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

[Andy Talbot]

It ought  to be possible to build inertia, electronically, into inverters.
 The maths can't be difficult to fathom-out, then DSP can do the rest.
 BUT to allow this to be possible, in normal usage the solar/wind/whatever
source must be operating at a level significantly below what it can give
out, in order to be able to push out more energy in a hurry when, say,
frequency drops too much.
The operators of such systems will have to be mandated or incentivised to
run backed off at all times in case their extra capability is needed for
emergencies.

Andy
www.g4jnt.com



On Wed, 9 Mar 2022 at 08:58, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> --------
> 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
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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