Calculation of Alternating Current Distribution on the Current Lead for HTS Power Cable

Abstract

High temperature superconductor (HTS) power cable can obtain substantially lower transmission losses than conventional cables. Termination of HTS cable is a connecting part between copper electrical cable at room temperature and HTS cable at liquid nitrogen temperature. Alternating current (AC) has been considered as an important parameter for the design of current lead for the HTS cable termination. When AC were flowing on the current lead currents were mainly distributed on the edge of the current lead due to skin effect and resulted in the nonuniformity of the current density across the cross-section of the current lead. As area increased, the influence of skin effect became serious and therefore Joule heating, i.e., AC loss generated on the AC current lead increased. In order to reduce the nonuniformity of the current distribution, an AC current lead has divided into several current leads that have smaller cross-sections than the original current lead. In this case, however, the array of current leads was important because the inductance from each current lead was different depending on the position. Heat load calculations on the copper current lead have been performed by analytical and numerical method. Larger heat loads were generated on the AC current lead than on the direct current (DC) lead because of the skin effect. In addition, the effect of inductance on the current distribution was investigated. As the gap distance between current leads decreased the effect of mutual inductance was found to be important. For this case has increased current amount generated on the current lead as well as AC loss. Also, the current direction in each small area current lead varied depending on the gap distance.