[cesis]

Actually most long-range high-voltage transmission lines are DC.

[japanuspus]

Source?

Long-range high-voltage DC (HVDC) interconnects are being discussed in Europe, and have already been widely deployed in China. For local (100km) connections AC is still used almost exclusively, only exception being for some underground cables where induction losses would be too high.

[cesis]

There are many already existing HVDC transmission lines, e.g.:

https://en.m.wikipedia.org/wiki/File:HVDC_Europe.svg

[giva]

I think they are mostly used when an AC trasmission is impossible: AFAIK only synchronized grids can be connected by AC.

https://upload.wikimedia.org/wikipedia/commons/6/6d/Electric...

[emilfihlman]

You are entirely correct. Power between different AC regions is mostly transferred using HVDC-links because it avoids synchronisation requirements between them.

Additionally the capacitive losses of an undersea HVAC cable are prohibitive, leaving only HVDC as an option.

[emilfihlman]

You'll notice almost all of these are undersea cables. HVDC connections are used there because you can't really hang air cables over the ocean and the capacitive losses of HVAC cables under the sea makes them prohibitive.

[dreamcompiler]

Not most. Some.

[emilfihlman]

This is just simply not true.