Venturing into a new dimension of HVDC technology – Siemens is constructing a high-voltage DC link with the world’s highest ever power capacity in China

The additional electric power from Yunnan is intended to supply the rapidly growing industrial region of the Pearl River delta in the province of Guangdong and the megacities of Guangzhou and Shenzhen. In future the electricity generated by several hydro-electric power plants will be transported from Yunnan via 1,400 km to Guangzhou over this long-distance HVDC link. Hydro-electric power generation is economically, environment-friendly and does not emit any CO2. This HVDC link will save the emission of more than 30 million tons of CO2 a year. That is how much of the gas which is harmful to the climate would be produced otherwise, for example through the construction of additional fossil fired conventional power plants in the province of Guangdong to serve the regional grid.

“This outstanding order shows that our efforts over recent years to further develop 800 kV HVDC technology to the point where it is ready for use in projects have been worthwhile. Today, we can boundless provide it to our customers,” said Dr. Udo Niehage, President of Siemens Power Transmission and Distribution Group (PTD).

Together with Chinese partners, Siemens designs the complex HVDC system and supplies HVDC main components, among other things ten 800 kV and ten 600 kV converter transformers as well as DC filters and 800 kV DC components. Furthermore Siemens supports its Chinese partners in design and manufacturing of thyristor valves, converter transformers and control systems. The converter stations operate in bipolar mode with two series-connected, twelve-pulse valve groups per pole, in which light-triggered thyristors are used. This scheme improves the reliability and flexibility of the power transmission.

For Siemens Power Transmission and Distribution this long-distance HVDC link between Yunnan and Guangdong is already the fifth system in China. The first was the “Ge-Sha“ HVDC interconnector linking Gezhouba and Shanghai (1200 megawatts, +/- 500 kilovolts over a distance of 1040 kilometers), which went into operation in 1989. “Tian-Guang“, the second project, which has been in service since June 2001, links Tianshengqiao in southwest China with Guangzhou (1800 MW, +/- 500 kilovolts over 960 km). The third project, the “Guizhou-Guangdong I” interconnector between Anshun in Guizhou Province and Zhaoqing in Guangdong Province (3000 MW, +/- 500 kilovolts over 940 km) entered operation in late September 2004. Number four is the “Guizhou-Guangdong II” project (3000 MW, +/- 500 kilovolts over 1225 km) which will go into service before the end of 2007.

The steep rise in demand for power in China’s industrial centers means that huge amounts of electricity have to be conveyed over distances of one thousand kilometers and more. HVDC transmission is the only expedient method, in terms of both technology and efficiency. High-voltage direct-current transmission is the only technically and economically viable solution. As the current Siemens HVDC project shows, China has now increased the DC transmission voltage of new long-distance HVDC systems to +/- 800 kV due to China’s need for even longer lines and more bulk transmission demand. China is the fastest growing market in the field of power transmission and distribution and will become the world’s largest single market for HVDC transmission technology over the next 20 to 30 years. Siemens PTD is a leading supplier of this technology.