Stability Analysis of the Cable Core of a 10 kA HTS DC Power Cable Used in the Electrolytic Aluminum Industry

High temperature superconducting (HTS) dc power cable shows a wide application prospect in the field of power transmission for its nearly lossless and rather high capacity. IEE has installed a 360-meter long high temperature superconducting (HTS) dc power cable at the self-supply power plant of Zhongfu Industrial Company Ltd. in Gongyi, Henan and the system has operated for two years. The cable connects a 19.5 MVA/1.5 kA silicon-controlled rectifier, which connects with a 110 kV/1 kV transformer, to the bus bar of an electrolytic aluminum cell. It is designed to carry 10-kA current and the voltage is 1300 V. The HTS dc power cable core consists of five conductor layers wound with the spliced Bi-2223 wires with the length of 40 km. The cable core has five layers and 23 HTS wires in each layer with the outer diameter of 45 mm. The HTS dc power cable is fabricated with the spliced superconducting wires which will have effect on the overall superconductivity. Also, since dc output of the rectifier contains a proportion of the ac harmonic ripple, the large dc and small ac will generate the loss in the cable core. In the operation of the 10 kA HTS dc power cable, anode effect will occur in electrolytic aluminum tank, which will lead to a large fault current in the cable and even lead to the power off protection. In this paper, stability of the spliced Bi-2223 wire, stability of the cable core under the cold shrinkage force, loss under the large dc and small ac ripple are analyzed by the theoretical and experimental methods. The test results of ac ripple loss, anode effect, and stable operation are also presented.