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

• Published in: IEEE transactions on applied superconductivity 2022-04, Vol.32 (3), p.1-13
• Main Authors: dos Santos, Gabriel, Martins, Flavio Goulart R., Sass, Felipe, Sotelo, Guilherme Goncalves, Morandi, Antonio, Grilli, Francesco
• Format: Article
• Language: English
• Subjects: Circuits; Coated conductors; Coils; coupling method; Couplings; Current limiters; Electric power grids; Electric power systems; Ferromagnetism; Finite element analysis; Finite element method; Flux density; High-temperature superconductors; Integrated circuit modeling; Iron; Magnetic flux; Magnetism; Protection systems; Short circuits; Substations; Superconducting coils; superconducting fault current limiter (SFCL); Superconducting magnets; Superconductivity; T-A formulation; Three dimensional models; Three-dimensional displays; Topology
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2022.3142047

In several cases, substations have become incapable of supporting faults due to increase in short-circuit levels. 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 article presents the impacts of different kinds of short circuit on the SIC-SFCL device. To reproduce various types of fault, the SIC-SFCL is modeled in a 3-D framework considering both ferromagnetic and superconducting nonlinearities. Moreover, the proposed 3-D finite-element method 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-bias superconducting coil's normalized current density and the iron cores' magnetic flux density are examined in light of different kinds of short circuit. The simulations are compared with measurements in a bench prototype, showing a maximum error of 16.5%. Furthermore, different types of short circuit are investigated and compared, which is possible only using a 3-D model. The highest limitation occurs in the phase-to-phase short-circuit case. In the dc circuit of the SIC-SFCL, the highest transient period happens in the single-phase short circuit. Finally, the phase-to-phase fault presents the highest dc current during the transient.