Flexible DC cable promising Zhongtian technology EHV DC cable technology among the world's first camp

At present, fossil fuels are gradually depleted and environmental problems are getting worse. Under the impetus of many factors, energy transformation has become an issue of international hot topics. The development and utilization of clean energy has become a consensus, the distributed energy near the client gradually began to start a prairie fire. The construction of a global energy Internet is imminent. All of these require more power transmission means with higher transmission distance, higher performance and more flexible control. Therefore, High voltage level, large capacity flexible DC transmission technology has been favored.

Recently, transit technology held a news conference to announce: the world's largest transmission capacity, China's first ± 525kV XLPE insulated flexible DC cable system was successfully developed. The success of Zhongtian not only marks that China's EHV DC cable technology ranks among the first in the world, but also provides more possibilities for China's energy transformation and development. It provides a brand new solution for transforming transmission modes and building the future power grid.

Flexible DC cable

Flexible DC transmission into the future direction of power grid development

The flexible DC transmission technology is a new type of DC transmission developed in the 1990s. It applies advanced power electronics technology to provide flexible control measures for the power grid, upgrades the semi-control power electronic devices into full-control power electronic devices, Fast response, good controllability, flexible operation.

With the advent of the first flexible HVDC transmission project in 1997, the research on flexible HVDC transmission in the world has been in a very active state. Although the research on flexible DC transmission technology in China started relatively late, it developed rapidly.

In 2011, the construction of Shanghai Nanhui Wind Farm Flexible DC Transmission Project by Shanghai Electric Power Company was put into operation. This is the first soft project with independent intellectual property rights in Asia. The DC voltage is ± 30 kV and the converter station capacity is 18 MW.

In 2013, the ± 160kV multi-terminal flexible DC transmission demonstration project in Nanao, Guangdong put into operation. This project overcomes the world challenge of multi-terminal flexible DC transmission control and protection, and makes China the first in the world to have a complete set of design, construction, Debug and run a full range of core technology, the world's transmission technology at the forefront.

In 2014, SGCC built the world's first five-terminal flexible DC transmission project in Zhoushan, Zhejiang Province. Using ± 200 kV DC voltage, a converter station was set up in Dinghai, Daishan, Qushan, Yangshan and Sijiao, respectively, to achieve Multiple offshore wind farms simultaneously access and deliver power.

In 2015, the world's first bipolar flexible DC transmission project - Xiamen ± 320 kV flexible DC transmission technology demonstration project was put into operation, marking a comprehensive grasp of China's high-voltage large capacity flexible HVDC transmission key technologies and engineering capabilities to achieve International leader in flexible DC transmission technology. The project is based on the application of ± 200 kV flexible DC project in Zhoushan, Zhejiang Province. The voltage level was first raised to ± 320 kV from the bipolar junction to the true bipolar junction.

From Nanhui wind farm in Shanghai to Nan'ao Island in Shantou, Guangdong Province, from Zhoushan Weizhin at Zhejiang Zhoushan to Xiamen with 320kV dipole flexibility, it indicates that China has fully mastered the key technologies and engineering capabilities of high-voltage large capacity flexible HVDC and our flexible HVDC is rapidly being practiced and explored in many research fields such as high voltage, large capacity, multi-terminal, bipolar and so on, and flexible DC transmission technology has become an important development direction of future power grids.

China's UHV DC cable technology among the world's first camp

China's flexible DC transmission technology has entered a rapid development stage, at the same time, turn-off devices, DC cable manufacturing level has also reached a new level.

In recent years, China's ultra-high voltage technology continues to go abroad and gain recognition in the international market. At the same time, ultra- and ultra-high voltage key equipment manufacturing technology is still in the hands of foreign giants, especially the DC transmission technology, which China urgently needs Breakthrough in the development of DC cable technology bottlenecks.

The world's largest transmission capacity, the success of China's first ± 525kV XLPE insulated flexible DC cable system, is the success of Zhongtian Science and Technology Co., Ltd. Following the successful development of ± 160kV, ± 200kV and ± 320kV DC cables and 500kV AC submarine cables Breakthrough innovation also marks China's UHV DC cable technology and Europe, Japan and other developed countries in the same advanced level.

Jiangsu Zhongtian Science and Technology Co., Ltd. (hereinafter referred to as Zhongtian Science and Technology) is one of the Top 500 Chinese Enterprises and Top 100 Listed Companies on the Main Board of China. Since its establishment in the optical fiber communications industry, with the rapid development of the national information industry and after two industrial restructurings, The formation of communications, electricity, new energy sources, marine systems, new materials and Seiko equipment and other diversified industrial structure.

According to reports, the successful development of the ± 525kV flexible DC cable system is a wholly owned subsidiary of transit Technology Co., Ltd. Zhongtian Science and Technology Submarine Cable Co., Ltd. independently completed, and before that, Zhongtian cable also participated in the country three R & D work of DC submarine cables and DC cables. ± 525kV flexible DC cable is another self-transcendence after achieving "triple jump" of HVDC cables in China from ± 160kV to ± 200kV and ± 320kV, which shows once again the position of ZTT as the leader of China's HVDC cables .

The Innovation and Significance of ± 525kV Flexible DC Cable

According to Dr. Fu Mingli, a senior technical expert from China Southern Power Grid Research Institute and a national expert on "Thousand-Year Plan", at present, only the cable industry giants in a few countries such as Sweden, Italy, Norway and Japan have mastered ± 525kV DC cable system technology, However, after the successful product development, there is still no complete system applied to the actual project. However, with the development of offshore wind power in Europe, the United States and other power companies, as well as the planning of a super power grid with flexible DC transmission as the backbone, it provides a huge market prospect for HVDC cables. And Zhongtian Technology is also the only Chinese manufacturer jointly developed by the German Power Company to participate in the first ± 1000kV ± 525kV DC cable line project in its planning.

Dr. Fu Mingli believes that when China's power equipment, especially the development of EHV and UHV DC transmission equipment has become China's business card like China's high-speed rail technology, it is precisely we lack of a key technology, the connection technology of DC transmission technology, this time A major breakthrough I think it is of great significance to go abroad and participate in the competition in the international market for UHV and UHV DC transmission.

Zhongtian Science and Technology The development of ± 525kV flexible DC cable represents the highest level of domestic extruded insulated DC cable, there are four major innovations:

First, the successful development of independent development of the world's largest cross-section of 3000mm2 cross-sectional shape of the water-blocking conductor, which in turn opened up a new cable conductor technology, the highest voltage level of 525kV, is the highest in the country;

Second, the transmission capacity of up to 3000MW, than the current operation of ± 320kV DC cable capacity increased by 135%, is a world-class;

The third is to achieve power transmission + optical fiber communication + simultaneous temperature measurement of optical integration functions;

Fourthly, the technological breakthrough of the new type of metal shield structure for ultra-large size cables made the ± 525kV DC cable diameter developed by this study 10% smaller than that of the corrugated aluminum cable with the same voltage level and specifications.

Zhongtian Institute of Science and Technology and director of the submarine cable Institute, Professor Xie Shuhong, senior engineer said the company decision-making at the end of 2015 decided to start research and development, and Shanghai Jiao Tong University, Shanghai Electric Cable Research Institute, Institute of Global Energy Internet, Long cable electrician to establish production, learning, research, research and development mechanism, after a year and a half hard research, and finally in July 2017 passed the national wire and cable quality supervision and inspection center full-performance type test.

According to Xie Shuhong introduction, successful development of transit technology ± 525kV DC cable system is practicing the "two enhancements, two extensions" guidelines the best case. In the 2017 New Year's Speech, Xue Jiping, chairman of Zhongtian Science and Technology, proposed the guidelines for the operation of Zhongtian Science and Technology: "to enhance industrial productivity and increase added value of products", "to extend the industry to the high end and to extend its production capacity internationally." Ultra-high voltage cables are the commanding height of the cable industry. China has not yet made mass breakthroughs. It is difficult for China's ultra-high voltage cables to obtain international market permits. The transit technology by the German power company invited to participate in the German power ± 525kV DC cable joint R & D program, and successfully passed the type test, indicating that China's EHV cable technology officially among the world-class level.