The world’s first transformer, which Siemens developed and manufactured for high-voltage direct-current (HVDC) transmission systems with what is currently the highest transmission voltage of ±1,100kV, recently passed its type test, Siemens said in a release.
Siemens developed, manufactured and tested the HVDC transformer in its transformer factory in Nuremberg. It is the first of a total of seven ±1,100 kV transformers that Siemens and an unnamed partner company are building for what is currently the world’s largest HVDC transmission system. This type of transformer is among the most powerful single-phase units in the world, with a transmission capacity of 587.1 MVA. Siemens is building the transformers in its network of factories led by its Nuremberg plant in Germany, in cooperation with its factory for HVDC transformers in Guangzhou, China, as well as another Chinese partner. These factories are manufacturing the machines according to the specifications and documentation of the lead factory in Nuremberg. Commissioning of the world’s largest HVDC link – and thus also the transformers – is scheduled for 2018.
The workflows for manufacturing and testing this product were challenging due to the transformer’s extreme dimensions of 37.5m (L) x 12.0m (W) x 14.5m (H)
Siemens developed all key components of this type of transformer, thus reaching a new transmission level in HVDC technology. The workflows for manufacturing and testing this product were challenging due to the transformer’s extreme dimensions (LxWxH: 37.5m x 12.0m x 14.5m). Nevertheless, the ±1,100 kV prototype was able to pass every test in terms of functionality, emissions and load level. The type-tested HVDC transformer is now being prepared for its long journey to China by road and sea.
“With successful testing of the world’s first HVDC transformer for a transmission voltage of ±1,100kV, we have set a new benchmark in direct-current transmission,” states Dr Beatrix Natter, CEO of Power Transformers at Siemens Energy Management. “Experience and ingenuity are what made this development possible. It makes direct-current transmission over long distances more efficient for our customers, because higher transmission voltages mean lower transmission losses,” she added.
Deployment: The transformers will be installed in the Guquan converter station of the HVDC link between the Chinese cities of Changji (Xinjiang) and Guquan (Anhui). This is the world’s most powerful HVDC transmission system in terms of transmission capacity, voltage and length. It will transmit power with a DC voltage of ±1,100kV for the first time anywhere in the world. The HVDC link is 3,284 km long and will transmit electricity from the northwestern Xinjiang region to Anhui Province in eastern China. With a transmission capacity of 12 GW, it will replace what was previously the most powerful system with a capacity of 10 GW.
AC to DC: In such HVDC systems, transformers are used to feed power from conventional AC transmission grids into what are known as converter stations. These generate the DC voltage on one side and convert it back to AC voltage on the receiving side. Due to the type of connection to the converters, the transformers will also be loaded with the very high DC quantities of the transmission voltage and current.
Caption: The 1,100kV HVDC transformer’s has extreme dimensions of 37.5m (L) x 12.0m (W) x 14.5m (H). Seven such transformers will be supplied by Siemens for the 1,100kV Xinjiang-Anhui HVDC transmission link in China. (Photos: Siemens)