Real-time implementation of ring based saturated core fault current limiter to improve fault ride through capability of DFIG system

Enhancement of fault ride-through (FRT) capability in doubly-fed induction generator (DFIG) system is presented in this paper. The saturated core fault current limiter (SCFCL) works on the behaviour of magnetic field induction theory. It is composed of the ferromagnetic core with three limb construction, where both side limbs are surrounded with AC coil and middle limb with DC coil. For the application of restrictive fault, the ideal SCFCL can work for only low-power rating machines. But for the machine higher power rating, the ideal SCFCL has a drawback of developing heat across the limbs, which can damage the insulation of the coils. To overcome this glitch, the embedding of the copper ring across center limb and using forced-air cooling in SCFCL is used. This ring-based SCFCL (RSCFCL) is placed across the stator of DFIG system, which helps in minimizing fault current during any grid disturbances. Having low impedance during normal condition, it can be located permanently in the system without disturbing its stability. The feasibility of ideal SCFCL and RSCFCL is validated by studying the characteristics using thermal radiation under normal and fault conditions. The use of infrared imaging helps to monitor the thermographic patterns of the core on several conditions. The performance of RSCFCL is analyzed with the help of experimental setup and real-time simulator OPAL-RT 4510. Also, to check its effectiveness, it is used for FRT capability in the DFIG system application.