First 1100 kV HVDC transformer in the world

The World’s First 1,100 kV HVDC Transformer Passed Testing

On January 24, 2018, the world's most potent high-voltage transformer (HVDC) began its journey from SIEMENS's transformer factory in Nuremberg (Germany) to China.


In July 2016, SIEMENS received an order to manufacture four transformers of this type. About a year later, the world's first 1,100KV transformer was completed and successfully passed the test facility tests. The massive size of the transformer poses a logistical challenge for the installation team.


Image of the world's largest transformer


Information about the world's most powerful transformers

  • The world's first 1,100KV transformer for the world's largest HVDC project in China
  • Developed, produced, and tested at the main plant in Nuremberg
  • The world's most powerful HVDC transformer with a capacity of 587 MVA
  • Transformer size: 37.5 x 12 x 14.4 (m)
  • Weight ~ 900 tons

The transformers will be installed at the Guquan converter station of the HVDC connection between Changji (Xinjiang) and Guquan (Anhui) in China. This is the world's most powerful HVDC transmission system regarding transmission capacity, voltage, and length. It will be the first to transmit electricity with 1,100KV DC to anywhere in the world. The HVDC link is 3,324 km long and will transmit electricity from northwestern Xinjiang to Anhui province in eastern China.


With 12GW transmission power, it will replace the most powerful system ever before with 10GW. In these systems, transformers are used to feed energy from a conventional AC transmission grid into the so-called converter station. They generate DC voltage on one side and convert it back to AC voltage on the receiver side.


The HVDC line between Changji and Guquan will be operated by State Grid Corporation (SGCC), a Chinese grid operator. The connection will start working in 2019.


SIEMENS has developed, manufactured, and tested HVDC transformers at its transformer manufacturing plant in Nuremberg. This is the first of 7 transformers of 1,100KV that SIEMENS and a partner company build for the world's most extensive HVDC transmission system. This type of transformer is among the most powerful single-phase units globally, with a transmission capacity of 587MVA. SIEMENS is building transformers in a network of factories led by the Nuremberg plant, cooperating with the HVDC transformer factory in Guangzhou, China, and another Chinese partner. These factories are producing machines according to the specifications and documentation of the main plant in Nuremberg. Put into operation the world's largest HVDC link.


Beatrix Natter, CEO of SIEMENS, said: "With the successful testing of the world's first HVDC transformer for a transmission voltage of 1,100KV, we have set a new standard in transmission DC. Experience and ingenuity are what made this development. It makes direct transmission over long distances more efficient for our customers because higher transmission voltages mean lower transmission losses".


To achieve this feat, engineers developed the valve guide system and the overall design of the transformer. The transformer design itself results from a giant step forward with a 55% increase in the rated power of a one-phase transformer. To produce this giant, SIEMENS has doubled its investment in its factories and test facilities.


Reference articles:

Structure and operation principle of a 3-phase transformer
Step-up transformer

Video about the world's largest transformer

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