Edit: I again made the mistake to comment on a thread dealing with energy x politics. Sorry, I'll try not to do that again. I'm out. It's feral.
The trick is the "HV" part. China is already running 1100kv on some of their HVDC lines. Transmission losses decrease with the square of voltage, so any increment from that point would be very substantial.
I didn't see any feral responses? Did you not like the ones that pointed out that losses over 800km are <3%, and so your assertion that Ohmic losses are the issue is essentially wrong?
What voltage is UHVDC at those numbers? Who is supplying the equipment? Where are the demo installations? What's the cost?
Again, the goal is economic very long distance transfer of electric power. Not a Chinese university research project.
> "HVDC transmission has typically 30-50% less transmission loss than comparable alternating current overhead lines. (For comparison: given 2500 MW transmitted power on 800 km of overhead line, the loss with a conventional 400-kv AC line is 9.4%; with HVDC transmission at 500 kV, it is only 6%, and at 800 kV it is just 2.6%.)" [1]
There are quite a few of UHVDC lines in China, not much in the rest of the world. [0] I don't know what they cost, but maybe you can estimate it based on what they decided to invest over a 10y period.
[0] https://en.wikipedia.org/wiki/Ultra-high-voltage_electricity...
[1] https://web.archive.org/web/20180730045905/https://www.sieme...
As a first guess, one would think it makes more sense to eat 30% loss (so you need 1/0.7=143% installed capacity) than to need 200% capacity plus batteries since it's night about half the time on average. And afaik HVDC is more on the order of ~15% loss