FEM analysis of DC saturation to assess transformer susceptibility to geomagnetically induced currents

Results are presented of a systematic finite element (FEM) simulation of power transformer susceptibility to geomagnetically induced currents (GICs). DC saturation patterns for five different transformer core designs are examined using FEM. Magnetic fields along various traverses are provided. Impedance matrix entries of a single-phase power transformer are compared for normal and DC saturation operations. The fundamental transformer magnetization mechanism under GICs is discussed.>