Issue 14/12 HVDC/FACTS - Highlights

5000A DC Siemens commutation breaker successfully

tested in China

Cutting-edge DC commutation breaker ensures reliable operation to supply sustainable power to China’s megacities in the delta area of Yangzi River.

Siemens DC commutation breaker for the highest rated DC current of 5000A passed successfully the

switching test at the Shuanglong converter station Sichuan in China. Siemens supplied DC commutation

breakers for the ultra-high-voltage direct-current (UHV DC) transmission project Xiluodu-Zhejiang from the

purchaser State Grid Corporation of China.

In January 2013 Siemens got the order to supply special DC equipment at 5000 ampere (A) rated current

level such as wall bushings, bypass breakers and DC commutation breakers with their local partner XD Xian

for this 8 gigawatt (GW) UHV DC project with one of the most powerful transmission lines in the world.

Starting operation in July 2014 the 1670 kilometer (km) power link transports clean hydropower at a voltage

level of ± 800 kilovolts (kV) from Xiluodu hydropower station in Sichuan province to the highly industrialized

Zhejiang province.

The test took place during the high-water level

season to provide the necessary power from the

hydro power plant.

“Siemens DC Commutation Circuit Breaker has

been successfully tested in operation at full load

at 5000A DC in Sichuan China. Siemens has

proven the switching capability without current

flow reduction for the currently biggest UHV DC

transmission,” says Cristen Schimpf, Vice

President for High-Voltage DC Transmission

Solutions.

Fig. 1: Site view of the converter station Sichuan, China

http://www.siemens.com/FACTS http://www.siemens.com/HVDC

Issue 14/12 HVDC/FACTS - Highlights

The DC commutation breaker is integrated in the DC yard as a Metallic Return Transfer Breaker (MRTB) and

allows the re-configuration of the DC circuit. It typically requires capabilities to commutate the DC currents from

one path to another, e.g. from metallic return to earth return. With this innovative technology Siemens enables

reliable transmission of clean CO2 free power at highest loads.

Siemens already has a proven track record in China as a pioneer for the further development of for UHV DC

systems since its world first contract from the CSG (China Southern Power Gird), for a DC transmission systems

at + 800kV in 2007. In 2010 the purchaser State Grid Corporation of China commissioned the longest 6.4 GW

UHV DC Xiangjiaba-Shanghai, transmission system with at that time the most powerful thyristor valves and

power transformers from Siemens. In 2012 Siemens technology contributed to the world’s first UHV DC with 7.2

GW, in the Jinping-Sunan project, followed in January 2014 by Hami-Zhengzhou as the first 8 GW UHVDC

project and from the same customer.

Fig. 2: Xiluodu hydropower station in the Sichuan province

Another important aspect is the circumstance that only superlative 800-kV HVDC technology used in the

mentioned projects allows transporting such huge amount of eco-friendly CO2-free hydropower to megacities, in

total 29.6 GW which is the equivalent of approximately 30 large thermal power plants. That makes Siemens one

of the world's leading providers of innovative technology and sustainable solutions.