Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

• A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid.
• The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability.
• The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes.
• The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability.

Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.