In this paper, the power burden of High-TC superconducting (HTSC) module comprising the flux-lock type superconducting fault current limiter (SFCL) with two triggering currents during the fault period was analyzed. The short-circuit tests for the simulated power system with the SFCL in the different fault positions, which were expected to affect the amplitude of the fault current, were carried out. Through the comparative analysis on the power burden of the HTSC modules, the proposed flux-lock type SFCL was confirmed to be effective to divide into two power burdens according to the amplitude of the fault currents.

The flux-lock type superconducting fault current limiter (SFCL) connects the two parallel windings in parallel with a ferromagnetic core. We suggest that the double quench flux-lock type SFCL should add a third winding. We analyzed characteristics of the fault current and the peak current using the quench of the high-Tc superconducting element. The proposed SFCL’s inductances of a primary winding and the third winding were fixed and the amplitude of inductance of the secondary winding was changed. We found that the fault current can be more effectively controlled through the analysis of the equivalent circuit and the short-circuit tests.

The superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes and plays a role in compensating the voltage sag of the sound feeder adjacent to the fault feeder as well as the fault current limiting operation of the fault feeder. Especially, the flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, has different voltage sag compensating and current limiting characteristics due to the winding direction and the inductance ratio of two coils. The current limiting and the voltage sag compensating characteristics of a SFCL using a transformer winding were analyzed. Through the analysis on the short-circuit tests results considering the winding direction of two coils, the SFCL designed with the additive polarity winding has shown the higher limited fault current than the SFCL designed with the subtractive polarity winding. It could be confirmed that the higher fault current limitation of the SFCL could be contributed to the higher load voltage sag compensation.

In this paper, we investigated the fault current limiting and the load voltage sag suppressing characteristics of the flux-lock type SFCL, designed with the additive polarity winding, according to the variations of turn number`s ratio and the comparative analysis between the resistive type and the flux-lock type SFCLs were performed as well. From the analysis for the short-circuit tests, the flux-lock type SFCL designed with the larger turn number`s ratio was shown to perform more effective fault current limiting and load voltage sag suppressing operations compared to the flux-lock type SFCL designed with the lower turn number`s ratio through the fast quench occurrence of the high-TC superconducting (HTSC) element comprising the flux-lock type SFCL. In addition, the recovery time of the flux-lock type SFCL after the fault removed could be confirmed to be shorter in case of the flux-lock type SFCL designed with the lower turn number ratio.

The fault current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL) using a transformer winding were investigated. The suggested flux-lock type SFCL consists of two parallel connected coils on an iron core and the transformer winding connected in series with one of two coils. In this SFCL, the high-TC superconducting (HTSC) element was connected with the secondary side of the transformer. The short-circuit experimental devices to analyze the fault current limiting characteristics of the flux-lock type SFCL using the transformer winding were constructed. Through the short-circuit tests, the flux-lock type SFCL using transformer winding was shown to perform more effective fault current limiting operation compared to the previous flux-lock type SFCL without the transformer winding from the viewpoint of the quench occurrence and the recovery time of the HTSC element.

When the current of the superconducting element exceeds its critical current by the fault occurrence, the quench of the high-TC superconducting fault current limiter (HTSC) comprising the flux-lock type superconducting fault current limiter (SFCL) occurs. Simultaneously, the magnetic flux in the iron core induces the voltage in each coil, which contributes to limit the fault current. In this paper, the fault current limiting characteristics of the flux-lock type SFCL as well as the load voltage sag suppressing characteristics according to the flux-lock type SFCL`s winding direction were investigated. To confirm the fault current limiting and the voltage sag suppressing characteristics of the this SFCL, the short-circuit tests for the simulated power system with the flux-lock type SFCL were carried out. The flux-lock type SFCL designed with the additive polarity winding was shown to perform more effective fault current limiting and load voltage sag suppressing operations through the fast quench occurrence right after the fault occurs and the fast recovery operation after the fault removes than the flux-lock type SFCL designed with the subtractive polarity winding.