We (Norway) do have cables connecting us to UK and Europe. They've been a hot topic the last year with the high energy prices. We're making bank on selling our hydro power when gas got scarce. But that skyrocketed our own prices.
It's a difficult topic. It's probably a net win for Norway, as we can produce when price is high, and stop our hydro and import when prices are low. The problem is just that the benefit ends up making the government and the electric producers (again owned by government orgs mostly) rich, but us people have to pay more for our own energy use. So using that extra money earned to help the people is needed.
I would assume those cables aren't frequency synchronized however, they are either a HVDC cable or have DC interconnect somewhere so that the grids aren't frequency synced.
It's a difficult topic. It's probably a net win for Norway, as we can produce when price is high, and stop our hydro and import when prices are low. The problem is just that the benefit ends up making the government and the electric producers (again owned by government orgs mostly) rich, but us people have to pay more for our own energy use. So using that extra money earned to help the people is needed.