Excitation Current and Harmonic Analyses of a Three-Phase Five-Limb Transformer Under GIC According to Different Core Cross-Section Ratios

This paper examines the effect of end-limb and yokes cross-section ratios on magnetizing current and its harmonics for a three-phase five-limb autotransformer in the presence of Geomagnetically Induced Current (GIC). The transformer core saturates due to half-cycle saturation, the exciting current reaches high peaks and produces odd and even harmonics under high-level dc bias. ANSYS Maxwell software used the field-circuit coupled finite element method to model three-phase five-limb autotransformers with different end-limb and yokes cross-sections in 2D for simulations in the transient solver. Finally, the simulation results shared the effects of the end-limb and yoke cross-section ratios through graphics.