The transformer has been designed and developed by Siemens for the HVDC transmission link, which will be operated by the transmission grid operator State Grid Corporation of China (SGCC).

In 2011, Siemens secured a contract to deliver a total of seven ±1,100kV transformers for the world’s largest HVDC transmission system. The transformers are being developed in partnership with undisclosed company.

With a transmission capacity of 587MVA, the prototype transformer has been tested by Siemens at it transformer factory in Nuremberg, Germany, for its functionality, emissions and load level.

Siemens energy management power transformers CEO Beatrix Natter said: “With successful testing of the world’s first HVDC transformer for a transmission voltage of ± 1,100 kilovolts, we have set a new benchmark in direct-current transmission.

“It makes direct-current transmission over long distances more efficient for our customers, because higher transmission voltages mean lower transmission losses.”

The planned 3,284km-long 1,100kV HVDC transmission link between Changji, Xinjiang and Guquan Anhui has 12GW of transmission capacity. The project is scheduled to be commissioned at the end of 2018.

The transformers are planned to be installed in the Guquan converter station of the HVDC link.

Siemens said it has reached new transmission level in HVDC technology by developing all key components of this type of transformer.

Natter earlier said: "With our transformers and our technology, we support a global power grid, called Global Energy Interconnection, GEI.

"In this way, we are also helping to interconnect the global ultra high-voltage three-phase grids and ultra high-voltage DC grids on the 1100 kV DC and 1050 kV AC level."


Image: Siemens-built HVDC converter transformer for ±1,100 kV level. Photo: courtesy of Siemens AG.