Siemens is manufacturing the transformers in its network of factories, managed by its transformer plant in Nuremberg, Germany, in cooperation with its HVDC transformer plant in Guangzhou, China. The supply volume also includes special converter transformers that can be directly connected to China's 1,050 kV AC grid, something that has never been done before.
"With our transformers and technology, we support a global energy network called the Global Energy Interconnection (GEI)," said Beatrix Natter, general manager of the transformer business unit within Siemens' Energy Management Division. "In this way, we are also helping to interconnect global three-phase ultra-high voltage networks and DC ultra-high voltage networks at the 1100 kV DC and 1050 kV AC levels."
Siemens has completely redesigned all the key components of its 1,100 kV converter transformers, drawing on its many years of experience building HVDC transformers. In manufacturing these transformers, the company is entering a new dimension of HVDC technology. The Changji-Guquan system will transmit power at a transmission voltage of 1,100 kV DC for the first time worldwide. As fundamental components of the HVDC transmission system, converter transformers are responsible for converting the three-phase grid voltage to a transmission voltage of 1,100 kV to supply the converters.
“Our transformers for the advanced HVDC transmission project in China have positioned us as an industry leader,” said Natter. “The innovations being implemented here will benefit our entire product range.” In developing the 1,100 kV converter transformers, the primary objective was to meet the exceptionally stringent requirements imposed on the insulation systems of these high-tech, 1,100 kV voltage-level transformers.
For example, the two valve bushings through which current flows from inside the transformers to the converters are approximately 19 meters long, due to the required isolation distance in the air.
With the bushings, the transformers are 37.8 meters long, 5.85 meters high, and 5.20 meters wide. Filled with insulating oil, they weigh 823 metric tons, and the shipping weight is 490 metric tons.
