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HVDC - Ultra High Voltage

Staying ahead of the curve: 800 kV

Ultra High Voltage Direct Current (UHVDC) transmission, with voltages of up to 800 kV, is the choice being made by many energy managers around the world for the future network developments.

With generation sites becoming farther and farther away from load centers, HVDC is particularly economical for transmission distances greater than 700 km.

HVDC can transmit three times as much power per tower compared with conventional AC. This means a substantial reduction in land costs and often no new right-of-way (ROW) access permits, particularly difficult in densely populated regions.

UHVDC transmission maintains all the technical advantages associated with HVDC transmission: back-to-back or point-to-point connections for synchronized or asynchronous networks, regardless of voltage or frequency. Fully controllable, all HVDC systems prevent faults from propagating and reduce overall associated transmission losses. 

However, UHVDC provides even greater advantages when applied to the very high power levels and long distances required by many large rapidly industrializing countries/regions, where rates of load growth are very high and sources of generation may be thousands of kilometers away from the load centers.


  • Reduced right-of-way requirements for an overhead line.
  • Less land is required and visual impact is reduced.
  • Reduced infrastructure

Turnkey Project Steps

Alstom Grid has the skills, experience, the network and local resources to reliably complete and deliver a turnkey UHVDC system.

  • Engineering and design: Detailed studies and design of all necessary equipment, systems and civil works.
  • The timely completion of civil works, which requires efficient site management, is vital to the timely completion of the project.
  • Equipment and systems manufacturing is realized by Alstom Grid factories or its sub-suppliers.
  • Installation occurs as soon as equipment arrives on site.
  • Commissioning: After equipment verification, control software is installed and the entire system is tested, before handing over the site to the client for commercial operation.

Key benefits 

  • Reduces environmental impact
  • Reduces transmission losses
  • Increases system efficiency
  • Reduces land usage and infrastructure costs
  • The most efficient transmission over long distances