ASOG-SP-Based Design Optimization of a Permanent-Magnet-Biased Fault Current Limiter Using Nonlinear FEM and Experimental Validation

Abstract

 This paper presents the design and optimization of a single-phase permanent-magnet-biased fault current limiter (PMFCL) using nonlinear finite-element modelling (FEM), an Adaptive Single-Objective Gradient Single-Point (ASOG-SP) optimization method, and experimental validation. The proposed PMFCL employs permanent-magnet biasing to establish a controlled magnetic operating point during normal operation and increase the effective impedance during fault conditions. The initial design has a core area of 180 mm², magnetic-path length of 68 mm, air gap of 1.5 mm, permanent-magnet thickness of 2 mm, and 200 winding turns. Following ASOG-SP optimization, these parameters are adjusted to 195 mm², 65 mm, 1.2 mm, 3 mm, and 220 turns, respectively. Under the specified simulation conditions, the peak fault current decreases from 1.72 A to 1.27 A, corresponding to a 26.2% reduction. Experimental testing further demonstrates a reduction in peak fault current from 5.5 A without the PMFCL to 3.1 A with the optimized device, corresponding to a 43.6% reduction. The optimized design is also evaluated in terms of magnetic flux distribution, voltage characteristics, and harmonic behavior. The results demonstrate that coordinated optimization of magnetic geometry and winding turns enhances fault-current-limiting performance while maintaining suitable normal-state operation. The proposed nonlinear FEM-based framework provides a practical approach for PMFCL design, optimization, and experimental assessment.