Zhoushan, Zhejiang: 640kV UHVDC Cable Test Platform Completed and Put into Operation

Recently, following the successful commissioning of China’s first long-term energized comprehensive performance test platform for high-voltage direct current (HVDC) cables in 2024, the “Guojiao-1” technological innovation team of State Grid Zhoushan Power Supply Company has achieved another major breakthrough the independently developed 640kV ultra-high voltage direct current (UHVDC) cable comprehensive performance test platform has been completed and put into operation. This platform has raised the test voltage level to an internationally leading standard, marking that China has entered a new phase in the field of UHVDC cable test technology and equipment, and injecting stronger impetus into supporting the development of offshore clean energy and the interconnection of cross-sea power grids.

As China accelerates the advancement of major projects such as deep-sea offshore wind power and cross-sea power grid interconnection, the demand for DC submarine cable transmission capacity, voltage level, and reliability continues to rise. In 2024, the “Guojiao-1” team built China’s first set of HVDC cable test platforms, overcoming the industry-wide problem of abnormal temperature rise caused by armoring eddy current loss in traditional AC current boosting methods, and achieving a core technological breakthrough in the simultaneous application of DC current and voltage. This year, based on the current need for large-scale integration of offshore energy, the team further broke through the technological bottleneck of 640kV voltage level testing and built China’s current highest-voltage-level comprehensive performance test platform for UHVDC cables.

The platform innovatively adopts all-DC multi-physics field coupling technology, which can accurately simulate the long-term operating conditions of cables under 640kV voltage, 10,000-ampere-level current, and complex marine environments. It completely eliminates deviations in the gradient distribution of insulation temperature, and the consistency between test data and actual operating conditions has reached an internationally leading level. At the same time, the platform is equipped with a new generation of optical fiber intelligent monitoring system, which realizes millisecond-level dynamic capture and full-dimensional analysis of cable conductor temperature rise, providing high-precision test support for the optimization of UHVDC cable design and the performance verification of domestic insulating materials.

In recent years, the scale of China’s DC cable projects has continued to expand, but the technology for evaluating the long-term energized performance of high-voltage-level cables has long been constrained by insufficient testing capabilities. Traditional methods cannot reproduce the real distribution of electromagnetic fields and temperature fields, making it difficult to identify cable system design defects in advance. The newly commissioned 640kV test platform, through full-operating-condition simulation technology, can continuously conduct energized assessment tests on cable systems for hundreds of hours, providing early warnings of potential faults and effectively improving the full life cycle of cable projects. “This is equivalent to building a ‘comprehensive hospital’ for UHVDC cables,” said Gao Zhen, the technical director. “The platform can not only provide grid-connection ‘physical examinations’ for cables used in major projects but also accelerate the large-scale application of domestic high-voltage cable insulating materials, helping to break the monopoly of foreign material technologies.”

As the “national team” in China’s marine power transmission technology field, the “Guojiao-1” team has continuously led industry technological innovation: it has built the world’s first full-scenario test system for marine cables covering underwater detection, AC/DC testing, and environmental simulation; it has led the compilation of a number of national and international standards such as the Design Code for Submarine Power Cable Transmission Projects, promoting China’s marine cable engineering standardization to rank among the world’s forefront; it has undertaken the national key research and development program project “Key Technologies for DC Cable Systems,” achieving full-chain breakthroughs from material research and development to engineering application.

The commissioning of the 640kV test platform this time marks that China has formed independent testing capabilities for DC cables covering voltage levels of 640kV and below, laying a foundation for the subsequent research and development of cables with higher voltage levels. In the future, the team will continue to tackle key technologies for UHVDC cable intelligence and greenization in response to strategic needs such as deep-sea offshore wind power transmission and cross-sea energy interconnection networks, contributing to the achievement of the “dual carbon” goals and the construction of a maritime power. (By Zhang Cifeng/Gao Zhen/Zhang Yinxian)