Necessity of Construction of UHV Network Needs to be Known

Uhv network refers to 1000kV and above AC power grid or ±800kV and above DC power grid. The transmission voltage is generally divided into high voltage, extra high voltage and ultra high voltage. Internationally, high voltage (HV) usually refers to the voltage of 35~220kV; extra high voltage (EHV) usually refers to the voltage of 330kV and above and below 1000kV; ultra high voltage (UHV) refers to the voltage of 1000kV and above. High-voltage direct current (HVDC) generally refers to DC transmission voltages of ±600kV and below, and voltages of ±800 kV and above are called ultra-high voltage direct current transmission (UHVDC).


UHV Network


The Uhv network has long distance, large capacity, low loss, and less land occupation, and its transmission capacity can reach 2.4 to 5 times that of 500 kV EHV transmission. Known as the "Electric Highway".


On July 8, 2010, the Xiangjiaba-Shanghai ±800 kV UHVDC demonstration project independently developed, designed and constructed by China was officially put into operation. It is the DC transmission project with the highest voltage level, the largest transmission capacity and the longest transmission distance in the world.


On December 16, 2011, the world's first commercially operated UHV AC power transmission project (1000 kV Jindongnan-Nanyang-Jingmen UHV AC test demonstration project) was officially put into operation in China.


1. Introduction to Uhv network


For the vast majority of power grids in my country, high-voltage power grids refer to 110kV and 220kV power grids; ultra-high voltage power grids refer to 330kV, 500kV and 750kV power grids. UHV transmission refers to the 1000 kV AC voltage and ±800kV DC voltage transmission projects and technologies under development. Uhv network refers to a layered, partitioned and clearly structured modern large power grid composed of 1000kV transmission network as the backbone grid, EHV transmission network, high voltage transmission network, UHV DC transmission, HVDC transmission and distribution network.


The basic conditions for the formation and development of Uhv networks are the continuous growth of electricity load, and the construction and development of large-capacity and extra-large-capacity power plants, whose outstanding features are large-capacity and long-distance power transmission. China's long-distance power transmission, like other countries in the world, mainly uses 500 kV AC power grids. Only a small number of 1000 kV AC lines in Russia, Japan, and Italy operate at reduced voltage.


2. National planning of Uhv network


UHV power transmission "Twelfth Five-Year" plan

The State Grid Corporation proposed in the "Twelfth Five-Year Plan" that in the future, my country will build a "three vertical and three horizontal" UHV backbone grids connecting large energy bases and main load centers and 13 DC transmission projects (including 10 UHV DC projects) ), forming a large-scale energy allocation pattern of "power transmission from west to east" and "power transmission from north to south". By 2015, a strong smart grid with the Uhv network as the backbone grid, coordinated development of power grids at all levels, and characteristics of informatization, automation, and interaction will be basically completed, forming "three Chinas" (North China, Central China, East China), Northwest, The three major synchronous power grids in Northeast China have comprehensively improved the resource allocation capability, economic operation efficiency, safety level, technological level and intelligent level of the State Grid.


3. Significance of construction of Uhv network


construction necessity

The biggest feature is that it can transmit power over long distances, large capacity, and low loss. According to estimates, the transmission capacity of 1,000 kV AC UHV transmission lines exceeds 5 million kilowatts, which is nearly five times that of 500 kV UHV AC transmission lines. The transmission capacity of ±800 kV DC UHV reaches 7 million kilowatts, which is 2.4 times the transmission capacity of ±500 kV EHV DC lines.


76% of my country's coal resources are distributed in the north and northwest; 80% of water energy resources are distributed in the southwest; most land wind and solar resources are distributed in the northwest. At the same time, more than 70% of the energy demand is concentrated in the eastern and central regions. The distance between the energy base and the load center is 1,000 to 3,000 kilometers.


Large-scale power supply construction in the load center area will obviously be subject to various constraints. Such as coal transportation issues, environmental capacity issues and so on. Moreover, the construction of thermal power can also rely on coal transportation, and hydropower and wind power cannot be realized because it is impossible to transport water and wind like coal. On the one hand, it is impossible to build power points on a large scale, and on the other hand, it is impossible to build large-scale power sources in load centers.


First of all, from the perspective of optimal allocation of resources, as my country's energy strategy moves westward, the distance between large energy bases and energy consumption centers is getting farther and farther, and the scale of energy transmission will also become larger and larger. On the basis of traditional transportation methods such as railways, highways, shipping, and pipelines, improving the transportation capacity of the power grid is also an option to alleviate transportation pressure. Take the 1,000-kilovolt UHV demonstration project that has been put into operation as an example. It can transmit 2 million kilowatts of electricity per day, and it can reach 5 million kilowatts after transformation. This is equivalent to transporting 25,000 to 60,000 tons of raw coal from Shanxi to Hubei every day. Hubei media said that this is equivalent to "sending" a Gezhouba power station to Hubei.


Looking at the economic benefits, the price of thermal coal in the western and northern regions is 200 yuan/ton of standard coal. The coal is loaded from the local area, transported to Qinhuangdao Port by road and rail, and then transported to East China by sea and road. The price of thermal coal increases to more than 1,000 yuan/ton of standard coal. After conversion, the fuel cost per kWh of electricity alone reaches about 0.3 yuan. However, when building a pithead power station in a coal production area, the fuel cost is only 0.09 yuan/kWh. The electricity from the Kengkou Power Station is transmitted to the central and eastern load centers through UHV. After deducting the cost of the transmission link, the grid electricity price is still 0.06-0.13 yuan/kWh lower than the average grid electricity price of local coal power.


UHV is the necessary support for the development of clean energy. Only UHV can solve the problem of large-scale consumption of clean energy power generation. Some time ago, Inner Mongolia's wind power "basking in the sun" has attracted widespread attention. In fact, my country's wind power is mainly concentrated in the "Three North" regions, and the local consumption space is very limited. The further development of wind power objectively needs to expand the scope of wind power consumption. Large wind power must be integrated into the large power grid. A strong large power grid can significantly improve the capacity of wind power consumption. The Uhv network will constitute a large-capacity, long-distance energy transmission channel in my country. According to estimates, if wind power is only consumed in the province, the scale of wind power that can be developed nationwide in 2020 will be about 50 million kilowatts. And through UHV cross-regional network transmission to expand the consumption capacity of clean energy, the national wind power development scale can reach more than 100 million kilowatts.


First, promote the development of scientific and technological innovation UHV is a major scientific and technological innovation project. At the beginning of the conception and full launch, the company invested huge sums of money to build four world-class UHV AC, DC, high-altitude, and engineering mechanics. The base and the two R&D centers of large power grid simulation and DC complete set design have formed a large power grid experimental research system with complete functions and comprehensive indicators ranking at the world's leading level. In the past few years, the State Grid Corporation has completed 310 major key technology researches around the UHV project, and solved many world problems such as overvoltage and insulation coordination, external insulation design, electromagnetic environment control, system integration, and safe operation control of large power grids. Gradually mastered the key core technologies of UHV power transmission and successfully applied them in experimental projects.


Second, UHV construction has a more obvious driving effect on the domestic equipment manufacturing industry. Almost all the equipment used in the three major UHV experimental projects in China is provided by domestic enterprises, the localization rate of the projects has reached about 95%, and the localization rate of the equipment has reached about 91%. Through the experimental project, domestic equipment manufacturing enterprises have been tempered, and their scientific and technological research and development capabilities have been greatly improved. For example, Nantong Shenma Electric Power Technology Co., Ltd. has successfully overcome the world problem of UHV insulators. Ma Bin, chairman of the company, said that the performance of the world's first UHV 1000 kV hollow composite insulator, which we invested nearly 100 million yuan in research and development, has reached the international leading level, while the price is only 1/3 of foreign products.


Studies have shown that the natural transmission power of a 1000 kV AC line is about 5 times that of a 500 kV line. Under the same conditions, the resistance loss of a 1000 kV AC line is only 1/4 of that of a 500 kV line, the corridor width per unit transmission capacity is only 1/3 of that of a 500 kV line, and the comprehensive cost per unit transmission capacity is less than 500 kV transmission scheme 3/4 of.


4. Key projects of Uhv network


Cases of key projects in Uhv network industry

This project is my country's first UHV transmission line, and it is also an AC power transmission project with the highest operating voltage and the most advanced technology in the world. The line has a total length of 654 kilometers and a static investment of about 5.7 billion yuan. It started construction in August 2006 and was put into commercial operation in January 2009. After more than a year of trial operation, in August 2010, the UHV AC transmission test demonstration project passed the national acceptance. This marks that the UHV AC transmission project has entered the large-scale construction stage from the demonstration stage.


This project is an AC transmission project with the highest voltage level, the largest transmission capacity, the longest transmission distance and the most advanced technology in the world independently researched and developed, designed and constructed by my country. The project was approved on April 26, 2007 and put into operation on December 16, 2011.


5. Memorabilia of Uhv network


On August 9, 2006, the National Development and Reform Commission issued the "Reply on the Approval of the UHV AC Test and Demonstration Project from Southeast Shanxi to Jingmen" (Fagai Nengli [2006] No. 1585), officially approved the High-voltage AC test demonstration project. According to the State Grid Corporation of China, the UHV line has a total length of 654 kilometers, a declared cost of 5.857 billion yuan, and a dynamic investment of 20 billion yuan. It starts from Changzhi Substation in Shanxi Province, passes through Nanyang Switching Station in Henan Province, and ends at Jingmen Substation in Hubei Province. If it is fully rolled out across the country, the future investment will be more than 406 billion yuan, and the supporting dynamic investment will reach more than 800 billion yuan. The total investment is equivalent to 3 to 4 Yangtze River Three Gorges projects. This huge project has not been included in the outline of the national "Eleventh Five-Year Plan".


According to the "Memorabilia of the UHV Project" published by the State Grid Corporation, the idea of "building a strong national grid with UHV as the core" was first proposed at the Party Group Meeting of the State Grid Corporation on December 27, 2004. It took less than 20 months from conception to approval by the National Development and Reform Commission. From August 19th to 26th, the UHV test project was grandly laid in Changzhi, Shanxi, Nanyang, Henan, and Jingmen, Hubei. On October 30, the State Grid Corporation of China held an oath mobilization meeting for the construction of the Jindongnan-Nanyang-Jingmen 1000 kV UHV AC test project in Shanxi, Henan and Hubei.


According to the plan of the State Grid Corporation of China, in 2015, the "Sanhua" Uhv network will form a "three vertical, three horizontal and one ring network". The 3 vertical transmission channels are Ximeng~Beijing East~Tianjin South~Jinan~Xuzhou~Nanjing, Zhangbei~Beijing West~Shijiazhuang~Yunbei~Zhumadian~Wuhan~Nanchang, Northern Shaanxi (West Meng)~Jinzhong~Jin Southeast ~ Nanyang ~ Jingmen ~ Changsha. The 3 horizontal power transmission channels are: West Mengxi~Northern Jin~Shijiazhuang~Jinan~Weifang, Jingbian~Jinzhong~North Henan~Xuzhou~Lianyungang, Ya'an~Leshan~Chongqing~Changshou~Wanxian~Jingmen~Wuhan~Wannan~Zhejiang North to Shanghai. The UHV double-loop network is: Huainan~Nanjing~Taizhou~Suzhou~Shanghai~Northern Zhejiang~Southern Anhui~Huainan Yangtze River Delta.


6. Development of Uhv network


In the world, only a few countries such as Russia and Japan have carried out the test operation of UHV AC transmission technology. The largest project of DC transmission that has been completed and put into operation is Brazil’s Itaipu Transmission Project, which includes two circuits of ±600 kV voltage level and 3.6 million kilowatts. A dc line of rated power delivery. UHV power transmission technology is still a cutting-edge technology that has yet to mature in the world, and its key core technology, reliability, and impact on the environment still need further research. The unbalanced distribution of energy resources and productivity in our country urgently needs to solve the problem of long-distance transmission of electric energy. The adoption of UHV transmission technology will effectively increase the transmission distance, increase the transmission capacity, reduce transmission loss, reduce transmission costs, and achieve a wider range of optimal allocation of resources. The state attaches great importance to China's UHV power transmission project, and has made it clear that the work related to the construction of China's Uhv network should be carried out in accordance with the principles of "scientific demonstration, demonstration first, independent innovation, and accelerated advancement".


The large-scale construction of domestic power grid projects and the design, manufacture and technology introduction of ultra-high voltage power transmission and transformation equipment have laid a good foundation for the development and use of UHV technology and equipment in China. At present, China has met certain conditions for independent innovation, independent research and independent development of UHV transmission technology. Approved by the state, the State Grid Corporation of China has started the construction of the Jindongnan-Jingmen AC 1000 kV UHV test demonstration project and the Xiluodu and Xiangjiaba transmission ±800 kV, 6.4 million kW DC UHV transmission localization demonstration projects. China Southern Power Grid Corporation also The preliminary construction work of the localization demonstration project of ±800 kV and 5 million kW DC UHV transmission from Chuxiong, Yunnan to Suidong, Guangzhou has started.

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