Richard Clark wrote:


The conjugate argument is unnecessary and in error as a response to
my
posting.


Good. Glad we've come to an agreement on that one.

In the isochronous mode, varying field current changes the terminal
voltage of the generator. In parallel mode, varying field current
can't significantly change grid voltage. But it does change the
reactive power output (MVAR or kVAR) of the generator, as you said.

This is matching explicitly. Not quantifying the load does not make
it something other than R =B1iX Ohms

When quantified, it would undoubtedly lead to very small Rs and Xs,
but all the while, the angles they resolve to are always significant.

In every sense of the term Matching, there is not a jot of difference
between these applications (AC/RF) except frequency and magnitudes of
voltage and current (and not always that).

This isn't impedance matching, it's simply supplying the demand.

Absolutely no difference between applications.


Yes there is. The operator of the generator has the freedom to adjust
power output from 0 to 100% of rated and VAR output between the maximum
incoming and outgoing rated values. No matching required. I sense
that you are beginning to argue my side of the case for me. Please
give me appropriate credit.


not to cause any
kind of mathematical match between the generator's internal X and
the
system's X.

Not demonstrated, in fact your entire recitation argues to the
contrary. My Power Transmission handbooks say quite explicitly that
manual or automatic operation attends to the phase shift by
necessity.
Even if you don't calculate any quantified value it remains as a
mismatch until intervention.

Trying to draw this back into the Conjugate is, again, a misread of
the distinctions between Conjugate and Z Matching. The two are
frequently mixed in discussion (through error), but they are not the
same.


Agreed; please stop bringing conjugate matching into this. You've
already accepted the fact that it doesn't apply.

So we're not matching to any specific
impedance, but supplying load and maintaining voltage.

This statement is simply unquantified Matching.

A story transmission guys like to tell is how they may use open
ended
transmission lines as a kind of capacitor bank. Say there's a line
100
miles long from my plant to somewhere that's not needed to carry
load.
The system controller might connect it at my plant's end but leave
the
breakers open at the far end. A line has both capacitive and
inductive
reactance of course, but when unloaded, the capacitive dominates.

This is classic matching technique at ANY frequency and has been part
of the canon for more than 100 years.


No it is not. You are making oblique reference to the use of stubs in
RF matching. In that application, the length of the stub in degrees is
critical. In the one I describe, the length of the line is random; it
is being used for its capacitance only. It could be replaced by an
equivalent capacitor to produce the same effect. The same is not true
of a matching stub.


So
the trick of the trade is to use it to supply reactive MVARs. The
point of the story in this context is that the controller isn't
concerned about SWR on this extremely mismatched line.

Actually, the concern is quite fundamental and has also been part of
the canon for more than 100 years.

Who would want a generator that was
constrained to operate at some fixed ratio of real to reactive
power?

Hi Nick,

Who would want a generator that was constrained to supply only
toasters? Such strawmen arguements can be lined up from here to the
moon.


Kind of like canons and "known for more than 100 years"? Empty
supercilious statements that say nothing?


One of my Power distribution handbooks (ca. 1907) is not shy to the
matter of Generators seeing the products of mismatches:
"Thus a wave passing from one part of a circuit to another
having a greater ratio of inductance to capacity will develop
an increased voltage and decreased current. This
explains the breaking down of windings, due to
surges entering them."

I don't have to say SWR for it to be evident in the nature of the
description above. I don't have to say Z matching for it to be
evident in the nature of the corrective action. I don't have to say
X
for it to be evident in the myriad of phase drawings and calculations
that are offered page after page.

The old practices could measure Gamma or Rho as we describe it in
this
forum. Calling it VAR does not make it a mysterious process confined
to 50/60 Hz, it is simply a term that describes the same thing and
follows the same dynamics and is reduced by the same operations. We
shift the phase using a variable capacitor or a variable inductor.
In
the plant the same thing is done through adjusting field excitation
(or any number of tricks that are available to the RF craft too).
The
trig is identical as are the results.

Finally, the use of the term VARs is not a power engineer's sly attempt
at obfuscation. It is a common and well defined term in daily use.
73--Nick, WA5BDU


=20
73's
Richard Clark, KB7QHC