Siemens will deliver four transformers, each with a capacity of 400 kV and 315 MVA, on behalf of the British grid operator National Grid. The grid operator will replace the old transformers in the high-voltage direct-current (HVDC) cross-channel link. The new transformers are quieter, have lower transmission losses and will significantly improve the system's reliability. The HVDC link connects France and England and makes it possible to efficiently exchange energy in both directions. The order includes the supply, installation and commissioning of the transformers for the Sellindge converter station in England. Siemens will complete the work by mid-2019.
"These new HVDC transformers will enable our customer to raise its system to a new level of energy efficiency and reliability," says Beatrix Natter, CEO of the Siemens Transformers Business Unit. "We are proud that the customer has placed the order with us as a reliable technology partner." Siemens will install the new units to fit precisely in the system. For example, the wall openings for cooling all devices are located at different points. In addition, all transformers will be equipped with a sprinkler system for fire safety.
All four transformers are being manufactured in the Nuremberg transformer factory. This factory has many years of experience in building transformers and manufactures HVDC transformers of all sizes up to a voltage level of 1,100 kilovolts (kV), which is currently the world record in transformer manufacturing.
National Grid is one of the world's largest investor-owned utilities focused on transmission and distribution activities in electricity and gas in the UK and US. It plays a vital role in connecting millions of people to the energy they use. The company earned approximately €15.1 billion in 2017.
High-voltage direct-current transmission is characterized by significantly lower transmission losses than alternating-current transmission. The HVDC cross-channel link technology thus makes it possible to efficiently exchange energy in both directions via subsea cables across the English Channel. The 73-kilometer link transmits up to 2,000 megawatts (MW), which means that it can supply up to 3 million homes with power on the English side alone. HVDC therefore represents an important portion of the British power supply. The cross-channel link transmits most of its energy from France to the UK and only in rare cases from the island to the mainland.
Siemens has successfully placed several large HVDC links in operation in recent years. In 2018, the company will supply transformers for the world's most powerful HVDC link, which has a transmission capacity of 12 GW. This experience gained over multiple projects secures the company's position as the market leader in HVDC technology.