Yunnan-Guizhou Interconnection Project - the World's First ±500 KV Three-terminal DC Transmission Project - a Lynchpin in “Operation Beforehand”

A Yearly Addition of Six TWh of Hydro Power from Yunnan will be Transmitted to the Greater Bay Area

The Luquan Converter Station of Yunnan-Guizhou Interconnection Project is the 500 kV converter station at the highest altitude in the world.

On June 11, the Yunnan-Guizhou Interconnection Project, the world's first ±500 kV three-terminal DC transmission project, was completed and the three-terminal bi-polar transmission system was put into operation 19 days ahead of schedule.

The project marked the establishment of a power interconnection and distribution complex between Yunnan and Guizhou. This system is expected to transfer an additional 6 TWh of clean hydro power from Yunnan to the Guangdong-Hong Kong-Macao Greater Bay Area each year, reducing more than 1.8 million tons of standard coal consumption and 4.8 million tons of carbon dioxide emissions. It will contribute to a bluer sky for the country and support the consumption of clean hydro power generated in Yunnan and the construction of the Greater Bay Area.

The Yunnan-Guizhou Interconnection Project is a key national power transmission and transformation project, an icon project of China Southern Power Grid in implementing the central government-directed Western Development Strategy and green development.

The project will ramp up CSG's energy transformation and high-quality development.

With an investment of 3.826 billion RMB, CSG engineers have built a new converter station in Luquan, Yunnan and a one-channel DC transmission line stretching 391 kilometers to connect Luquan Converter Station and Gaopo Converter Station, the latter being the HVDC sending end of Gaopo-Zhaoqing transmission line.

CSG staff also refurbished the Gaopo Converter Station in Guizhou and Zhaoqing Converter Station in Guangdong, establishing a three-terminal DC system of Luquan-Gaopo-Zhaoqing Converter Stations with a rated capacity of 3 GW.

The project is the first in the world to successfully transform the two-terminal DC into three-terminal one, which makes power transmission more economically viable. It is practical engineering through large-scale power transmission, multi-point connection in receiving ends, grid structure optimization and the safety and stability of the power grid in receiving ends.

China Southern Power Grid engineers on this project have had to overcome major challenges working in areas of high altitude, heavy ice and mountainous karst regions. They made several breakthroughs in the area of power grid technology, including flexible multi-terminal DC transmission and high-altitude DC equipment.

Key equipment including the control and protection system of three-terminal DC and HSS are all products originated by China Southern Power Grid.

The project realizes an independence rate of 100%, which is significant for China to hold key technologies in multi-terminal DC transmission.