Guidelines for 2D/3D FE transient modeling of inductive saturable-core fault current limiters

Abstract

Fault Current Limiters (FCLs) are expected to play an important role in protection of future power systems. FCLs can be classified in three groups: passive, solid-state and hybrid FCLs. Passive FCLs have merit to inherently react on a fault, requiring no fault detection and triggering circuit. Inductive FCLs based on core saturation belong to this group. Analytical models, used for design of inductive FCLs, are not accurate enough; BH curve cannot be expressed as an explicit function. Numerical models offer better approximations, but they often do not include effects such as leakage and fringing fluxes, which can have considerable influence on the result. Verification of such models is of utmost importance. Finite element modeling (FEM) tools offer possibility to model any inductive FCL topology, while all the effects, e.g. non-linear BH curve, fringing effects etc., are taken into account. However, the modeling of these devices in FEM softwares is difficult. This paper introduces the guidelines for development of 2D/3D transient FE models of inductive FCLs in Ansys. The guidelines are developed with respect to the single-core inductive FCL topology. The model can be applied to any inductive FCL and presents a valuable tool for design, verification and optimization of these devices. Signals' waveforms, obtained through the transient analysis, provide precise depiction of FCL operation during both normal and fault regimes. The model is validate by means of lab experiment. Simulation and experimental results show very good matching. In addition, modeling results are used to prove that single-core FCL topology operates properly during both nominal and fault regimes.