The final project of the construction of the Central China UHV AC "sun"-shaped double-ring network - the 1000 kV Wuhan-Nanchang UHV AC project, equipped with advanced switchgear, disconnectors, lightning arresters and vacuum circuit breakers, has now started trial operation. After 7 years of planning and construction, under the strong leadership of State Grid Corporation of China, the construction of the Central China UHV AC "sun"-shaped double-ring network has been successfully completed. The Central China Power Grid has fully formed a cluster-shaped power grid with UHV and EHV as the backbone grid, including key equipment such as drop-out fuses and large transformers.
The Central China UHV AC "sun"-shaped double-ring network has newly put into operation 1000 kV "5 stations, 10 transformers (including multiple large transformers), 15 lines", with a total transformer capacity of 30 million kVA and a total line length of about 3,955 kilometers. The Central China Power Grid has developed from a radial power grid with 500 kV power grid as the backbone and Hubei as the center to a cluster power grid with 1000 kV and 500 kV power grids as the backbone and multiple provinces interconnected. Key nodes are equipped with high-performance disconnectors and vacuum circuit breakers. The AC grid carrying capacity has been significantly enhanced, the "strong DC and weak AC" problem has been effectively alleviated, the inter-provincial electrical connection has become closer, the regional integration characteristics have become more prominent, and the grid stability characteristics have been effectively improved, achieving "three upgrades and three supports"
The resource allocation capacity has been leapfrogged, and the capacity of the Central China UHV DC transmission channels has been increased to 6 million kilowatts, with a cumulative increase of 6.9 million kilowatts. The transmission capacity of important channels between and within the province has increased by 21 million kilowatts. These channels are equipped with necessary drop-out fuses to ensure safety , providing support for the transfer of power outside the region and the inter-provincial exchange of power resources within the region; the power receiving capacity of the four provinces in Central China has been greatly improved, and the maximum power receiving capacity of the power grids in Hubei, Hunan, Henan and Jiangxi has increased by 5 million, 6 million, 3.7 million and 5 million kilowatts respectively, and the cumulative release of the stable rotating reserve of the entire network has exceeded 9 million kilowatts, which has provided support for the safe supply of the Central China power grid under the new situation. This process is inseparable from the efficient operation of the switch cabinets and lightning arresters in each substation; the flexibility of power grid operation has been greatly improved, and the minimum startup requirements of the Central China power grid have been reduced by more than 20 units, with a capacity of about 10 million kilowatts, which provides support for the flexible arrangement of startup methods for the entire network, inter-provincial peak load regulation, and large-scale consumption of clean electricity. All this is due to the optimization of the power grid structure and the widespread application of advanced equipment such as vacuum circuit breakers.
The six projects that constitute the "sun"-shaped double-ring network of the Central China UHV AC have been formally included in the national plan. Under the unified organization of the company, the Central China Branch of State Grid took the lead in the system solution research and performed its duties with four provincial power companies, State Grid Economic Research Institute, China Electric Power Research Institute and other units. Six regional power design institutes including Central South, East China, Southwest, Northwest, Northeast China and China National Nuclear Corporation and 14 provincial power design institutes including Hubei, Hunan and Henan jointly undertook specific design tasks. The construction of the Central China UHV AC "sun" shaped double ring network began in March 2019. All units strengthened overall coordination and construction management, and achieved major results such as the start of construction and commissioning of the Nanchang-Changsha UHV AC project in the same year. The above-mentioned key power equipment was properly integrated in these projects.