[time-nuts] Daft idea with the National Grid

[Poul-Henning Kamp]

--------
Hal Murray writes:

> I'd expect an ADEV type pattern.  For long tau, the wander in the system will 
> dominate.  We have lots of long term data so should be able to plot that part 
> of the graph.

I did that some years ago:  The Nordic grid bottomed out around 1e-10, with
a frequency error less than 2e-11 measured over 45 years.

> How much energy is in the rotating turbine and generator?  That should provide 
> a lower limit on the time constant of the control loop.

Answer A: Surprisningly much (do the math on 50 tons of iron, 1m diameter at 3000 or 3600 RPM)

Answer B: Not enough to keep modern grids stable (Google term: "Low inertia conditions")

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