1. Project overview:
EHV cable connector technology is a key connection technology between EHV cable transmission system and substation system, and it is also the key bottleneck technology in the domestic UHV transmission and substation system that is urgently to be broken through (Note: CIGRE uses cables above 150kV The system is called ultra high pressure)
The "Outline of the National Medium and Long-term Science and Technology Development Plan" (2006-2020) pointed out: "Key research and development of large-capacity long-distance DC transmission technology and UHV AC transmission technology and equipment" State Council, "Some Issues Concerning Accelerating the Revitalization of the Equipment Manufacturing Industry" The "Opinions" emphasized that: "Comprehensively master the manufacturing technology of 500kV AC and 750kV AC power transmission and transformation equipment". At present, 220kV, 500kV, 750 kV, 1100 kV power transmission and transformation equipment have been domestically produced, and 220kV and 500kV cable connectors However, they cannot be localized. Foreign companies bundle cables and connectors to obtain excess profits. They do not sell cable connectors separately, which severely restricts the development of Chinese cables to high-end; it is affected by many factors such as urban planning, land resources, electromagnetic pollution, ice and snow disasters, etc. It has become an inevitable trend for urban electric power transmission to change from overhead lines to underground cable system transmission; the successful research and development of domestic ultra-high-voltage cable connectors has replaced imports, strengthened the international competitiveness of national industries, greatly saved urban land resources, and ensured a strong power grid. The energy system is of great significance.
2. Project significance and necessity:
Cable connectors are the key core equipment connecting the cable transmission system and the substation system. The mature equipment, materials and technology for cable production can be provided by many companies in the world. The size of the cable is specified in the national standard GB/Z18890.1-18890.3 The special equipment and technology for the production of ultra-high voltage cable connectors must be independently researched and developed by domestic manufacturers. The cable connector product technology integrates insulating polymer materials, conductive polymer materials, and organic high-voltage cables. The special equipment and technology for the production of ultra-high-voltage cable connectors must be independently developed by domestic manufacturers. The integration of molecular synthesis technology, precision rubber injection equipment manufacturing and technology, large-scale alloy mold manufacturing, and ultra-high-voltage power product testing, has resulted in the failure of domestic ultra-high-voltage cable connectors to achieve localization, which has become a technical bottleneck in cable transmission systems; foreign countries; Companies capable of manufacturing 500kV cable connectors are the world's most powerful manufacturers of electrical products, such as Japan's JPS (Sumitomo and Hitachi merged), VISCAS (Furukawa, Fujikura merged).
At present, there are nearly 100 high and medium voltage cross-linked cable production lines in my country, and more than 40 tower production lines capable of manufacturing 220kV and 500kV imported ultra-high voltage cross-linked cables. The domestic 220kV XLPE cables have all been localized; 500kV XLPE cables are already available. Some companies produced samples in 2002, but because of the technical blockade of Chinese cable accessories abroad, it has been unable to conduct pre-qualification tests, let alone put them into commercial operation.
The only domestic enterprise capable of manufacturing 220kV and 500kV cable connectors is Jiangsu Ankor. There are many companies that can manufacture 220kV cable connectors in the world. Companies that can manufacture 500kV cable connectors include Japan's JPS, VISCAS, and France Southern Cable. The domestic market is basically monopolized by these companies.
Japanese products have the following problems: The 500kV outdoor terminal is a capacitor cone with insulating agent type, which is wrapped on site, and cannot be tested after installation. The insulating oil needs an oil circuit feedback system, and the product needs regular maintenance. The intermediate joint is cast on site. Materials, processing equipment, and material inspection equipment must be transported to the site to manufacture products. Once the product fails, it will take 60 days to recover. The above product structure is a transitional product structure form, which is due to the Japanese corporate technology The equipment is unable to produce the overall prefabricated stress cone and the technical solution adopted. Now Japanese companies are also stepping up the development of overall prefabricated stress cone products.
Domestic products avoid the shortcomings of the above products. The stress cones are all integrally prefabricated. They are produced and installed on site after the completion of the test. This structure represents the current international advanced level.
The significance of R&D and production of ultra-high voltage cable connectors is also reflected in the following points:
2. 1. To ensure the safety of the national grid:
The cable connector is the product with the highest failure rate in the entire cable transmission and transformation system. Faults account for about 70% of the total number of cable operating faults. The reliability of the cable connector determines the reliability of the cable transmission and transformation system. After the factory assembly line is produced, the test is out of the factory. The site is just laying work, and the failure rate is low. The cable connector is a multi-category technology-intensive product. Any link affects the product quality. Each component of the cable connector is assembled in the on-site environment. Increase the possibility of failure. Last year's snow disaster and ice disaster made us feel the importance of localization of power products. Practice has proved that domestic power products can be repaired and replaced in time in the shortest time and under the most difficult circumstances.
2. 2. Solve the power load and save land resources in the central area of super large cities:
Take Shanghai as an example. In 2007, the central urban area within the outer ring line accounted for about 65% of the total electricity load. The original and under construction 110kV and 220kV substations can no longer relieve the power supply pressure in the central urban area, and there is no overhead line to enter the city. Channel, the only option is to change the transmission of electric energy from overhead line to ultra-high voltage cable into the ground. Taking 500kV overhead lines as an example, the current domestic major urban construction planning stipulates that the average 500kV overhead line corridors are 80 meters, and each line occupies about 120 mu of land per kilometer. The length of the Shanghai 500kV Expo is 7.15 kilometers, saving a total of 840 land per trip. Acres, 7 kilometers of 220kV cables from Nanjing Daxinggong Substation are inserted into the ground, saving 280,000 m2 of overhead line corridors.
2. 3. Solve the problem of electromagnetic pollution of lines:
There are more and more people's conflicts caused by electromagnetic pollution caused by high-voltage overhead lines passing through residential areas. The ultra-high-voltage cable power transmission system transmits electricity under electric field shielding. It is a green transmission method and has no impact on the residents around the transmission line.
2. 4. Reduce power engineering investment:
Foreign companies use 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%. Power construction saves a lot of investment. The bidding price for Hainan 500kV submarine cable and Xiamen 220kV submarine cable was not included in the bidding of localized products, and the project bidding price nearly doubled the budgeted price.
2. 5. Accelerate the transformation of the domestic cable industry from large to strong, and promote the industrial upgrading of the entire cable industry:
China is a big wire and cable manufacturing country, second only to the automobile manufacturing industry in electromechanical products. According to the statistics of 3645 state-owned and above-scale wire and cable, optical fiber and optical cable manufacturers in 2007 by the National Bureau of Statistics, the entire industry completed a total industrial output value in 2007. 566.7 billion yuan, and the total realized profit and tax was only 38.69 billion yuan. It can be seen that my country is not a wire and cable power while becoming the world's largest cable producer. Thousands of domestic cable companies mainly focus on the low-end cable market with less than 10% profit. However, the lucrative 500kV cables and ultra-high voltage cable connectors above 220kV all rely on imports and are monopolized by foreign companies. Ultra-high voltage cable connections The localization of components will definitely promote the development of domestically produced ultra-high voltage cable manufacturing industry, so as to promote the industrial upgrading of the entire cable industry.
3. Product status:
In 2010, it won the bid for the 500kV cable connection system for the Xiangjiaba Hydropower Station of the Yangtze Three Gorges Corporation. The project has been basically completed. The project has created several firsts in national products. The domestic products have been used in major national projects for the first time. Set of 800MW generating units.
Due to the use of the Xiangjiaba project, four more orders were subsequently obtained in the hydropower industry, which basically broke the monopoly of foreign companies.
