Recently, the three inter grid flexible mutual aid projects of Hunan Guizhou, Hunan Guangdong, and Chongqing Guizhou have been officially approved by the state, marking a crucial step towards cross regional power grid interconnection in China. The total investment of the three projects is expected to exceed 15.6 billion yuan, and it is planned to start construction before the end of this year. It will be completed and put into operation before the peak summer of 2027, and the maximum transmission capacity will reach 9 million kilowatts by then.

According to the approval, these three projects will respectively construct a flexible DC back-to-back converter station with a capacity of 3 million kilowatts in Tongren, Guizhou, Chenzhou, Hunan, and Chongqing, and support the construction of related lines. After the completion of the project, the number of transmission channels between Southern Power Grid and State Grid will increase from 2 to 5, significantly enhancing the mutual power supply capacity between the two power grids.

At present, there are two cross regional interconnection projects between State Grid and Southern Power Grid. One is the Three Gorges Guangdong ± 500 kV DC project, which was put into operation in 2004 and mainly undertakes the task of transmitting hydropower from the Three Gorges to the south; The second is the Fujian Guangdong Interconnection Project, which will be completed in 2022 with a transmission capacity of 2 million kilowatts. As of December 15, 2024, 28 power transmission transactions have been completed, with a cumulative transmission capacity of over 10 billion kilowatt hours.

The promotion of the three major interconnection projects coincides with the comprehensive acceleration of the construction of a unified national electricity market. In April of this year, the National Development and Reform Commission and the Energy Administration jointly issued a document proposing to achieve full coverage of the electricity spot market by the end of 2025; In July, a reply was issued regarding the plan for a normalized electricity trading mechanism across power grid operating areas, which clearly stated the need to break market segmentation and regional blockades, and optimize the allocation of electricity resources nationwide.

The relevant person in charge of the Strategic Planning Department of Southern Power Grid pointed out that the new project will effectively leverage the complementary characteristics of electricity between regions. Taking the Hunan Guizhou Project as an example, Hunan has a high electricity load in summer, while Guizhou exhibits a characteristic of "high in winter and low in summer". The two can enhance their supply capacity through peak shaving and mutual assistance. At the same time, the project will significantly enhance the power grid's ability to resist disasters and provide emergency power support in the event of extreme weather conditions.

Data shows that from January to September this year, the total amount of electricity traded across provinces and regions in China reached 1.195 trillion kilowatt hours, a year-on-year increase of 12.1%, which is significantly higher than the growth rate of intra provincial transactions. At a recent press conference of the National Energy Administration, Zhang Yanqin, Deputy Director of the Market Supervision Department, stated that this year, cross provincial and cross regional power resources have achieved large-scale and efficient mutual assistance. Among them, the power transmission during the peak summer season of the Fujian Guangdong interconnection increased by 85% year-on-year, and the southern region achieved power transmission support for the Yangtze River Delta region for the first time. Keywords: infrastructure, engineering construction

With the implementation of the three major interconnection projects, China's power grid will form a more flexible and efficient resource allocation platform, providing solid support for the large-scale consumption of new energy and the construction of a unified national electricity market, and promoting the clean and low-carbon transformation of energy into a new stage.Editor/Cheng Liting