Design, Manufacture, and Test of a 30 m 10 kV/2.5 kA Concentric HTS Cable Prototype for Urban Grid

Abstract

High temperature superconducting (HTS) cable, with significant low dissipation and massive current carrying capability, is a promising solution for the shortage of transmission capacity in mega-cities. China Southern Grid launched a HTS cable project in 2017 to develop a medium voltage concentric HTS cable system for installation in the distribution grid at urban area in Shenzhen City. It is the first time that concentric HTS cable system is developed and will be the first HTS cable installed in urban grid in China. The cable core mainly consists of three concentric phases winded by YBCO tapes and cold dielectric insulations in between phase-to-phase, phase-to-former, and phase-to-screen. The cable has a rated voltage of 10 kV and a rated current of 2.5 kArms. The critical current (I c ) is at least 6 kA per phase. The outline diameter of the cable core is 76 mm and the cryogenic pipe is 175 mm. As a middle step, we designed and manufactured a 30 m long prototype cable system and it was tested generally according to IEC 63075. For improvement of the manufacture processes, several short cable core samples were made, tested, and dismantled. The ultimate goal of the 30 m prototype is to verify the design and accumulate experience for the installation of the 400 m fully functional cable system in the grid. The test results of the 30 m cable prototype are presented and discussed. The 400 m class HTS concentric cable demonstration project has already started and it is expected to energize in grid in late September, 2021.

Development and demonstration of concentric-type HTS power cable for distribution grid in Shenzhen urban

“…To fully validate the system design, a 30 m prototype system (Figure 6) was developed. We conducted type test on the prototype according to IEC 63075 and Chinese National Standards, the results had been reported in our earlier paper (Wang et al, 2021). In addition, we have conducted a lot of research experiments, such as AC loss, shielding layer current under unbalance, overcurrent shock, and so on.…”

Transient research on distribution networks incorporating superconducting cables utilizing field–circuit coupling method

“…Based on the geometric parameters listed in table 1, the selfinductance and mutual inductance of each conductor layer can be calculated by the above equations. According to the experimental results of the sample cable [8], the phase inductance of the tri-axial CORC cable is about 0.056 µΩ m −1 . Thus, the relative error of the calculated results is less than 5 nΩ m −1 , which verifies the reliability of the inductance calculation.…”

“…To maintain the superconducting state of the HTS cable during operation, the cable is immersed in subcooled liquid nitrogen along its length, at a temperature of approximately 70-74 K [8,19]. It should be noted that the vaporization of liquid nitrogen can result in the frequent activation of the pressure relief valve, and the subsequent generation of bubbles can lead to partial discharge [53].…”

“…Therefore, not limited by underground tunnels or pipes, superconducting cables can replace conventional cables in existing cable trenches, which not only saves space and reduces investment, but also meets the high load requirements of metropolises [5]. Based on the above analysis, dozens of superconducting cables have been constructed in the past three decades [6], two of which with a capacity larger than 20 MW have been integrated into the power grids of Shanghai and Shenzhen in the last two years [7,8]. Given the important load of these two global cities, it is crucial to ensure a reliable power supply by addressing the fault and protection mechanisms of the distribution network.…”

J model for studying AC magnetization loss in 3D cable structures

“…In recent years, many projects around the world involving high-temperature superconductivity (HTS) have been successfully completed and tested, including high-field magnets [1], superconducting current limiters [2], and superconducting cables [3]. In these applications, flux penetration will occur in the superconductors.…”