Abstract
Generators with high-temperature superconducting armatures have an advantage in the fact that they can carry high currents. However, the AC loss of high-temperature superconducting (HTS) armatures is difficult to calculate precisely because HTS coils exist in a complex and time-varying electromagnetic environment. In addition, when the HTS coil is carrying a short circuit fault overcurrent, an electromagnetic–thermal simulation study of this process is required to ensure that the HTS coil is not damaged. In this paper, first, a fully coupled T-A formulation model is used to calculate the AC loss of HTS armatures. Then, the current and temperature distributions are simulated, considering the intrinsic characteristic of superconducting coated conductors, when the generator suffers the worst short circuit fault accidently. It is found that the turn with the lowest critical current quenches after 0.01 s, but the temperature rise cannot damage the coil if the circuit breaker can clear the fault quickly. The effects of the copper stabilizer thickness on the thermal stability of the HTS coil during the worst short circuit fault are also investigated. A thicker copper stabilizer improves the thermal stability of the HTS coil in the event of a short circuit fault, but the use of a simulation model is needed to make trade-offs between the engineering current density and the thermal stability of the HTS tapes. The work in this paper is necessary and can provide an important reference for manufacturing superconducting generators.
Highlights
Second-generation (2G) high-temperature superconducting (HTS) generators are promising because they can achieve a higher power density compared to conventional generators [1]
The rotating machine is first simulated by the A-formulation, and the HTS coil is simulated by the H-formulation [10], with the boundary condition calculated from the A-formulation model
The main results in this paper are summarized as follows: First, by coupling the field part model with the circuit part model, the AC loss of HTS coils during rated operation is calculated
Summary
Second-generation (2G) high-temperature superconducting (HTS) generators are promising because they can achieve a higher power density compared to conventional generators [1]. The T-A formulation model can directly achieve the fully coupled simulation of the HTS coils under the generator’s electromagnetic environment because rotating generators are usually simulated by the A-formulation [13]. To understand whether the short circuit fault will cause permanent damage to HTS coils, conducting an electromagnetic thermal coupling simulation is of great importance. Some numerical simulations of the short circuit faults of HTS generators have been done [15,16,17,18,19] None of these simulations achieves fully coupled simulations, considering the dependence of the critical current density on the temperature and the magnetic field.
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