ABB's cable system test environment in Zurich

Breakthrough in HVDC power cable technology

Technology that doubles the power flow of high-voltage direct current cables could make it cheaper to integrate offshore wind farms into the grid.

Swiss engineering group ABB has developed a system that allows HVDC cable to transmit up to 2.6GW of power – enough energy to power two million homes, or serve the electricity needs of Paris.

The new 525kV cable system offers a 64 percent increase over previous 320kV systems – currently the highest voltage deployed for this type of technology – and it will also expand the cable's reach to distances of 1,500km up from less than 1,000km, all while keeping transmission losses under 5 per cent.

The technology uses a new cross-linked polyethylene insulation material and can be deployed underground or beneath the sea making easier it to transmit electricity through densely-populated or environmentally-protected area, potentially reducing the need for unsightly overhead power lines, according to Claes Rytoft, ABB's chief technology officer.

The firm, which makes products used by oil, mining and utility companies, hopes the new system will encourage electricity supply companies to invest in more large renewable energy projects due to lower installation costs.

"Germany is installing a lot of offshore wind farms at the moment with a typical capacity of 1 GW. This means for every GW they have to install a separate cable system to the shore," Rytoft said in an interview.

"With this technology they have the option to connect two offshore wind farms and only have one cable to the mainland."

Rytoft sees a further application in long-distance power corridors, such as Germany's "SUED.LINK" project, announced in February, to carry surplus wind energy from northern regions to the industrial heartland of Baden-Wuerttemberg in the south.

Two years ago ABB developed a circuit breaker that makes it easier to send electricity through HVDC lines into the grids that link power stations to consumers, and while Rytoft conceded this latest development was more "incremental" than the previous breakthrough, he believes it will help pave the way towards what ABB hopes will be a multi-billion dollar market for DC grids.

Conventional grids use alternating current (AC), but it is less efficient at transferring power over long distances and less compatible with some forms of renewable power generation. HVDC can transmit 30 to 40 per cent more energy than conventional overhead lines carrying AC, making it a better for bringing power from distant sources.

"The two inventions put together make it more feasible to build a DC grid," Rytoft said.

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