I must have somehow missed the part about how the new solid state transformers work.
MY LATER ADDED COMMENTS: I define "solid state" as using semiconductors rather than VACUUM TUBES!
IFF you choose to define "solid state" differently than that, please do provide that definition so that we will be speaking the same language!!
I have specified a whole lot of transformers in my career, and most of them are constructed as SOLID assemblies, with o moving parts. Many of them are encapsulated into a solid block to inprove heat transfer and vibration damage. THOSE units are quite soid indeed.
The one characteristic of all transformers is that they use magnetic fields to transfer energy and power. The only "motion" is the electric current flowing in the windings.

 

Found a whole bunch of information on them. Sounds like taking what is already the front end of any standard switching supply packaging it up to accept much higher voltages in the order of 800V seems made mostly for AI data centers, EV fast chargers. they are bidirectional meaning they can feed excess power back to the grid. they are also used in commercial Solar power grids. So I think they already are taking over in a round about way.

 

A bi-directional (or 4-quadrant) converter by another name.
Interesting for data centers which must squeeze the very last available watt from the grid.

 

So it would see a rather limited and specific use for the Solid-State-Transformer.

 

 

Each have their uses and place in systems.
They're useful on wind turbines to produce a constant output from a wind blade turning at a variable speed as the wind changes. The rotor pitch is changed to get maximum power from the wind resulting in varying speeds generator rpm. These units can change the varying frequency & voltage input to a co constant voltage and frequency output.

But you wouldn't use one to transform 400kV to a lower voltage for use in the grid.
Or even transform up to 400kV?

 

At this point I believe that those folks are speaking a different language that us, and that the words in their language have different meanings.

IN that different language it seems that a "Transformer " is a SYSTEM that accepts one voltage (AC or DC) and delivers a different voltage output (AC or DC). NO DESCRIPTION is provided for the mechanism producing this effect except the word "transformer".
In MY LANGUAGE a transformer is a device that changes AC power at one voltage into AC power at a different voltage. I see that the subtle difference is lost to the folks describing the system.