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December 11, 2018 15:17

What technologies would they use for a 1000MW 400kV underwater link?

Just catching up with some reading and found this article which appears an amazing engineering feat.
https://eandt.theiet.org/content/articles/2018/12/uk-belgium-nemo-link-electricity-interconnector-ready-for-use/

Basically 50Hz AC is converted to 400kV and passed under the sea, which is amazing in itself, but at currents up to 2,500A and the direction can be reversed to share the power where it is required! Seem a good technique for sharing excess wind and solar power or just excess generation capacity to save starting and stopping power stations which is a growing issue coping with the randomness of 'green energy generation'.

The article states a "power cable", but that is way out of my knowlege and experience. I also wonder what losses occur in the cable? You can certainly afford to drop a few volts when at 400kV.

So the general question is what technologies lay behind this?

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December 10, 2018 09:14

Hi Boss,

I've come across some resources on the ABB website which talk about the cable type & the technology behind it: 'HVDC Light'.
HVDC- High Voltage Direct Cable

Excerpt:
"HVDC Light is HVDC technology based on voltage source converters (VSCs). Combined with extruded DC cables, overhead lines or back-to-back, power ratings from a few tenths of megawatts up to over 1,000 MW are available. HVDC Light converters are based on insulated gate bipolar transistors (IGBTs) and operate with high frequency PWM (pulse width modulation) in order to achieve high speed and, as a consequence, small filters and independent control of both active and reactive power."

References:
http://www.abb.co.uk/cawp/seitp202/debdfbaa3ccb037fc125797c003de13b.aspx
https://new.abb.com/systems/hvdc/hvdc-light
https://www.energy.gov/sites/prod/files/2013/05/f0/HVDC2013-Tang_0.pdf

This technology is new to me as well and I'm only sharing some content I found useful.
I am hoping another DS member with a greater knowledge of high voltage power transmission can contribute.

Cheers,
Joy

December 13, 2018 13:17

@Joy Ch That is very interesting. I have for many years misunderstood the original England - France HVDC link, that also was an undersea cable on the seabed, I had thought it was a 'cable' within a small bore tunnel :) . Another interesting aspect of these links is they are designed to minimise magnetic disturbance to shipping with the parallel return current link. Wiki also states the original cable was frequently damaged by shipping... this sounds like a spectacular event with 160 MW at 100kV being discharged into the sea or into an anchor chain! These HV links are an interesting and challenging technological achievement.