1. Project Overview:
Ultra-high voltage cable connection technology is a key connection technology between ultra-high voltage cable transmission system and power transformation system, and it is also a key bottleneck technology that needs to be broken through in the domestic ultra-high voltage transmission and transformation system (Note: CIGRE refers to cable systems above 150kV as ultra-high voltage)
The "Outline of the National Medium and Long-term Science and Technology Development Plan" (2006-2020) pointed out: "Focus on the research and development of large-capacity long-distance DC transmission technology and UHV AC transmission technology and equipment" The State Council, "Several Opinions on Accelerating the Revitalization of Equipment Manufacturing Industry" focuses on: "Fully master the manufacturing technology of 500kV AC DC and 750kV AC transmission and transformation equipment", and at present, 220kV, 500kV, 750 kV, 1100 kV power transmission and transformation equipment have been localized 220kV and 500kV cable connectors cannot be localized, and foreign enterprises bundle and sell cables and connectors to obtain excess profits, and do not sell cable connectors separately, which seriously restricts the development of China's cables to the high-end; Constrained by many factors such as urban planning, land resources, electromagnetic pollution, ice and snow disasters, urban electric energy transmission has become an inevitable trend from overhead lines to underground cable system transmission. The successful research and development of domestic ultra-high voltage cable connectors is of great significance to replacing imports, enhancing the international competitiveness of national industries, saving a large amount of urban land resources, and ensuring a strong power grid and energy system.
2. Project significance and necessity:
Cable connection is the key core equipment of cable transmission system and substation system connection, cable production mature equipment, materials, technology can be provided by many enterprises in the world, the size of the cable is the national standard GB/Z18890.1-18890.3 stipulated, in the factory assembly line production; The cable connector product technology integrates insulating polymer materials, conductive polymer materials, organic polymer synthesis technology, precision rubber injection equipment manufacturing and technology, large alloy mold manufacturing, ultra-high voltage power product testing and other technologies, resulting in domestic ultra-high voltage cable connectors can not be localized, becoming a technical bottleneck in the cable transmission system; Foreign companies that can manufacture 500kV cable connectors are the world's most powerful manufacturers of electrical products, such as Japan's JPS Corporation (Sumitomo and Hitachi merger) and VISCAS Corporation (Furukawa, Fujikura merger).
35kV cold shrink cable accessory
At present, there are nearly 100 production lines of high- and medium-voltage cross-linked cables in China, and more than 40 vertical tower production lines capable of manufacturing 220kV and 500kV imported ultra-high voltage cross-linked cables, and all domestic 220kV XLPE cables have been localized; 500kV XLPE cable has been manufactured by enterprises as early as 2002, but because of the technical blockade of Chinese cable accessories abroad, it has not been possible to carry out pre-qualification tests, let alone put into commercial operation.
The only domestic enterprise that can manufacture 220kV and 500kV cable connectors is Jiangsu Anko. There are many enterprises that can manufacture 220kV cable connectors internationally, and the companies that can manufacture 500kV cable connectors are JPS, VISCAS, and French Southern Cable in Japan, and the domestic market is basically monopolized by these enterprises.
Japanese products have the following problems: 500kV outdoor terminal for capacitive cone plus insulating agent type, on-site wrapping, can not be tested after installation, insulating oil needs oil feedback system, products need regular maintenance. The middle and indirect head is on-site casting type, to transport materials, processing equipment, material inspection equipment to the site to manufacture products, once the product failure to 60 days to recover, the above product structure is a transitional product structure form, by the Japanese enterprise process and equipment can not produce the overall prefabricated stress cone and adopt the technical solution, now Japanese enterprises are also stepping up the development of the overall prefabricated stress cone products.
Domestic products avoid the shortcomings of the above products, stress cone is all integral prefabricated type, in the factory production, after the completion of the test to the site installation, the structure represents the current international most advanced level.
The significance of developing and producing ultra-high voltage cable connectors is also reflected in the following points:
2. 1. Ensure the security of the State Grid:
Cable connector is the whole cable transmission and transformation system in the highest failure rate of a product, failure accounts for about 70% of the total number of cable operation failures, the reliability of cable connection determines the reliability of the cable transmission and transformation system, because the cable in the factory assembly line production after the test factory, the site is only laying work, the failure rate is low, cable connection is a multi-category technology-intensive product, any link affects product quality, cable connection each component to the site environment assembly, increase the possibility of failure. Last year's snow and ice disasters made us feel even more the importance of localizing power products, and practice has proved that domestic power products can be repaired and replaced in a timely manner in the shortest time and under the most difficult circumstances.
2. 2. Solve the electricity load and save land resources in the central area of the super large city:
Taking Shanghai as an example, in 2007, the electricity load of the central urban area within the outer ring road accounted for about 65% of the total, and the 110kV and 220kV substations that were originally and under construction could no longer relieve the power supply pressure in the central urban area, there was no passage for overhead lines to enter the city, and the power transmission was changed from overhead line transmission to ultra-high-voltage cable to ground transmission. Taking the 500kV overhead line as an example, now the main urban construction planning in China stipulates that the average 500kV overhead line corridor is 80 meters, each line occupies about 120 mu of land per kilometer, the length of the Shanghai 500kV Expo is 7.15 kilometers, a total of 840 mu of land is saved in a single turn, and the 220kV cable enters the ground for 7 kilometers of Nanjing Daxinggong substation, saving 280,000 m2 of the overhead line corridor.
2. 3. Solve the problem of electromagnetic pollution of the line:
The high-voltage overhead line crosses the residential area due to the problem of electromagnetic pollution caused by more and more contradictions, ultra-high voltage cable transmission system in the electric field shielded state of power transmission, is a green transmission method, has no impact on the body of residents around the transmission line.
2. 4. Reduce investment in power engineering:
Foreign enterprises take advantage of the existing monopoly position to obtain excess profits, when the 500kV cable connection system is localized, the entire cable project cost will be reduced by 40%, when the 220kV cable connection system is localized, the entire cable project cost will be reduced by 30%, saving a lot of investment for national power construction. Since there were no domestic products involved, the bidding price of the project exceeded the budget price by nearly double.
2. 5. Accelerate the transformation of the domestic cable industry from large to strong, and enhance the industrial upgrading of the entire cable industry:
China is a large cable manufacturing country, second only to the automobile manufacturing industry in mechanical and electrical products, according to the National Bureau of Statistics in 2007 for 3645 state-owned and above the scale of wire and cable, optical fiber and cable production statistics, in 2007 the entire industry completed a total industrial output value of 566.7 billion yuan, the total profit and tax is only 38.69 billion yuan, it can be seen that China has become the world's largest cable producer at the same time, is not a wire and cable power. Thousands of domestic local cable companies mainly around the profit of less than 10% of the low-end cable market to fight, while the lucrative 500kV cable and more than 220kV ultra-high voltage cable connectors are all imported, monopolized by foreign investors, the localization of ultra-high voltage cable connectors will effectively promote the development of domestic ultra-high voltage cable manufacturing industry, in order to enhance the industrial upgrading of the entire cable industry.
3. Product status:
In 2010, it won the bid for the 500kV cable connection system of Xiangjiaba Hydropower Station of Yangtze River Three Gorges Corporation, and now the project has been basically completed, the project has created several firsts of domestic products, and domestic products are used in major national projects for the first time, with the world's first 800MW unit.
Due to the use of the Xiangjiaba project, 4 more orders were subsequently obtained in the hydropower industry, basically breaking the monopoly of foreign enterprises.
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