On Sun, 27 Jul 2014 23:49:49 +0100, Tim Watts wrote:

I thought it was more the issue that you cannot phase lock France and
the UK?

No real reason why you couldn't make the channel link work using AC, there are a
number of transmission lines, some with part undergrounded sections in the UK
that are significantly longer overall. No true underwater AC connections
though, the ones that do run underwater (on the grid system at least) all run in
tunnels.

However, the impact of a single point connection and the loss of that connection
was more of a concern, hence the UK - France link is comprised of 2 x 1000MW
links and the AC/DC conversion process permits presettable defined levels of
power transfer regardless of most external conditions so the interconnector is
essentially despatchable 'generation' at the entry point to the respective
countries.

There is also a degree of isolation from system disturbances when
interconnecting at DC which can be very useful from a system stability point of
view.

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