Conceptual Design and Performance Evaluation of a 35-kV/500-A Flux-Coupling-Type SFCL for Protection of a DFIG-Based Wind Farm

In this paper, a flux-coupling-type superconducting fault current limiter (SFCL) is suggested to protect a 15-MW class doubly fed induction generator (DFIG)-based wind farm. Detailed conceptual design and performance evaluation of the SFCL are conducted. From the technical requirements and operational parameters of the DFIG wind farm, a 35-kV/500-A flux-coupling-type SFCL is designed, taking into consideration: 1) the winding type, core selection, and inductance values of the coupling transformer (CT); and 2) the structural style, tape length, and quenching resistance of the superconducting coil (SC). By use of different simulation tools, the electrical and electromagnetic characteristics of the SFCL are evaluated. The results show that the maximum magnetic field of the CT is 2.4 T, and the ac loss of the SC is 0.51 W. Not only the electromagnetic properties and loss of the SFCL are acceptable, but also using the SFCL in the wind farm enables to suppress the fault current, compensate the voltage sag, and mitigate the wind power fluctuation. Thus, the robustness of the DFIG-based wind farm against the fault is enhanced, and the effectiveness of the proposed SFCL design is verified.