Nanyang-Jingmen-Changsha ultra-high voltage improves the safety level of the central China power grid

The "Environmental Impact Report on the Nanyang-Jingmen-Changsha 1000kV UHV AC Transmission and Transformation Project" (Draft for Review) (hereinafter referred to as the "Draft for Review") recently released by State Grid Corporation of China revealed that the project is an important part of the Central China UHV AC ring network, which meets the requirements for safe and stable operation of the Central China power grid after multiple DC feeds, and ensures that when a bipolar lockout fault occurs in any UHV DC in the region, the power grids of relevant provinces do not need to take measures, and the system can maintain safe and stable operation.

At the same time, the Nanyang-Jingmen-Changsha ultra-high voltage AC project can strengthen the power grid connection among the four provinces in central China (Henan, Hunan, Hubei, and Jiangxi), improve the power receiving capacity of the AC sections in each province, build a platform for optimizing the allocation of power resources, and create conditions for the segmented operation of the 500 kV power grid, avoiding the need to take a large number of measures to weaken the power grid structure due to the control of short-circuit current levels, thus reserving a certain space for the development of the power grid.

In addition, the draft for review also shows that after the completion and commissioning of the Central China UHV AC ring network, it can effectively solve the dynamic stability problem of the Hunan-Henan power grid under the hedging mode, improve the section transmission capacity, and solve the water abandonment problem. Combined with the long-term UHV planning, the construction of the Nanyang-Jingmen-Changsha UHV AC project will open up a new channel for Hunan to receive the Ya'an-Zhongshan UHV DC agreement power distribution, meeting the load development needs of Hunan, especially the eastern part of Xiangdong.

According to the draft for review, the Nanyang-Jingmen-Changsha high-voltage AC project will build a new 1,000 kV substation in Changsha, expand the 1,000 kV substation in Jingmen, and build 288 kilometers of new Nanyang-Jingmen 1,000 kV AC transmission lines and 2×336 kilometers of Jingmen-Changsha 1,000 kV AC transmission lines, involving Nanyang City in Henan Province, Xiangyang City, Jingmen City, Qianjiang City, Jingzhou City in Hubei Province, and Yueyang City and Changsha City in Hunan Province, a total of 3 provinces, 7 cities and 18 counties (urban areas).

It is understood that the world's first UHV AC project in operation - the Southeast Shanxi-Nanyang-Jingmen 1,000 kV UHV AC project is a single-circuit project that has covered Nanyang and Jingmen; the Nanyang-Jingmen-Changsha UHV AC project's newly built Nanyang-Jingmen transmission line is a single-circuit project, and the newly built Jingmen-Changsha transmission line is a double-circuit project.

According to the "Notice on Accelerating the Planning and Construction of a Batch of Key Power Transmission and Transformation Projects" issued by the National Energy Administration in September 2018, the Nanyang-Jingmen-Changsha UHV AC project will form a "sun"-shaped Central China UHV AC ring network covering Nanyang, Zhumadian, Wuhan, Jingmen, Nanchang and Changsha with the Zhumadian-Nanyang, Zhumadian-Wuhan, Wuhan-Jingmen, Wuhan-Nanchang, Nanchang-Changsha and Southeast Shanxi-Nanyang-Jingmen UHV AC projects.

Among them, the Zhumadian-Nanyang UHV AC project is under construction. At the same time, according to the "2020 UHV and Inter-provincial 500 kV and Above AC and DC Project Preliminary Work Plan" compiled by the State Grid, other projects of the Central China UHV AC ring network - Nanchang-Changsha, Wuhan-Jingmen, Zhumadian-Wuhan, Wuhan-Nanchang 4 UHV AC projects are planned to be approved in June, September, October and December this year respectively.