Optimal allocation of flux-coupling-type SFCLs for a micro-grid with wind-PV hybrid generation and battery energy storage

Regarding the access of a micro-grid with multiple distributed generation (DG) units into the power distribution network, superconducting fault current limiters (SFCLs) may be used to improve the micro-grid's robustness against short-circuit faults. In this paper, the flux-coupling-type SFCL is selected to play the role, and the optimal allocation of the SFCLs for protection of a micro-grid with wind-PV hybrid generation and battery energy storage is performed. The SFCL's structural principle is conducted first. Further, those candidate allocation scenarios of the SFCLs used in the micro-grid are enumerated, and each of them includes installation number, mounting location and impedance parameter. Besides, a matching optimal objective function is proposed, and herein the each SFCL's current-limiting performance and the micro-grid's frequency stability are considered as two key optimization criterions. Time-domain simulation is done, and the results imply that the SFCL should be located on the direct path of current flowing from the DG and the main network. Through the optimal utilization of the fluxcoupling-type SFCLs, it can be obtained that reduce of the fault current, inhibition of the frequency fluctuation and acceleration of the system restoration. Thus, the micro-grid system's transient stability is enhanced well.