Ahmad Ghafari - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Mohsen Saniei - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Morteza Razaz - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Alireza Saffarian - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

Connection of new distributed generation (DG) units in a grid connected micro-grid can be a major reasonfor increasing the short-circuit level in these networks. It can also disrupt the protective coordination of the existingover-current relays (OCRs) in both main grid and micro-grid. Application of the fault current limiters (FCLs) betweenthe main grid and micro-grid is one of the ways to overcome the above-mentioned problems. However, it is proven thatwhen a short circuit fault occurs in the micro-grid, the limiting impedance of the conventional FCL has an adverseeffect on the coordination between the main grid and micro-grid OCRs. The active superconducting current controller(ASCC) is a new device which can limit the fault current as a series voltage compensator. In this paper, three operatingmodes of ASCC including normal mode, upstream fault mode and downstream fault mode are proposed to achieve anadaptive FCL that solves the mentioned problems in the grid connected micro-grid. The simulation results illustrate theeffectiveness of the proposed method in comparison with the previous methods that use the conventional FCLs.

Fault current limiter; Active superconducting current controller; Grid connected micro-grid; Protectivecoordination.