Short-Circuit Fault Simulations in an HTS Wind Generator With Different Mechanical Conditions

The high-temperature superconducting (HTS) generators are proposed as a promising method to reduce the weight and size of the large-scale off-shore wind generators. However, the lower reactance of an HTS generator makes short-circuit faults heavier. The short-circuit fault problems of an HTS generator are complicated. A simulation is an effective way to study the generator's performances under fault conditions. However, different mechanical conditions affect the simulation results. In this paper, the performance of a 2.5 MW HTS wind generator under short-circuit fault conditions is studied by coupling the finite element method model and the equivalent circuit model. The mechanical conditions are set by three different methods that are the constant rotation speed method, the constant torque method, and the constant power method. The results in these three methods show similar peak values in transient processes, but different developing processes and different final states. The peak values of the electromagnetic torque, armature current, and field winding current appearing in the transient process should be considered when designing the HTS wind generators. This study provides a criterion to set mechanical conditions in the short-circuit fault model of an HTS wind generator, and also provides data for future work about the quench protection of the HTS field windings.