A Study on AC Losses of HTS Pentagonal Conductors Consisting of 2G Wires Carrying DC Offset Transport Current

In a high-voltage dc (HVDC) transmission system, a high-temperature superconducting (HTS) dc cable is a feasible candidate due to its high power density. However, the dc in the grid includes ac ripple generated from switching devices and the environment, which can cause ac losses. In this paper, two pentagonal conductors consisting of second-generation (2G) wires are prepared, and their ac losses are investigated under the application of current with ac and dc components. Moreover, a numerical analysis is performed for both conductors to compare the measured losses. The results show that the measured ac losses correspond well with the numerical ones calculated by our models. The dc offset current does not affect the ac losses when the total current is smaller than the critical current, and the ac losses depend on the amplitude of the ac component. All measured losses are verified by evaluating the dependence on the arrangement of the voltage leads, the contact position, and the frequency.