Recent Progress and Design of Three-Phase Coaxial HTS Power Cable in Korea
High-temperature superconducting (HTS) power cables were developed recently and have several advantages over conventional cables. For high current capacity, two or more layers are required in one phase of the HTS cable. Differences in the radii between each phase and layer cause inherent imbalance and non-uniform current distribution of three-phase currents. These outcomes must be minimized by properly designing the pitches of multi-layer three-phase coaxial HTS cables. In this paper, the authors design the conduction layers of a multi-layer three-phase coaxial HTS cable and analyze the characteristics of the designed cable based on the proposed PSCAD/EMTDC component and simulation method. A 23 kV/60 MVA multi-layer three-phase coaxial HTS power cable is considered. The conceptual design of a multi-layer three-phase coaxial HTS cable includes the radii of each layer, the number of layers in each phase, and the pitch design of each layer of the cable. Using an impedance matching program, current imbalance can be minimized and current distribution can be made uniform in all layers of the phase by adjusting the pitch length and winding direction. The characteristics of HTS cables using the proposed PSCAD/EMTDC component are analyzed. In this component, the dynamic resistance of current- and temperature-dependent HTS cables is added to the HTS model. AC losses are calculated using the some equation. Induced current loss is calculated based on the material properties of the shield layer. A transient simulation is performed for a three-phase fault of the three-phase coaxial HTS cable using a PSCAD/EMTDC-based simulation method.