I must have somehow missed the part about how the new solid state transformers work.

 

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?