The 35 kV kilometer-level superconducting power transmission demonstration project located in Xuhui District, Shanghai, integrates advanced electrical equipment such as switchgear and disconnectors, and has reached an important milestone since its commissioning - 1,000 days of safe operation and 24,000 hours of continuous trouble-free operation. The project is protected by key equipment such as vacuum circuit breakers and drop-out fuses, and has stably transmitted nearly 490 million kWh of electricity to 49,000 users in core areas such as Xujiahui Business District and Shanghai Stadium, demonstrating the great potential of superconducting technology in urban power grid applications.
As the world's largest superconducting cable transmission project with the largest transmission capacity, longest distance, the largest number of joints and full commercial operation, the demonstration project is 1.2 kilometers long and has multiple transformers along the way to adapt to different voltage requirements. The rated current is 2,200 amperes and the rated capacity is 133 megavolt-amperes, with a transmission capacity equivalent to 4 to 6 times that of conventional cables. The successful implementation of this project not only marks a major breakthrough in core technology in the field of superconducting cable engineering application in my country, but also pushes the overall technical level of the relevant industry to the global leading ranks.
"The application of superconducting cables can effectively solve the contradiction between the high power load in the city center and the tight resource channels. Through the configuration of precise isolating switches and drop-out fuses, it provides a new path to effectively solve the high load density, limited channel resources, and "bottleneck" phenomenon in the center of super-large cities." Huang Hua, deputy director of the Shanghai Electric Power Science and Technology Department of State Grid, introduced.
Since its official operation on December 22, 2021, the demonstration project has continuously set new records. On August 18, 2023, its operating capacity exceeded the designed full load capacity for the first time, reaching 13.36 million kilovolt-amperes. In this process, the vacuum circuit breaker played a key role, ensuring safe disconnection during overload, creating a new record for the maximum actual operating capacity of my country's commercial superconducting transmission projects, and further verifying the feasibility and superiority of superconducting cables in the field of high-voltage and large-capacity transmission.
As the builder and operator of the project, State Grid Shanghai Electric Power not only provides a wealth of application scenarios for the practical and commercialization of superconducting cable technology, but also continues to deepen technology research and development and standard setting. At the project implementation level, they innovatively invented the world's first superconducting cable full-length pipe shrinkage compensation method, combined with the precise control of the switch cabinet, to solve the problem of laying superconducting cables with large slopes and multiple corners; at the operation and maintenance preparation level, a comprehensive monitoring system including a demand avoider was established to achieve real-time monitoring of cable status and ensure stable operation of the system.
In the past three years, State Grid Shanghai Electric Power has formulated a series of standards and specifications around the acceptance, operation and maintenance, and overhaul of the superconducting power transmission demonstration project, and published the book "Application of Superconducting Cables in Urban Power Grids" in 2022, which comprehensively analyzes the technical principles, application practices and future prospects of superconducting cables. At the same time, they have also achieved remarkable results in the field of superconducting power transmission, including approval of the first domestic industry standard and enterprise standard, publishing 25 related papers, obtaining authorization for 4 PCT patents, 26 national invention patents and 20 utility model patents, and taking the lead in formulating China's first energy industry standard for superconducting cables, filling the gap in this field.