This is being done and it's called synthetic inertia. Just with capacitors and batteries instead of spinning motors.

To my knowledge Siemens is currently making a lot of money by adding spinning inertia to the grid because that is easier than getting the response time/power out of electronics.

Caterpillar provides some really neat small scale flywheel UPS - used in places like hospitals where it would be very bad to lose power. They last long enough for the diesel gennies to start up.

I saw these in the basement of a data center about 11-12 years ago. Most steampunk thing I've seen in real life.

Here's a bigger one at ASDEX (a fusion experiment):

https://www.ipp.mpg.de/4244138/generatoren

I've worked on mine sites that use this as well.

Inverters and batteries (or any other DC source) are also very good at doing this.

Not grid following inverters, or "any DC source", as we saw in Spain in Summer

Nothing to do with the blackout in Spain - https://www.reuters.com/business/energy/what-caused-iberian-... - voltage surge and various thermal power generators failing to provide the voltage correction services they were being paid for

But yes, grid following alone does not provided the required stability - synthetic inertia etc needed

True DC grids avoid this stability issue by not having a phase and allowing power flow to pretty much just self-balance through voltage gradients and clipping of connections/devices to whatever current they can handle.

With enough voltage range that wouldn't even need the tricky loops of voltage regulation common in incandescent-targeted legacy AC grids.

Yes, if you don't install grid stabilization inverters, they don't supply grid stabilization.

From what I saw: In Spain, inverters are not allowed to provide voltage control, and what we saw in Spain, was a voltage spike that caused generators to drop offline, which then caused frequency issues.

See report and first comment: https://news.ycombinator.com/item?id=44358668

It looked to me that regulators wanted to make solar the scapegoat for political reasons.

The report indicates to me that different operators were using a random monkey theory to make changes until the grid stabilised (they clearly didn't have a handle on the root cause of the instabilities). The regulator screwed up: they are supposed to engineer the network so it can be stable (even in the face of political pressure).

Ignore the clickbait headline here: Australia’s Solar Boom Is Breaking the Grid - Or Is It?

It's a sub 15 minute actual grid engineering for lay public explainer video (I know, I'm not a video fan either)

A better duller title might be: How Australia's Grid is being adapted to Solar Boom

  00:00 Introduction
  01:23 The Problem with Too Much Solar
  03:29 Batteries Change the Economics
  05:40 What the Grid Actually Needs
  07:04 A Cautionary Tale – The 2025 Iberian Blackout
  08:21 Australia’s Secret Weapon – Experience with Weak Grids
  10:08 The Genius Technical Fix – Grid-Forming Inverters
  12:25 The Perfect Partner - Batteries
  12:58 From Mechanical to Software-Defined Stability
  13:42 Conclusion – Fixing the Grid Before It Breaks

https://www.youtube.com/watch?v=qavFbOpt4jA