Transmitting electricity is quite a bit different from transmitting bytes. That's the main reason we are using Alternating Current rather than Direct Current to power virtually everything.
Was referring to NorNed, a 500km HVDC 700MW interconnect between the Netherlands and Norway https://en.wikipedia.org/wiki/NorNed,
and the Russian power grid IPS/UPS https://en.wikipedia.org/wiki/IPS/UPS
edit - the limits to how far you can push transmission are very high indeed. For instance, here's a study from 1984 that puts an upper limit on AC at 3000 - 4000km and for DC at 7000km. http://large.stanford.edu/courses/2014/ph240/sell1/docs/pari...