Potential impacts of harmonics on bulk system integrity during geomagnetic disturbances

Asymmetric saturation of transformers occurs during geomagnetic disturbances, causing large exciting currents that include both fundamental and harmonic components. The harmonic components can aggravate the system stress produced by the fundamental reactive currents, by causing loss of real and reactive power resources, increasing reactive demand, causing faults and decreasing the system's robustness. This paper describes the injection and propagation of the harmonic exciting current components, and the resulting impacts on the bulk power system and its equipment.