The second-generation (2 G) high temperature superconducting (HTS) conductor is widely used in high-field magnets and power transmission cables and its AC loss is one of the main obstacles. This paper mainly analyzed AC losses of twisted quasi-isotropic conductor stacked by 2 G HTS tapes and copper tapes by simulation and experimental methods at 77 K. A twisting apparatus was designed and manufactured for fixing and twisting the quasi-isotropic conductor accurately and the transport AC losses of the conductor with different twisted angle were measured by four-probe method under different frequencies. Meanwhile, a 3D simulation based on the T-A formulation was adopted to handle simulation challenges of HTS tapes with high aspect ratio and overall understand AC losses on the twisted quasi-isotropic conductor. Simulation results are in good agreement with the measured ones and the current distribution in the HTS tapes was investigated in detail. The results are helpful for fully understanding transport AC losses characteristics of twisted quasi-isotropic conductor.

第二代（2 G）高温超导（HTS）导体广泛用于高磁场磁体和输电电缆，其交流损耗是主要障碍之一。本文主要通过仿真和实验方法，分析了2G HTS带和铜带叠置的准各向同性双绞导体在77 K时的交流损耗。设计并制造了一种扭绞装置，用于精确固定和扭曲准各向同性导体并进行运输。采用四探针法在不同频率下测量了不同扭角导体的交流损耗。同时，基于TA的3D模拟公式被采用来处理高纵横比的HTS胶带的模拟挑战，并总体上理解了扭曲的准各向同性导体上的AC损耗。仿真结果与实测值吻合良好，并详细研究了高温超导带中的电流分布。研究结果有助于充分理解准各向同性导体的交流输电损耗特性。