Model and Simulation of a HTS Generator under transient response

Use of HTS field windings in electrical rotating machines can increase the torque density by a factor of 2-3 compared to conventional designs. This is highly attractive for large scale applications, such as ship propulsion and wind turbines. However, design considerations have to take into account hysteresis losses in the HTS materials during transients.

Modeling and simulation of these transients is a very challenging task. It requires considering a system that spans spatially 6 orders of magnitude: from the μm thick superconducting layers in the windings, to a few meters in diameter and length of the MW class machines. In this work, we present a bottom-up model of a 10MW HTS slotless generator for a direct drive wind turbine application.

The model is used to simulate the transient response of the generator where focus is placed on the losses associated with ramp-up of HTS coils with different rise times and transient responses. Hence, transient hysteresis losses in the superconducting coils were computed. This allowed addressing several important design and performance issues such as defining the safety margin of the load line to the critical current of the superconducting coils, electric load change rate, cryostat design and identification of quench-prone regions.