A 3D Finite Element Method Approach for Analyzing Different Short Circuit Types in a Saturated Iron Core Fault Current Limiter

In several cases, substations have become incapable of supporting faults due to short circuit levels increasing. Fault current limiters (FCLs) are a potential solution for this problem. Among several FCL topologies presented in the literature, the saturated Iron-Core Superconducting Fault Current Limiter (SIC-SFCL) has shown promising results in real tests in substations. In this context, this paper presents the impacts of the different kinds of short circuits in the SIC-SFCL device. To reproduce various types of faults, the SIC-SFCL is modeled in a 3D framework considering both ferromagnetic and superconducting non-linearities. Moreover, the proposed 3D FEM model can couple the SIC-SFCL to the electric power system, also representing the electrical grid and the protection systems. For this investigation, the DC-biased superconducting coil's normalized current density and the iron cores' magnetic flux density are examined in light of the different short circuits. The simulations are compared with measurements in a bench prototype, showing a maximum error of 16.5~%. Furthermore, different short circuit types were investigated and compared, which is possible only using a 3D model. The highest limitation occurred in the phase-to-phase short circuit case. In the DC circuit of the SIC-SFCL, the highest transient period has happened in the single-phase short circuit. At last, the phase-to-phase fault presented the highest DC current during the transient.