oscillations on the power grid

Everyone who has every tried to build an amplifier knows how easy it is for
a circuit to oscillate when it isn't supposed to.

The descriptions of the power problems last week in the eastern US and
Canada sound to me like an oscillating mode across (or around) the entire
eastern power grid.    None of the descriptions of the problem, or possible
solutions, seem to mention this, though.   For a system that large and
complex, it isn't hard to believe that there are modes that no-one thought
about, or imagined, that, under unusual conditions happen to get excited.
Presumably there are systems to dampen out oscillations, but maybe this one
escaped.

If so, it would seem unfair to finger point at one power system or power
company, as the mode is one of the entire system.

I would be interested in constructive discussion of such systems.


-- glen

Hello Glen,
I agree with you in that stating one little thing caused the whole problem
is a bit misleading in that the grid must possess some form of achilles heel
or two or three. Our (North American) power grid is a lot more screwed up
than most ever know.

Several previous blackouts (US and Canada) are summarized in the following
link:

http://www.nerc.com/BlackoutTable.pdf

I think one of the major problems is that few want power generated near to
where it is being used. So we end up with a big web with a lot of energy
flowing over long distances. The half power distance (source to consumer)
I've seen cited is about 400 miles. I know that in New England, that permits
for the construction of new power plants havn't been issued since the
1960s/70s. All of the power plants that completed construction recently were
built using the old permits. So "new" plants arn't being built. Clearly
local energy production in highly populated areas is needed but not wanted
by the populace.

So we end up shipping power all over the place and since the topology is
more like a complete rather than a point to point network, it is easy to
imagine huge oscillations. We are all familiar with the problems of ground
loops and this grid has some similar types of problems. Some of the
utilities have reported that power flow in/out of their areas underwent a
complete change in direction. I think that this is a bit of a hint of an
oscillation. But maybe instead of oscillation, we can view the distance as a
wave travelling along and tripping out power plants and transmission lines.
At least the infrastructure protects itself. However when plants trip out,
it may take a day or more to restart. It is interesting to note that the
tripout wave (oscillation) took only around 9 seconds.

I think a good solution needs to power generated close to where it is
consumed. These areas can be thought of as cells where the power can only
enter or exit a cell at a limit number of points. The idea of local
generation/consumption should help decouple cells from each other.

Of course the economic structure of modern U.S. (Canadian too??) power
utilities is to have different owners for the components of the system. So
each company works to maximize its bit, instead of maximizing the whole
system.

A review of past blackouts shows that relatively minor disturbances in the
system can cause a major problem. The 3 day blackout of NYC back in the 70s
was precipatated by lightning stikes on a transmission line. The myriad
interconnections in the network are certain to create possibilities for
resonance. The causes of past wide area blackouts seem to support this
assertion. And since the conditions of the entire grid are highly variable,
I'm not sure if one can do an analysis to indicate it will be oscillation
free for disturbances injected anywhere in the system for all operating
configurations.

Another problem we have is political in that energy prices get fixed (from
the consumer's point of view) but the reseller gets stuck. The California
"rolling blackouts" were definitely caused by politics. The state
deregulated the industry, but leaving certain costs fixed. Thus power
companies ended up making money by reselling and transporting power, but
locally generated power was a financial loss. However Enron found a way to
export power from California to Nevada, and then bring it back into the
state at three times the cost.

Normally I'm a fan of free enterprise, but many recent examples of
deregulation have failed miserably. Not necessarily because of free
enterprise, but when businesses grow in one type of economy, they probably
end up very vunerable in other types of economies. And therefore when the
rules (one that constrain the operation of a business) are changed, we
expect the business to do worse. After all we only seem to deregulate
sucessful businesses, and it is always easier to ruin rather than improve a
business.

Clay
'


"Glen Herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
news:V490b.182193$Ho3.25305@sccrnsc03...
> Everyone who has every tried to build an amplifier knows how easy it is
for
> a circuit to oscillate when it isn't supposed to.
>
> The descriptions of the power problems last week in the eastern US and
> Canada sound to me like an oscillating mode across (or around) the entire
> eastern power grid.    None of the descriptions of the problem, or
possible
> solutions, seem to mention this, though.   For a system that large and
> complex, it isn't hard to believe that there are modes that no-one thought
> about, or imagined, that, under unusual conditions happen to get excited.
> Presumably there are systems to dampen out oscillations, but maybe this
one
> escaped.
>
> If so, it would seem unfair to finger point at one power system or power
> company, as the mode is one of the entire system.
>
> I would be interested in constructive discussion of such systems.
>
>
> -- glen
>
>

"Clay S. Turner" <physicsNOOOOSPPPPAMMMM@bellsouth.net> wrote in message
news:K3c0b.14569$sA4.4321@fe02.atl2.webusenet.com...
> Hello Glen,
> I agree with you in that stating one little thing caused the whole problem
> is a bit misleading in that the grid must possess some form of achilles
heel
> or two or three. Our (North American) power grid is a lot more screwed up
> than most ever know.
>
> Several previous blackouts (US and Canada) are summarized in the following
> link:
>
> http://www.nerc.com/BlackoutTable.pdf
>
> I think one of the major problems is that few want power generated near to
> where it is being used. So we end up with a big web with a lot of energy
> flowing over long distances. The half power distance (source to consumer)
> I've seen cited is about 400 miles. I know that in New England, that
permits
> for the construction of new power plants havn't been issued since the
> 1960s/70s. All of the power plants that completed construction recently
were
> built using the old permits. So "new" plants arn't being built. Clearly
> local energy production in highly populated areas is needed but not wanted
> by the populace.

My (simple) understanding of the system, though, is that power can be bought
and sold long distance, so that power may be sent much farther than the 400
miles.

> So we end up shipping power all over the place and since the topology is
> more like a complete rather than a point to point network, it is easy to
> imagine huge oscillations. We are all familiar with the problems of ground
> loops and this grid has some similar types of problems. Some of the
> utilities have reported that power flow in/out of their areas underwent a
> complete change in direction. I think that this is a bit of a hint of an
> oscillation. But maybe instead of oscillation, we can view the distance as
a
> wave travelling along and tripping out power plants and transmission
lines.
> At least the infrastructure protects itself. However when plants trip out,
> it may take a day or more to restart. It is interesting to note that the
> tripout wave (oscillation) took only around 9 seconds.

Actually going out took 9 seconds, but it seems that the beginnings of
oscillation were noticed up to four hours earlier.  The system slowly
approached the instability.

(snip)

-- glen

Glen Herrmannsfeldt wrote:
> 
> Everyone who has every tried to build an amplifier knows how easy it is for
> a circuit to oscillate when it isn't supposed to.
> 
> The descriptions of the power problems last week in the eastern US and
> Canada sound to me like an oscillating mode across (or around) the entire
> eastern power grid.    None of the descriptions of the problem, or possible
> solutions, seem to mention this, though.   For a system that large and
> complex, it isn't hard to believe that there are modes that no-one thought
> about, or imagined, that, under unusual conditions happen to get excited.
> Presumably there are systems to dampen out oscillations, but maybe this one
> escaped.
> 
> If so, it would seem unfair to finger point at one power system or power
> company, as the mode is one of the entire system.
> 
> I would be interested in constructive discussion of such systems.
> 
> -- glen

There was about an hour of trouble local to Ohio before the nine seconds
-- 540 cycles -- it took for trouble to spread to the far side of the
affected area. One system operator I met socially a few weeks ago told
me that he had been pleading for regulations to put into place measures
that would, if I understood him, would have kept this outage local.
(Legislation do do that has been pending in Congress for years, but
Republicans linked it with permission to open new oil fields in Alaskan
wildlife preserves, and Democrats won't allow it to pass with that rider
in place.) Right now, compliance with robustness recommendations is
voluntary, and system managers have to choose between profitability and
reliability. My informant pointed out that since each manager's
performance is measured against the others', if one of his colleagues
doesn't comply, none of the rest can afford to. Unregulated industries
are quite properly responsible to their stockholders. It takes
regulation by agencies free of political pressure to redirect some of
that responsibility toward society at large.

It was strange to hear that line of reasoning from one who could be
described as a captain of industry, but he's a realist with experience
and a conscience.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

Glen Herrmannsfeldt wrote:
> 
> Everyone who has every tried to build an amplifier knows how easy it is for
> a circuit to oscillate when it isn't supposed to.
> 
> The descriptions of the power problems last week in the eastern US and
> Canada sound to me like an oscillating mode across (or around) the entire
> eastern power grid.    None of the descriptions of the problem, or possible
> solutions, seem to mention this, though.   For a system that large and
> complex, it isn't hard to believe that there are modes that no-one thought
> about, or imagined, that, under unusual conditions happen to get excited.
> Presumably there are systems to dampen out oscillations, but maybe this one
> escaped.
> 
> If so, it would seem unfair to finger point at one power system or power
> company, as the mode is one of the entire system.
> 
> I would be interested in constructive discussion of such systems.
> 
> -- glen

There was about an hour of trouble local to Ohio before the nine seconds
-- 540 cycles -- it took for trouble to spread to the far side of the
affected area. One system operator I met socially a few weeks ago told
me that he had been pleading for regulations to put into place measures
that would, if I understood him, have kept this outage local.* Right
now, compliance with robustness recommendations is voluntary, and system
managers have to choose between profitability and reliability. My
informant pointed out that since each manager's performance is measured
against the others', if one of his colleagues doesn't comply, none of
the rest can afford to. Unregulated industries are quite properly
responsible to their stockholders. It takes regulation by agencies free
of political pressure to redirect some of that responsibility toward
society at large.

It was strange to hear that line of reasoning from one who could be
described as a captain of industry, but he's a realist with experience
and a conscience.

Jerry
______________________________________
* Legislation do that has been pending in Congress for years, but
Republicans linked it with permission to open new oil fields in Alaskan
wildlife preserves, and Democrats won't allow it to pass with that rider
in place.
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

"Clay S. Turner" <physicsNOOOOSPPPPAMMMM@bellsouth.net> wrote in message news:<K3c0b.14569$sA4.4321@fe02.atl2.webusenet.com>...
> Another problem we have is political in that energy prices get fixed (from
> the consumer's point of view) but the reseller gets stuck. The California
> "rolling blackouts" were definitely caused by politics

Over here (at least in Norway, perhaps also in other scandinavian countries) 
there have been huge complications after deregulating (transferring 
ownership from the government to the stock market) of the power producing 
facilities.

Norwegian power plants have in general been owned by a government agency, 
with supplemental power plants for industry being owned by local producers. 
A few years ago the government agency was privatized, and the focus turned 
from providing sufficent power to making money on selling power. 

The power grid is based on hydropower plants. There are no nuclear 
facilities and no fossile fuel facilities, which means the grid isn't very 
dynamic, production wise, as all power plant are very expencive and need 
to generate income, and the power grid depends on climate.

The main consumption in private households is during winter. The main 
accumulation of water in the dams are during thaw in spring, and to some 
extent during autumn rain. However, after the deregulation of the market, 
power producers are accused of letting the power plants run at high 
production (thus draining magazines) during summer and sell the power in 
continental Europe. Which means that the magazines are low when winter 
comes and may run dry before spring. Which means that not only does the 
price to the consumer skyrocket; there may not be enough power to cover 
the supply. With no alternative source of power... well, we're stuck. 
 
Of course, there is the question of importing power. However, the transfer 
lines from continental Europe are running at max capacity. And the 
responsibility of providing transfer capacity lies with -- you guessed it --
the very agency that used to be govrnment but now has as its main interest 
to provide the shareholders with max profit. 

All in all, the consumers are essentially living at the mercy of the power 
companies. As long as the companies' main interest and responsibility lies 
in making the most profit for the shareholders, they can do what they want 
as long as the country doesn't sufficate. There appears to be no governemtal 
instruments left to ensure ample supply of power, adequate reserve lines 
to abroad or otherwise secure national interests. There have been some 
talk about building power facilities based on Liquid Natural Gas(?) to 
cover the worst crises, but such facilities are higly controversial since 
they would emit various byproducts (mainly CO2), even in very low quantities 
compared to oil or coal-based facilities.

I guess this amounts to a discussion about how much basic infrastructure 
should be provided by the government. I think the free enterprise only 
works in a market above a certain size, and when the goods and comodities 
are in ample supply. It appears as if those prerequisites are lacking in 
the Norwegian power market.

Rune

Rune Allnor wrote:
> 
  ...
> 
> Of course, there is the question of importing power. However, the transfer
> lines from continental Europe are running at max capacity. And the
> responsibility of providing transfer capacity lies with -- you guessed it --
> the very agency that used to be govrnment but now has as its main interest
> to provide the shareholders with max profit.
> 
> All in all, the consumers are essentially living at the mercy of the power
> companies. As long as the companies' main interest and responsibility lies
> in making the most profit for the shareholders, they can do what they want
> as long as the country doesn't sufficate. There appears to be no governemtal
> instruments left to ensure ample supply of power, adequate reserve lines
> to abroad or otherwise secure national interests. There have been some
> talk about building power facilities based on Liquid Natural Gas(?) to
> cover the worst crises, but such facilities are higly controversial since
> they would emit various byproducts (mainly CO2), even in very low quantities
> compared to oil or coal-based facilities.
> 
> I guess this amounts to a discussion about how much basic infrastructure
> should be provided by the government. I think the free enterprise only
> works in a market above a certain size, and when the goods and comodities
> are in ample supply. It appears as if those prerequisites are lacking in
> the Norwegian power market.
> 
> Rune

Every company is duty bound to maximize the benefit that its owners
receive to the extent that the law allows. Your utilities are acting
responsibly according to their present charter. There is a problem, but
it is with the charter, not with management. To some extent, laws can
mitigate the problem, but while the charter remains as it is, it will be
the managers' duty to circumvent the law in every allowable way. They
know more about generation and distribution than those who write the
laws, so the outcome of the battle of wits is clear.

Many will argue that public ownership -- the charter that serves the
public -- is wasteful. Counterexamples are easy to find. I have worked
for RCA, General Electric, and Siemens, and served on the board of a
seven-municipality sewerage authority owned and financed by my
neighbors. If waste at the Authority* approached the best of the
corporations that I was aware of (I knew all the goings on at the
Authority but only a trifle of what went on where I worked), I would
likely have gone to jail. One can squander private money with impunity.

Jerry
___________________________________
* http://www.sbrsa.org/index_1.html is the beginning of a web presence
that clearly no money has been wasted on. (I may volunteer to fix and
expand it.) I was there during the original construction, and I just
returned from a meeting about modifying the members' debt-service
obligations. It's a lean operation as entities with that gross go.
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On Mon, 18 Aug 2003 18:20:01 -0400, "Clay S. Turner"
<physicsNOOOOSPPPPAMMMM@bellsouth.net> wrote:

>Hello Glen,
>I agree with you in that stating one little thing caused the whole problem
>is a bit misleading in that the grid must possess some form of achilles heel
>or two or three. Our (North American) power grid is a lot more screwed up
>than most ever know.
>
>Several previous blackouts (US and Canada) are summarized in the following
>link:
>
>http://www.nerc.com/BlackoutTable.pdf
>
>I think one of the major problems is that few want power generated near to
>where it is being used. So we end up with a big web with a lot of energy
>flowing over long distances. The half power distance (source to consumer)
>I've seen cited is about 400 miles. I know that in New England, that permits
>for the construction of new power plants havn't been issued since the
>1960s/70s. All of the power plants that completed construction recently were
>built using the old permits. So "new" plants arn't being built. Clearly
>local energy production in highly populated areas is needed but not wanted
>by the populace.
>
>So we end up shipping power all over the place and since the topology is
>more like a complete rather than a point to point network, it is easy to
>imagine huge oscillations. We are all familiar with the problems of ground
>loops and this grid has some similar types of problems. Some of the
>utilities have reported that power flow in/out of their areas underwent a
>complete change in direction. I think that this is a bit of a hint of an
>oscillation. But maybe instead of oscillation, we can view the distance as a
>wave travelling along and tripping out power plants and transmission lines.
>At least the infrastructure protects itself. However when plants trip out,
>it may take a day or more to restart. It is interesting to note that the
>tripout wave (oscillation) took only around 9 seconds.

I think another suitable model for what happens is impedance mismatch
on a comm transmission line.  When one of those breakers pops or some
failure happens (say, in a substation or something) that changes the
apparent impedance to the line at high load, a lot of power suddenly
gets reflected back in the direction from whence it came.   This may
account for the explanations of power reversing direction (I'm not
sure why that would happen otherwise, but I'm not much of a power
engineer).

>I think a good solution needs to power generated close to where it is
>consumed. These areas can be thought of as cells where the power can only
>enter or exit a cell at a limit number of points. The idea of local
>generation/consumption should help decouple cells from each other.

Last night CNN had a report on many high rises in the east (NY
particularly) that have disconnected themselves from the power grid
and generate their own power.  One residential high rise association
has had their own generators since 1986 and estimates that they're
saving a half-million dollars a year doing so, and weren't affected by
this blackout (obviously).

>Of course the economic structure of modern U.S. (Canadian too??) power
>utilities is to have different owners for the components of the system. So
>each company works to maximize its bit, instead of maximizing the whole
>system.
>
>A review of past blackouts shows that relatively minor disturbances in the
>system can cause a major problem. The 3 day blackout of NYC back in the 70s
>was precipatated by lightning stikes on a transmission line. The myriad
>interconnections in the network are certain to create possibilities for
>resonance. The causes of past wide area blackouts seem to support this
>assertion. And since the conditions of the entire grid are highly variable,
>I'm not sure if one can do an analysis to indicate it will be oscillation
>free for disturbances injected anywhere in the system for all operating
>configurations.

I think a major part of the problem is that the system was engineered
piecemeal and not as the system that it is.  This is just the reality
of the evolution of the thing, but I think it is largely responsible
for why it is so difficult to manage.  As you point out, since the
pieces of the system are still independant there isn't a means, beyond
legislation, to apply any total system engineering solutions.  I'm not
sure that that's the sort of thing that should come from legislation,
anyway, an industry consortium would probably be a better way to
approach it, IMHO. 

>Another problem we have is political in that energy prices get fixed (from
>the consumer's point of view) but the reseller gets stuck. The California
>"rolling blackouts" were definitely caused by politics. The state
>deregulated the industry, but leaving certain costs fixed. Thus power
>companies ended up making money by reselling and transporting power, but
>locally generated power was a financial loss. However Enron found a way to
>export power from California to Nevada, and then bring it back into the
>state at three times the cost.

The price fixing doesn't happen everywhere, and it isn't always
relevant.  In AZ we have a few local power producers that have more or
less always had some competitive mechanisms applied to them.  Of the
two largest, one is a municipality and one is the usual corporate
enterprise.  Oddly enough, the corporate enterprise has been steadily
reducing consumer electric rates for about ten years until only very
recently (like within the last month).  Our power here is pretty
reliable but we're not subject to a lot of the weather disturbances
that some places are.

>Normally I'm a fan of free enterprise, but many recent examples of
>deregulation have failed miserably. Not necessarily because of free
>enterprise, but when businesses grow in one type of economy, they probably
>end up very vunerable in other types of economies. And therefore when the
>rules (one that constrain the operation of a business) are changed, we
>expect the business to do worse. After all we only seem to deregulate
>sucessful businesses, and it is always easier to ruin rather than improve a
>business.
>
>Clay

Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

eric.jacobsen@ieee.org (Eric Jacobsen) wrote in message news:<3f427bc1.613763997@news.west.earthlink.net>...
>
snip
> 
> I think another suitable model for what happens is impedance mismatch
> on a comm transmission line.  When one of those breakers pops or some
> failure happens (say, in a substation or something) that changes the
> apparent impedance to the line at high load, a lot of power suddenly
> gets reflected back in the direction from whence it came.   This may
> account for the explanations of power reversing direction (I'm not
> sure why that would happen otherwise, but I'm not much of a power
> engineer).

Last year we had a large blackout in Denmark, I'm not sure of the details
but AFAIR a delay in the network between some safety systems, tricked it 
into believing something was wrong and it shutdown the connection to 
the rest of europe and then the powerplans just started shutting down. 
Don't know if they somehow depend on a reference?, connecting grids 
that aren't in phase would probably not be pretty :)   

> 
> >I think a good solution needs to power generated close to where it is
> >consumed. These areas can be thought of as cells where the power can only
> >enter or exit a cell at a limit number of points. The idea of local
> >generation/consumption should help decouple cells from each other.
> 
> Last night CNN had a report on many high rises in the east (NY
> particularly) that have disconnected themselves from the power grid
> and generate their own power.  One residential high rise association
> has had their own generators since 1986 and estimates that they're
> saving a half-million dollars a year doing so, and weren't affected by
> this blackout (obviously).

but might present another problem, if you have plenty of "clean" energy
somewhere e.g. hydropower, it might be better to distribute that, than
have a lot of small plans burning oil or coal, and I think that the bigger 
plans will generally have better efficiency and filters. 
 
> 
snip

The last week has been a bit of a wakeup call, (I hope :)) in between 
all the talk about blackout people here in Phoenix spend hours 
in line at gas stations to buy gas 3$/gallon because of a broken 
pipeline. 

a couple of $ more and it'll reach danish prices ;)
  

-Lasse

langwadt@ieee.org (Lasse Langwadt Christensen) wrote in message news:<dd93222a.0308192031.1e2f359@posting.google.com>...
> eric.jacobsen@ieee.org (Eric Jacobsen) wrote in message news:<3f427bc1.613763997@news.west.earthlink.net>...
 
> if you have plenty of "clean" energy
> somewhere e.g. hydropower, it might be better to distribute that

That's the idea behind the power grid. As for the "celanness" of hydro 
power, it appears that it may not be as "good" as previously thought. 
By building dams, the natural hydrologic cyclus has been broken. 
Sediments (and thus nutrients to marine life) are no longer flushed 
into the sea as they used to. Which may accout for at least parts of 
the recent decline in fish stocks.

Another peril that has just recently come to attention, is that the 
natural variation in the salinity of the sea water serves as a limiting 
factor to adjust stocks of various creatures. In certain parts of the 
sea, the numbers of "kr&#4294967295;keboller" ("sea porcupines", a kind of mollusc) 
have skyrocketed. As a result, large areas of kelp forests have been all 
but obliterated. The increase of molluscs has tradidionally been explained 
by declination of the numbers of fish preying on them. However, according 
to the marine biologists, the molluscs are very sensitive to salinity: If 
the salinity drops below a certain threshold, they die. And since the huge 
freshwater wash-outs from the rivers that used to happen in spring are 
stopped, the salinity doesn't drop below the mollusc survival threshold 
anymore. 

> all the talk about blackout people here in Phoenix spend hours 
> in line at gas stations to buy gas 3$/gallon because of a broken 
> pipeline. 
> 
> a couple of $ more and it'll reach danish prices ;)

I don't know the danish prices but here one liter of gasoline costs 
between NOK 9 and NOK 10 (some $1.25). A couple of days ago I borrowed 
a Jeep Cherokee and filled the tank. I'll never buy a car with that kind 
of fuel consumption.

Rune