Power System Voltage Stability in the Presence of GIC-Like Currents

Geomagnetic disturbances from solar storms create earth potentials that induce quasi-de currents called geomagnetically induced currents (GICs) in power systems. GICs cause half cycle saturation in transformers, which inject harmonics into the power system and exhibit increased reactive power consumption and affect load bus voltage levels locally. This paper seeks to improve the understanding of the effects of GICs on power system voltage stability by using the conventional and General Power Theory approach. A laboratory experiment injecting dc currents into a small power system demonstrated the expected distortion from both odd and even order harmonic components, increased reactive power and a clear trend towards greater voltage instability.