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Highlights • AC loss of HTS coil under nonsinusoidal current. • Comparison with sinusoidal shows higher AC losses in the same peak current for nonsinusoidal current. • The investigation on loading factor and some discussions on quench. • Proper to use for superconducting machine design. Abstract Nowadays in the competitive generation and consumption electrical network, the efficiency is the key elements which should be carefully considered before purchasing electrical machines. It is not only important for achieving a better performance but also to keep the total ownership cost of the machine as low as possible. For this purpose, many research efforts have been done to involve superconducting material in electrical machine fabrication process. Recently, with continuous fast-development in production technology of second generation high temperature superconducting tapes, it is likely to achieve a very high efficiency with superconducting electrical machines. In order to investigate the efficiency, one needs to measure the losses of the superconducting wires under different operating conditions. It is quite common for an electrical machine to work under distorted supply current because they normally are driven with non-sinusoidal current of speed drives or supplying non-linear loads. In this paper, power loss of a double pancake high temperature superconducting coil which is supplied by harmonic-wave current has been experimentally measured and then, the results discussed which have shown, the power losses of distorted currents are wave-shape dependent and this loss decreases the loading ratio i.e. the ratio of operation current respect to critical current, significantly. [ABSTRACT FROM AUTHOR]

• Nonsinusoidal AC loss of superconducting tape/coil is investigated using finite element method. • Results are essential for all large scale applications of superconductivity. • Findings are useful for design of HTS transformers, and HTS power cables. • Harmonics increase the AC loss drastically and impose huge heat load to cryocooler. There are two main obstacles in front of the development of high temperature superconducting (HTS) technology for electric power network applications; tape price and cooling cost. In order to reduce cooling cost, it is vital to evaluate AC transport current loss of the tapes precisely and then reduce it by some design innovative approaches. In addition, AC transport current loss in HTS material is a critical design variable for large-scale power network applications such as HTS transformers, superconducting fault current limiters, and power cables, since they are continuously carrying the network/load current during their operating life. In existing power networks, harmonic production sources are commonly used and thus, currents are distorted. Therefore, the effect of nonsinusoidal current on the critical apparatus in the network such as transformer must be studied. In this paper, AC transport current loss of a single-turn 2G YBCO HTS coil was modeled and numerically calculated under nonsinusoidal transport current using finite element method. Furthermore, influence of dependency of critical current density to magnetic field on the AC transport current loss of HTS coil when carries distorted currents was considered. It was observed that nonsinusoidal current causes excessive losses in HTS coil. On the other hand, a case study on an HTS transformer supplying non-linear load was considered to study the loss increment as well as heat load change. It was observed that current harmonics increases the AC loss, and heat load of transformer and decreases the efficiency, consequently. [ABSTRACT FROM AUTHOR]