Recently, the State Grid Corporation of China carried out the asynchronous operation test of the Southwest Power Grid, and verified the effectiveness of the network-to-asynchronous operation capability of the Southwest Power Grid and the ultra-low frequency oscillation suppression measures. It laid the foundation for the commissioning of the back-to-back project and the asynchronous safe and stable operation of the Southwest Power Grid at the end of the year. Previously, Yunnan Power Grid and China Southern Power Grid's main network have realized asynchronous interconnection through the Luxi back-to-back project. This is the first asynchronous interconnection between China's provincial-level power grid and large-area power grid, which is a useful exploration to ensure the safe and stable delivery of Southwest Hydropower.
Up to now, Sichuan Hydropower has formed a “four straight and eight crosses†delivery channel, namely ±800 kV Fufeng, Jinsu, Binjin, three UHV DC transmission lines and ±500 kV Debao DC, and Sichuan - Chongqing 6 back 500 kV AC line and Sichuan-Tibet networking project (two times), UHV "strong and weak contact" features highlighted. In order to effectively reduce the structural risks brought about by the UHV "strong and weak contact", simplify the grid security and stability control strategy, and improve the flexibility and reliability of the grid operation, the State Grid started construction of the back-to-back project in May 2017.
According to relevant plans, the project will be put into operation at the end of 2018. By then, the Sichuan-Yunnan power grid and the four provinces in the Middle East will realize asynchronous interconnection, and the national network structure will be further optimized. A key step in the construction of the Southwest Power Grid can be fundamentally solved. The stability problem of the 500 kV cross-zone long-chain power grid. At the same time, it will increase the power transmission capacity of the Yu-E section from 2.6 million kilowatts to 5 million kilowatts, greatly improving the mutual economic capability between the Sichuan-Yunnan power grid and the eastern China power grid, which will help alleviate the contradiction of “abandonment of water†and promote the development of southwest hydropower and Size delivery.
“Construction of the back-to-back project of the E-European is of great significance for promoting the sustainable development of China's electric power and energy.†Relevant persons of the State Grid have previously stated that “Asynchronous networking of the Southwest Power Grid is a major factor in optimizing the grid structure, ensuring energy supply security, and promoting energy conservation and emission reduction. Initiative."
Back-to-back engineering using straight and straight technologyIt is understood that, similar to the situation in Sichuan, with the continuous development of Yunnan hydropower, China Southern Power Grid Corporation has accelerated the implementation of the West-East Power Transmission. Up to now, Yunnan has built a “two-way and eight-right†channel to send electricity to Guangdong and Guangxi. The maximum transmission distance is 1438 kilometers, and the maximum power transmission capacity is 28.65 million kilowatts. With the northwestern Yunnan high-voltage direct current transmission project, it will be fully completed at the end of June this year. After putting into production, the maximum capacity of the cloud power transmission channel can be increased by 5 million kilowatts. As the distance between the east and west AC power grids is getting farther and farther, the AC/DC hybrid power grid structure is becoming more and more complex, and the risk of multiple DC simultaneous blocking or successive blocking faults increases, posing a threat to the overall safe and stable operation of the South Network.
The research results show that the asynchronous connection between the main network of Yunnan Power Grid and the main network of South Network can effectively solve the problem of grid security and stability caused by AC/DC power transfer, simplify the security and stability control strategy of power grids under complex faults, avoid large-area power outage risks, and greatly increase The safe power supply reliability of the main grid of the South Network. To this end, in June 2016, Nanwang Construction put into operation the Luxi back-to-back project. One year later, in June 2017, the expansion project of the Luxi back-to-back converter station was put into operation. Practice has proved that since the project was put into operation, it has effectively improved the safe and stable operation capability of the main grid of the South Network and promoted the consumption of clean energy.
The reporter found out that whether it is the Luxi back-to-back project or the back-to-back project of the Yi-E, the flexible DC plus conventional DC combination mode is adopted. Among them, the Luxi back-to-back project uses a voltage of ±350 kV and a unit capacity of 1 million kilowatts. Straight technology, the back-to-back project in Jian'an under construction will use a straightening technology with a voltage of ±420 kV and a unit capacity of 1.25 million kilowatts. The reason why the two projects adopt the soft-straight technology is mainly because the technology has strong advantages in the interconnection of the communication system, and is a strategic choice to change the development pattern of the large power grid.
Laying the foundation for the construction of the western power gridAs we all know, the southwest region is an important energy base in China, with abundant water resources and various forms of energy such as geothermal, solar energy and wind energy. In particular, water energy is both clean energy and renewable energy, and its large-scale technology is fully mature. To this end, in November 2014, the State Grid proposed the scientific deployment of the Southwest Grid consisting of Sichuan-Tibet Grid and the strategic deployment of the National Grid Bureau, and established the Southwest Branch of the State Grid.
According to relevant plans, during the “Thirteenth Five-Year Plan†period, the State Grid will form two synchronous grids. Among them, the eastern synchronous power grid is formed by the “Sanhua†and the northeast through UHV AC networking. The western synchronous power grid is formed by the UHV and Sichuan-Tibet reservoirs through UHV AC networking. The structure of the transmission and receiving ends is clear, and the communication and DC are coordinated. Up to now, the Sichuan-Tibet-Tibet Power Grid has initially formed the Southwest Power Grid through the Sichuan-Tibet network and the Sichuan-Yunnan network. The construction of the back-to-back project will lay the foundation for the construction of the southwest transmission network.
At the same time, with the completion of the Tibet-China Network this year, the Qinghai-Tibet Network will be interconnected with Sichuan and Tibet, and then interconnected with Qinghai and Sichuan Power Grids. The interconnection of different resource types in the southwest and northwest will be strengthened, and the power grid structure in the central and eastern regions of Tibet will be significantly enhanced. During the dry season in winter, the power supply is tight and contradictory, which greatly improves the safe and reliable power supply capacity of the power grid, laying a solid foundation for the subsequent transportation of electricity.
Obviously, the Southwest Power Grid, which only includes the Sichuan-Yunnan Grid, is not entirely worthy of its name. In this regard, Cao Zhian, the general manager of the South Network, introduced this year's national "two sessions": "The research will promote the interconnection and interconnection of Yunnan and Guizhou power grids, promote the mutual access of the South Network and the national network, and expand the scale of power mutual aid." This is consistent with the “Notice on Promoting Hydropower Consumption in Southwest China†issued by the National Development and Reform Commission and the National Energy Administration.
It can be seen that perhaps in the near future, the Sichuan-Chongqing-Southwest Power Grid in the State Grid's operation area will form a large southwest power grid with water and electricity transmission from Yunnan and Guizhou power grids in the South Network operation area. This southwest power grid and the central and eastern load areas will be interconnected asynchronously through the back-to-back and back-to-back projects of Luxi to ensure safe and stable operation of the transmission and receiving power grids. At the same time, the Southwest Power Grid will form a large western transmission grid with the current Northwest Power Grid in the State Grid's operating area to achieve water, fire, wind and light.
Camera Filter,Camera Polarizer Lens,Camera Raw Filter,Lens Filter
Shaoxing Shangyu Kenuo Photographic Equipment Factory , https://www.kernelphoto.com