On September 9, 2024, the Ministry of Industry and Information Technology published the “Guidance Directory for the Promotion and Application of First Major Technological Equipment (2024 Edition),” in which the “Hybrid Commutation Converter” was successfully included as a new type of power transmission and distribution equipment for the new type power system.

Due to the reverse distribution of power generation resources and electricity consumption in China, the “West-to-East Power Transmission” strategy has become a long-term significant strategy for energy development in the country. High-voltage direct current (HVDC) transmission, with advantages such as large energy transport capacity, long transmission distances, low losses, and flexible control, has become the preferred method for “West-to-East Power Transmission.” However, conventional HVDC systems based on Line Commutated Converters (LCC) face the issue of commutation failures, which seriously threaten the safe and stable operation of multi-drop HVDC grids.

A research team composed of Tsinghua University, Huairou Laboratory, State Grid Henan Electric Power Company, State Grid Corporation of China’s DC Technology Center, State Grid Economic and Technological Research Institute Co., Ltd., Xi'an Xidian Power System Co., Ltd., Xi'an Power Semiconductor Co., Ltd., XJ Electric Co., Ltd., and CRRC Zhuzhou Institute Co., Ltd. adopted the concept of “one generation of devices, one generation of equipment.” From the perspectives of “new solutions, new devices, new equipment,” they proposed a new method for hybrid commutation based on inverse-resistance IGCT devices. They developed a new IGCT device with bidirectional blocking capability, overcoming key technologies for voltage balancing of series-connected devices and high-reliability control protection. They successfully created the world’s first hybrid commutation converter (HCC) with a rated voltage of 120 kV and a rated capacity of 360 MW. After passing all type tests, it is planned for retrofit application at the Lingbao Converter Station unit I of State Grid Henan Electric Power Company.

The project achieved a comprehensive breakthrough from high-voltage, high-capacity converter semiconductor devices and key technologies to equipment, successfully developing the world’s first hybrid commutation converter and tackling the global challenge of commutation failure in conventional HVDC transmission, resulting in a new breakthrough in HVDC technology.

120 kV Hybrid Commutation Converter

The hybrid commutation converter based on inverse-resistance IGCT can be used for the renovation of conventional DC projects or new ultra-high voltage direct current transmission projects, retaining the advantages of large capacity, low cost, low loss, and high reliability similar to LCC conventional DC systems. It can also significantly reduce the reactive power compensation requirements of converter stations. Additionally, it provides new solutions for the safe and efficient delivery of renewable energy from the “Desert, Gobi, Wasteland” new energy base and addresses safety and stability issues for ultra-high voltage DC receiving end grids, showing great potential for widespread application and promotion.