[time-nuts] Logging the grid frequency....

Bill Hawkins bill at iaxs.net
Fri Feb 22 23:21:40 EST 2013


The grid contains a massive amount of inertia in the rotating
synchronous machinery that generates power. The 'springiness'
of the transmission lines allows local noise and even phase
noise that is caused by loads added to or dropped from the
line. Hal Murray (ICBW) had pictures of individual cycles
that were badly distorted by changing taps on distribution

So it is not correct to measure one point to a gnat's nose
hair and call it "the grid frequency."

It might be more accurate to put a flywheel on a synchronous
motor and measure its speed, because the time constant of that
system is a whole lot closer to that of the real grid frequency.

Now, I understand that nobody build things like that any more,
so perhaps a mathematical model of such a system could be solved
by a computer that samples the line voltage at about 100 times
line frequency.

But perhaps I have misunderstood what you have been talking about.

Bill Hawkins

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