Investigating the impact of magnetic air gap variations on short circuit characteristics of partially high temperature superconducting generator

Abstract

Partially high-temperature superconducting generators (PHTSGs) feature large magnetic air gaps imposed by using cryostats for HTS field windings. This increased air gap significantly affects end winding inductance and can lead to elevated fault torque levels. This study investigates the influence of magnetic air gap variation on generator design and end winding inductance and its implications for short-circuit faults in PHTSGs. Through a combination of numerical simulations and analytical analysis, the study explores how changes in the magnetic air gap affect end winding inductance and subsequently influence short-circuit fault behavior. The results reveal a direct correlation between magnetic air gap length, end winding inductance, and key short-circuit parameters such as stator current, field currents, and electromagnetic torque. Notably, an increase in the magnetic air gap is observed to elevate stator and field currents and electromagnetic torque during short-circuit events. These insights underscore the importance of considering magnetic air gap variation and its impact on end winding inductance and its relationship with short circuit characteristics in the design and operation of PHTSGs, providing valuable insights for enhancing the resilience and performance of high-temperature superconductor-based generator systems.