A big problem with solid state electronics is fault current handling. The grid would become extremely brittle if it was purely a DC conversion setup. Semiconductors don't do too well outside their happy zone. All it takes is some wind and tree to fire up a very large arc welder. If you can't momentarily handle 10x+ the rated system capacity, you are gonna have a really bad time. Ordinary transformers in oil bath can take a hammering for many cycles. A semiconductor wouldn't make it through one.
replyStill roughly 2x the cost and about 10x lower MTBF.
replyThat seems like it's within striking distance of competitive, no? You get some major advantages in size and production automation. Perhaps it's ok for it to die sooner if you can get it built now and then replace it later.
replywell aside from being effectively 20 times more expensive over entire operation...
replyDC switches (as in, just a power switch) are vastly more expensive because while in AC you have 100 breaks in current a second, DC is constant so it is far harder to break. So even if you had device that could use both (not hard with SMPS, they have rectification as first step), it's still essentially " replace everything".
The protections side is a big problem - most HVDC has circuit breakers operating on the HVAC sides of the link so going to full DC transmission presumably wouldn't eliminate that equipment.
replydeleted
reply