HVDC Classic

Time-tested and future-proof

Energy systems around the world are becoming increasingly decarbonized, distributed – and demanding. That’s why HVDC Classic steps into the limelight: It provides transmission system operators with an exceptionally economical and efficient opportunity to supply load centers with the required amounts of power, stabilize heavily strained AC grids, and interconnect grids across regions and countries. The proven technology behind HVDC Classic, which is based on line-commutated current-sourced converters (LCC), has been continuously improved over the years. Today, HVDC Classic systems from Siemens transmit up to 10 GW of power, this way providing the secure, stable, and profitable backbone for today’s increasingly complex transmission systems.

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Why HVDC Classic?

Pave your high-performance power highways

Today, many transmission system operators are required to provide additional grid capacity, improve grid performance and resilience, and contribute to CO2 emissions reduction through the integration of power from renewable sources. HVDC Classic provides the opportunity to tackle these challenges successfully. 

The key to reliable, efficient long-distance power transmission

  • Transmission capacity of more than 10 GW per bipolar system at a voltage level of ±800 kV (± 1100 kV)
  • Highly efficient converter stations with losses of approximately  0.7% of rated power
  • Significantly lower costs for rights of way and overhead lines than with comparable AC solutions
  • Possibility to transmit power over more than 2,000 km for infrastructure improvements
  • Compensation of dynamic AC system disturbances possible through high overload ratings 
  • Capability to interconnect large grids and stabilize parallel AC systems

Take the direct route for bulk power transmission

Growing power demand and the worldwide push for the decarbonization of energy systems call for new approaches in power transmission. The challenge is to transmit power from lucrative but far off renewable energy sources right to the load centers. UHV DC technology from Siemens provides the efficient, reliable solution.

How to transmit more power over longer distances at lower losses

At the core of a UHV DC system is the converter. It consists of a number of thyristor modules equipped with Siemens thyristors of up to 6-inch. Typically, the valves of one pole are arranged in two series-connected 12-pulse groups to overcome possible transport limitations. A major benefit of this layout is the relatively small size of the converter transformers. It also increases the redundancy of the system, as each of the four converters can be bypassed with the assigned DC line still operating at a reduced voltage level of 400 kV. 


The next level of HVDC technology was ushered in when Siemens developed its 6-inch thyristor and all other components required for UHV DC converter stations. Thanks to the ability to produce the entire range of components required for 800 kV DC power transmission, Siemens can supply turnkey solutions for complete UHV DC systems. 


Yunnan-Guangdong, the world's first UHV DC project, which had been contracted to Siemens by China Southern Power Grid in 2007, started commercial operation of the first pole in December, 2009. The first system equipped with 6-inch thyristors from Siemens, the Xiangjiaba-Shanghai UHV DC system in China, commenced operation in 2010. Another huge Siemens ±800 kV UHV DC project is being implemented in Brazil at the moment.

Learn more about HVDC Classic

Download our HVDC Classic brochure to gain an overview of all technical details and possible applications.

Power Transmission Service

Siemens supports the development of the power tramission and distribution grid with its strong team of experts and a number of services.


HVDC Classic: a preferred solution all over the world

Transmission system operators all over the world choose HVDC Classic and rely on Siemens’ unique solution expertise and proven experience in tackling even the most complex challenges.