Design and Evaluation of 66 kV Class HTS Power Cable Using REBCO Wires

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High temperature superconducting (HTS) cables achieve large power capacity and low-loss power transmission in a compact package. In a new Japanese national project, Sumitomo Electric Industries, Ltd. is working to develop a 66 kV–5 kArms HTS cable with REBCO wires. One of the important technical targets is to reduce AC loss to less than 2 W/m/ph at 5 kArms. To investigate the effect of wire width on the AC losses in multi-layer cable conductors, 30-mm-wide REBCO tapes were divided into 4-mm-wide or 2-mm-wide strips, and two 4-layer cable conductors were manufactured with these strips. The measured AC loss characteristics of the two cable conductors were comparable. The measured AC loss in the cable conductor with 4-mm-wide wire was in good agreement with numerical calculations. However, the AC loss in the cable conductor with 2-mm-wide wires was larger than the numerical prediction. The difference may be due to the wires' non-uniform <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{c}$</tex> </formula> distribution in the width direction, because the AC losses in cable conductors with narrow wires are strongly influenced by the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$J_{c}$</tex></formula> profiles of the wires. AC loss simulations assuming that the wire's <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I_{c}$</tex> </formula> will be higher show that a 14000 A- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$I_{c}$</tex></formula> class cable with 4-mm-wide wires is expected to achieve the AC loss target. For cables with 2-mm-wide wires, the improvement of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{c}$</tex> </formula> distribution in the width direction will reduce the AC loss level, and the goal will be achieved with lower <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I_{c}$</tex></formula> wires.