[time-nuts] Re: One-night experiment: empirically verifying that the west coast power grid is actually interconnected

[Poul-Henning Kamp]

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Jeremy Elson writes:

> Wow! I was not expecting the two curves to match up so well. What a beautiful result!

The effective impedances of the power grid are very low, so frequency
discrepancies are almost physically impossible.

If you want to see the real trouble, you need to GPS referenced high
resolution phase measurements in two or more locations, and then
plot the RMS of their differences.

Traditionally the grid frequency has been stabilized by the inertia
in the (huge!) rotors in centralized power plant's turbo generators.

Solar power generation is instantaneous and contribute no inertia.

Wind power has lots of small generators, but they are behind electronic
"frequency converters", (AC->DC->AC conversion) which attenuates and
delays the response from their generators inertia[1].

With solar and wind taking over, for instance 60% of planned new
generating capacity in USA next year will be solar and batteries,
"low inertia situations" have become a real worry.

The UK's grid collapse a couple of years ago is the first documented
case where "low inertia" was "but for" factor.

The big-iron-wound-with-copper manufacturers have started hawking
"inertia generators" as a solution:  Huge spinning lumps of iron
connected to a motor-generator.

Other solutions are to mandate local battery-storage and inertia
supplying control algorithems at large VE deployments.

NREL has a good article called:

	Inertia and the Power grid: A Guide without the Spin

	https://www.nrel.gov/docs/fy20osti/73856.pdf

Poul-Henning

[1] Different control-algorithms in different wind generators on
the same grid-radial could cause frequency oscillations, if the
interactions are not taken into account.  This mandates quite
conservative control strategies, which further attenuates the
"inertia contributions".

[2] https://www.eia.gov/todayinenergy/detail.php?id=51518

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