813) | more than 11 years ago | (#6720040)

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 ...

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