China Southern Power Grid, with the help of Siemens Energy, has put into operation the second pole of the world-record HVDC system, which is capable of transporting huge amounts of clean hydro power to Guangdong Province. The transmission capacity has now been doubled to 5000 MW. With one pole operating at plus 800 kV and the other at -800 kV, the voltage difference between the poles reaches the world record of 1600 kV DC. In December 2009, the link had also set the world record for first DC operation ever at a voltage level of 800 kV DC. Since that date, Pole 1 has operated at nominal power of 2500 MW without any interruptions.

“This has been an ambitious project including ground-breaking product developments and we have ultimately even managed to complete it ahead of schedule. With DC systems operating at ultra high-voltage levels we now have the transmission technology of the future in our portfolio. This technology is ideal for transporting clean, renewable power over thousands of kilometers to consumers – with nearly zero losses,” said Udo Niehage, CEO of the Power Transmission Division of Siemens Energy.

The ecofriendly, CO2-free power totaling 5000 MW, produced by several hydro power plants in the remote Yunnan Province with its high levels of rainfall will be transported with minimal losses to the rapidly growing industrial region in the Pearl River delta in Guangdong Province with its megacities Guangzhou and Shenzhen. This will reduce annual CO2 emissions by over 30 megatons compared with equivalent fossil-fueled power plants in the power grid of Guangdong Province.

The Yunnan-Guangdong UHVDC system covers a transmission distance close to 1500 kilometers. The new ultra-high voltage level of 800 kV offers global transmission operators economical low-loss bulk power transmission over even longer distances. Distances of 3000 kilometers and even more are feasible now with UHVDC technology of this kind: At a transmission capacity of 5000 MW losses are as low as around two percent per 1000 kilometers, plus less than 1.5 percent losses for both converter stations at the sending and receiving end of the transmission line.

Together with its Chinese partners, Siemens designed the entire HVDC system for the Yunnan-Guangdong project and developed and supplied the core components for this technology, which included 800-kV and 600-kV converter transformers, DC filters and all 800-kV direct-current components.