Preliminary modeling of geomagnetically induced currents in South Africa using PowerWorld Simulator

Geomagnetically induced currents (GICs) have received increasing attention in scientific and engineering communities since 1989 due to their effects on electrical infrastructure. Geomagnetic disturbances (GMD), initiated by plasma ejections from the Sun, induce low frequency (<;1 Hz) quasi-dc voltages in transmission lines, causing GICs to flow through neutral-grounded star-wound (grounded-wye) transformer windings. Half-wave saturation of the core causes unbalanced currents, harmonics, localized heating and an increase in non-active power consumption, leading to tripping of protective relays and system instability. South African experience of power system disruption by GICs, even in its mid-latitude location, has been reported and initiated several studies. This research, using the PowerWorld Simulator software, extends previous studies to assess the GICs, voltage stability and reactive power requirements of a model network typical of power systems in South Africa, when subjected to the benchmark GMD event.