A Novel Three-Phase Saturable-Core Fault Current Limiter Structure

Fault current limiters (FCLs) can play an important role in providing protection of power systems against high fault current levels. This paper proposes a new three-phase structure of saturable-core FCL based on the common core for all three phases. Due to the existence of flux linkage between all three phases, the resulting electromagnetic fluxes negate each other, and therefore the inductance in the normal condition is significantly reduced. In this structure, the dc winding compensates just the imbalance of phase currents in the system. Therefore, the number of dc winding turns decreases, and consequently the induced voltage across this winding is reduced. This structure leads to a significant reduction in the volume of the core. The FCL design algorithm with the new structure is presented. In order to validate the effectiveness of the proposed FCL, simulation is carried out based on the finite-element method and a prototype is made and tested. The results prove the efficiency of the proposed method.