[Milsurplus] Even Worse
Albert LaFrance
albert.lafrance at coldwar-c4i.net
Mon Jul 5 14:50:54 EDT 2010
Sounds like you'd need a real computer (forget that Windows stuff) to figure
it out:
http://long-lines.net/other/electrical/ElectricalWorld-1955-12-12/009.html
This is actually one of the smaller models!
Albert
-----Original Message-----
From: Peter Gottlieb [mailto:nerd at verizon.net]
Sent: Monday, July 05, 2010 2:37 PM
To: jfor at quik.com
Cc: Albert LaFrance; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Even Worse
This is not necessarily true. Long transmission lines are very
inductive, and dense cities (Boston, Detroit, NYC) with metal shielded
underground transmission lines can be quite capacitive. One real-life
situation that we modeled was the loss of a local feeder which caused
power flow through much longer transmission lines. This caused a step
change in reactive to higher inductance and was enough to de-stabilize
the system. These changes play out over seconds or tens of seconds,
surprisingly enough.
As models get larger, due to limited computational power,
simplifications have to be made. There is a lot of work being done now
to make sure the simplifications made are correct!
Peter
J. Forster wrote:
> The real issues in network stability are that, because of the large
> rotating inertias of generators, a rapid phase change is all but
> impossible. To change the phase of a machine with respect to the network,
> you have to speed it up a tad (more steam), let the phase change, and then
> slow it back down (less steam). This cannot be done quickly.
>
> Furthermore, in a simplified case, if you have just two AC generators
> connected together, the can "rock" against each other in phase (rocking is
> a variation of the relative phase of the rotors), and the rocking is very,
> very lightly damped. Extend this issue to a network with hundreds of
> machines and you have a giant mess.
>
> -John
>
> =================
>
>
>
>> The real use of synchrophasors is not for power setting (that can easily
>> be done by far less complex methods) but for early indication of grid
>> disturbances. This is getting more valuable as the control of the grid
>> is moving to a model-based design. Humans just can't interpret and
>> respond fast enough to prevent cascading problems.
>>
>> Peter
>>
>>
>> J. Forster wrote:
>>
>>> Ah, yes. Phase shifting is easy in a polyphase system. For example, a
>>> Scott connected transformer can change 2 phase to 3 phase, or the
>>> inverse.
>>>
>>> Thanks,
>>>
>>> -John
>>>
>>> ==============
>>>
>>>
>>>
>>>
>>>> Yes, it's done with a specialized tap-changing transformer called a
>>>> Phase
>>>> Angle Regulator. This paper describes how they're used:
>>>>
http://www.npcc.org/viewDoc.aspx?name=Phase+Angle+Regulator+Operation+-May+2
>>>> 000.pdf&cat=LEER
>>>>
>>>> Albert
>>>>
>>>> -----Original Message-----
>>>> From: milsurplus-bounces at mailman.qth.net
>>>> [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Larry Godek
>>>> Sent: Sunday, July 04, 2010 6:10 PM
>>>> To: nerd at verizon.net; Milsurplus at mailman.qth.net
>>>> Subject: Re: [Milsurplus] Even Worse
>>>>
>>>> Do power companies share power back and forth according to peak periods
>>>> by
>>>> changing the phase slightly? Where did i come up with this idea? I
>>>> really
>>>> don't remember.
>>>>
>>>> Larry
>>>> W0OGH
>>>>
>>>>
>>>> --- On Sat, 7/3/10, Peter Gottlieb <nerd at verizon.net> wrote:
>>>>
>>>> From: Peter Gottlieb <nerd at verizon.net>
>>>> Subject: Re: [Milsurplus] Even Worse
>>>> To: jcoward5452 at aol.com
>>>> Cc: jfor at quik.com, milsurplus at mailman.qth.net
>>>> Date: Saturday, July 3, 2010, 1:46 PM
>>>>
>>>> The power companies already do that and is able to compare phasors
>>>> across the grid. Check out NASPI, the North American SynchroPhasor
>>>> Initiative.
>>>>
>>>> I set up a PMU (Phasor Measurement Unit) at my plant already, it uses
>>>> GPS for time sync.
>>>>
>>>> Peter
>>>>
>>>>
>>>>
>>>> jcoward5452 at aol.com wrote:
>>>>
>>>>
>>>>> Here at our secret development Lab, we phase lock the 60~ to a GPS
>>>>>
>>>>>
>>>> receiver. This is how you make all the frequencies in the audio
>>>> spectrum
>>>> exact. This is really no secret as most Laboratories have a "house"
>>>> standard
>>>> derived from a GPS receiver.
>>>>
>>>>
>>>>> Jay
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: J. Forster <jfor at quik.com>
>>>>> To: Richard Brunner <brunneraa1p at comcast.net>
>>>>> Cc: milsurplus <milsurplus at mailman.qth.net>
>>>>> Sent: Sat, Jul 3, 2010 1:06 pm
>>>>> Subject: Re: [Milsurplus] Even Worse
>>>>>
>>>>>
>>>>> There is a thread on another list about radioactive tubes. I replied:
>>>>> "And, isotopically pure Thorium likely costs $millions / pound.
>>>>> What an opportunity for the Audiophools! Now, your Tube Amp can be
>>>>> onstructed with eviro-pure tubes. No harmful radiation to contaminate
>>>>> the
>>>>> larity of the sound. We at, PT Barnam AudioLabs, use only isotopically
>>>>> ure Thorium cathodes!!"
>>>>> :-)))
>>>>> -John
>>>>> =============
>>>>>
>>>>>
>>>>> This is beyond witless. Who are these people with so much money and
>>>>> so
>>>>> little sense? I notice they also can't spel, so it's consistent.
>>>>> Imagine, three brass spikes!
>>>>>
>>>>> Richard, AA1P
>>>>>
>>>>>
>>>>> On Sat, 2010-07-03 at 08:57 -0700, J. Forster wrote:
>>>>>
>>>>>
>>>>>
>>>>>> http://www.cruzefirstaudio.com/tripoint.htm
>>>>>>
>>>>>>
>>>>>>
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>>>>>
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>>
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