12 - High-temperature superconducting (HTS) transformers for power grid applications

Abstract

This chapter discusses high-temperature superconducting (HTS) transformers with an emphasis on the technical and cost barriers they must surmount to supplant conventional transformers in the power grid. Requirements for conventional transformers with respect to short circuit current limitation, overload capacity, electrical insulation, voltage regulation, efficiency, and mitigation of fire hazards are reviewed since these constrain the operation of HTS transformers. Salient features of HTS conductors and cryogenic operations and the status and achievements of HTS transformer development worldwide are reviewed. AC loss in HTS transformer windings is considered, especially the use of multiple conductors to attain high currents using transposition at the coil level or as continuously transposed cable. Cryostat and cryocooler technology and progress on achieving transformer performance goals, especially relating to fault current performance and conductor loss, are reviewed. The economic viability of HTS transformers is reviewed from the viewpoint of total cost of ownership.