Voltage Source Converter Stations for Direct Current Power Transmission. Generality

This article presents the fundamental principles and key aspects of the operation of voltage source converters (VSC – ), used in high-voltage direct current (HVDC – ) connections. It is the first in a series of three articles: this first article is devoted to general information on VSC-HVDC stations, the second [D 4 765] will deal with control and protection principles, while the third [D 4 766] will address electrotechnical studies, associated models, and examples of typical behavior in dynamic and transient conditions.

In 1954, the first commercial direct current link, with a capacity of 20 MW/±100 kV, was installed between Sweden and the island of Gotland. Since then, the cumulative power of HVDC transmission installed worldwide has grown steadily, and recently, a dramatic increase in volume has been underway. To date, most HVDC systems installed worldwide are of the line-commutated converter (LCC) type and use thyristor valves (current source converters). Currently, the world's most powerful HVDC transmission line is LCC technology. Commissioned in 2019, it was built by several companies, including Hitachi Energy and NR Electric for the valves, and is operated by SGCC (State Grid Corporation of China). It connects the city of Changji in Xinjiang province to the city of Guquan in Anhui province in China, with a capacity of 12,000 MW/± 1,100 kV over more than 3,200 km. For more information on HVDC LCC technology, an article from Techniques de l'Ingénieur is available at [D 4 762] .

Introduced in the late 1990s, HVDC-VSC technology is based on the use of converters based on IGBTs (Insulated-Gate Bipolar Transistors), allowing for increased flexibility in power flow control, including when reversing the direction of transit, connection...