I first heard about use of series capacitors in an electric power systems class, 1H 1975, so they have been around for quite a while. It would seem to me that the caps should be able to withstand the DC potential set up by a Carrington event.
Any component for a high voltage transmission line is going to be gigantic. Google term "power transmission line series capacitors" should get you started.
An alternative way of minimizing the effects of a severe solar storm on the grid would be placing series capacitors on the long AC transmission lines. This is done already to increase power transfer capacity of some lines.
Since the solar flare is visible many hours before CME hits, the utilities should have time to configure the grid for the storm. The oerative word here is "should".
The transmissions on current GE and EMD diesel electric locomotives are about 94% efficient from the output of the prime mover to the driving wheels. I would expect electric car motors to be on the order of 90 to 95% efficient, so this should compare favorably with a mechanical tranny.
Speaking of locomotives, the free piston gasifier was being heavily researched in the 1950's as a more efficient realization of a gas turbine and something that could compete with diesel engines as prime movers.