My God!,
Why would you not want a power upgrade like this?
Especially to negate the burning of fossil-fuels. crazy
New Zealand has a system like this, run mainly overhead from Benmore hydro dam in Otago under Cook Strait with 500kVDC, the total length is 610km.

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3 power stations using mainly mazut

Mazut?

The station at Benmore here is miles away from anything, it had a LARGE rectifier bank in it, I visited it during my apprenticeship training as a Liney, it had a large buzzing sound before you even get near the place.
That was back in the days of LARGE Mercury Arc rectifiers, they are all solid-state these days.

I have also seen the other end of it at Haywards, west of Wellington, where the 3 (5) cables exit Cook Strait and head into an Inverter bank, nitrogen transmission system and switching station, there is no noise at all from the inverter banks, apart from the steady fans that keep the heatsinks cool.