Siemens Energy and China Southern Power Grid have put into operation the second pole of a high-voltage direct-current (HVDC) system capable of transporting huge amounts of clean hydro power to Guangdong Province.

The transmission capacity has been doubled to 5000 MW. With one pole operating at plus 800 kV and the other at minus 800 kV, the voltage difference between the poles reaches the world record of 1600 kV dc. In December 2009, the link also set the world record for first dc operation ever at a voltage level of 800 kV dc. Since that date, pole one has operated at nominal power of 2500 MW without any interruptions.

The ecofriendly carbon-dioxide-free power totaling 5000 MW, produced by several hydro power plants in the remote Yunnan Province, 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 carbon-dioxide emissions by more than 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 km (932 miles). 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 km (1864 miles) and even more are feasible now with UHVDC technology of this kind. At a transmission capacity of 5000 MW, losses are as low 2% per 1000 km (621 miles), plus less than 1.5% losses for both converter stations at the sending and receiving end of the transmission line.

Together with its Chinese partners, Siemens designed the 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 dc components.

Visit www.siemens.com.

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