[Lowfer] Re: Power Outages

[Ed Phillips]

Alberto di Bene wrote:
> 
>  > If the generator starts rotating slightly faster or slower,
>  > it it pulled automatically back in sync. This is caused
>  > by the negative slope of the frequency vs. power
>  > characteristic of the generator.
> 
>  > Yes, the armature (rotor), which carries a DC current, rotates
>  > in synchronization with the grid. As I explained before, this
>  > synchronization is automatic, only the power input to the
>  > turbine is controlled, to set the power output.
> 
> Yes, but there must surely be somewhere a frequency control device.
> The system cannot be self-sustained, just relying on the fact that each
> generator is kept in sync solely by its connection to a power grid with
> energy
> at 50 or 60 Hz. Somewhere something must have set that frequency at
> 50 or 60 Hz.
> Who controls the frequency and how ?
> 
> 73  Alberto  I2PHD

	In the old days (1940) of small interconnected systems some station was
designated the "master" and all others regulated with respect to it.  In
one system with which I used to be familiar the frequency was adjusted
to keep an ordinary synchronous electric clock in step with time ticks
distributed by Western Union telegraph.  That was a small town
arrangement and I'm sure something more sophisticated is used now. 
There are "Power System "Monitors" for sale which use the GPS "1 pps"
signal as reference, with timing accuracy of the order of 100 ns or
better.  I don't know how they are used in today's very large interties
and would be interested to know.  Some station has to be the master.

	What's the practice in your country?

Ed