🚀 go-pugleaf

"Howard Berkowitz" <hcb@gettcomm.com> wrote in message 
news:hcb-9D8DF8.09290922122004@news-central.giganews.com...
> In article <cqbq5g$fp6$1@reader1.panix.com>,
> EskWIRED@spamblock.panix.com wrote:
>
>> In ne.general Howard Berkowitz <hcb@gettcomm.com> wrote:
>>
>> > Shorthand for both.  One of the problems of this regulatory split into
>> > generation and distribution is that it did not take engineering safety
>> > into account. The reality is that a number of distribution companies
>> > were spinoffs of existing plant, and were not optimized for
>> > interconnection, being the older AC high-voltage treansmission systems.
>>
>> What do you mean that "a number of distribution companies ... [are] older
>> AC high-voltage transmission systems"?
>>
>> IME, the distribution companies have specs that need to be met before one
>> can interconnect.  What kind of optimization are you referring to?
>
> I'd have to pull out the technical analysis of the last major Northeast
> blackout, but to my recollection, there was a problem of reactive AC
> surges from one of the generating companies, in, IIRC, Ohio.

From what I heard having an electronics tecnician in the family and after 
some discussion with one of my engineering professors I have some up with 
this:
A " null frequency event" was sent through the Eastern grid before the 
cascading blackoutreported by a 3rd parties internet monitoring system in 
Lansuing Mich. where the cascade was stopped  This means that the 60Hz 
frequency wave(which has been the standard scince electricity was first 
used) would have had to have been met by a wave of equal or greater 
magnitude but opposite polarity travelling over the grid (a surge).  At the 
meeting of thse two waves(Currents) the waves will kill each other leaving a 
temporary lack of frequency.  In the threee phase Delta layouts in high 
voltage transmission you could kill all three waves with a single wave of 
opposite current flow such as a ground current. but you would have three 
nodes insted of one.

This is not the cause of the black out though as a wave of this type would 
destroy any generators of opposing polarity because of the forces caused by 
the magnetic field interactions. To prevent this Turbines have nutral 
couplings on their shafts that connect the turbine to the grid.  This 
coupling under the given conditions is distroyed immidiately disconnecting 
the turbine from the grid.  two of the four units at Fermi 2 in Monroe MI 
where lost because of this, proof of the "Erie Loop" reversal given in the 
mass media. As a primary feature however this can be expensive as the whole 
unit has to be taken apart to get to this coupling (I would have hated to 
witness the thing blow)So all Yards of any size have automatic circut 
breakers to prevent a surge from spreading out by disconnecting the opposing 
lines. The blackout was the result of this safety feature not stopping the 
surge most likely by an error in timing. Allowing the surge to dissipate 
over a distance normally

I can verify a pluse however, a brownout In my home city of Windsor ON 
occurred some time  before the full grid "death" indicating two occurrences 
or an undecected pulse. I can exepain this as  Two massive Switch yards 
connect  four 110KV transfer lines through the city from to the Switchyard 
in London ON to the Erie loop. one being from a now rebuilt power plant. The 
London Switchyard controlls power flow flow of the Erie loop back into the 
US through Sarnia by a mssive corridor (>500KV I think) The 8 line corridor 
and yard is viewable for about 20 miles along the 401 before London. I saw 
this by a brownout from a building connected the the power plant's switch 
yard. I also belive the lines that power this city serve as stabilizers for 
the loop.  I belive this as most of the City of 200,000 had power and kept 
power about four hours after the blackout while the radio was continuously 
updating what city was powered and not   Anyway  about half an hour later a 
masive brownout that lasted a good 20 seconds occurred and Toledo was 
reported to have power then Cleveland after another massive brownout a few 
minutes later. Thus establishing the base of the grid the Erie Loop.  My 
guess was they had powered most of the major lines from unaffected Quebec 
and Manitoba and the unaffected parts of the Eastern interconnect directly 
to the Loop with in a very short time. I remember that they where about to 
close the bridge (9:30 I think) then a sudden fury of connections leading to 
US then the loop at 11:00 I think. My parents place was on a feeder 
connected to the bridge and sourced at that power plant yard so we got 
special privildges as they where about to close the largest border crossing 
in North America :) crazy or what? If the Erie Loop reversal cause was 
correct than my experience would prove it.

As for a cause I dont think a bird casing a short circut along the lines in 
Cleveland (I heard was the source apparently 3 of the five lines were on the 
loop direction) could cause such a massive surge.  Even a deliberate attempt 
from that utility would have been absorbed by the others along the loop. You 
would have had to disable all of the switch yards' safety featues along the 
loop to cause this surge and still not have the energy it did!
    You would need a huge amount of energy to cause the kind of surge that 
happened. An amount of energy that would have been generated over a wide 
area and involning some serious magnetic field dsiruption. One that an Act 
of God could only make!!!!!

 >>
>> > Thyristors and other new solid-state components. The Texas grid, for
>> > example, has primarily solid-state DC connections to ther grids.
>>
>> All three interconnects are via DC.  However, within the ERCOT
>> Interconnect, they use the same 60 cycle AC as everybody else.
>
> Perfectly reasonable that AC is used for distribution. Not all
> interconnects in the country are DC.
>>
>> > >
>> > > It is crucial that the interconnecting generator be matched to the
>> > > system
>> > > it is connecing to.  How could it be otherwise?
>>
>> > If you connect with DC, there's no issue of phase and frequency match.
>>
>> > A number of new, extremely high voltage (e.g., 750 KV and above)
>> > transmission facilities are DC, not AC.
>>
>> But no generators interconnect with them!
>
> Agreed. The power is rectified before interconnetion. It would be silly
> economy to replace existing and working AC generators with DC.  It's an
> open engineering issue if future generators, especially in remote
> locations, _might_ be initially DC and convert to AC at regional
> distribution points -- that's an installation-specific tradeoff.

It is more efficient to flatten out a sinusoidal wave than it is to do the 
reverse because of the circutry involved.  In coverting from DC to AC You 
consume more of your load. because of the forcing of the wave shape.  in 
AC-DC coversion you can squeeze more energy.(most AC power devices' 
consumtions are measued by an RMS (DC conversion any way).
    However AC is always going to be generated by a turbine because the 
sinusiodal traces a circular path.  If you wanred to go DC for the grid you 
would have to place an AC-DC coverter at every generation point in the grid 
otherwise you would have to change the way power is generated (not going to 
hapen anywhewre in the near future). Otherwise any point at interfacing 
would require two way coversion. as DC is in a single direction only.  This 
makes the idea of power sharing over a grid difficult requireing a more 
sophisicated system at the appropriate points
Under DC (steady state) any secondary currents seen across a componet would 
be added and power would be taken from the new current but polarized 
componets such as some capacitors capacitors and polarised resistors) can be 
damged or distroyed by any current reversal over time (a capacitor can be 
distroyed by any reversal. Time is affeced by the current strength). If 
anything under a power surge in DC you would not have as severe a result. 
Thus surges as this would not matter.

It is an issue though one that needs to be carefully considered

KT