Limitations of the modeling of geomagnetically induced currents in the South African power network

Geomagnetically induced currents (GICs) are known to affect electric power systems in both the midlatitude and high-latitude regions. Monitoring of GICs in the southern African electrical power grid first started in 1998 with the installation of the Electric Power Research Institute Sunburst monitoring system. Recent research efforts in South Africa have shown that the modeling of GICs is effectively improved by the use of a multilayered ground conductivity model and a modified set of network coefficients. This paper reports on an investigation into the reliability of a new GIC model versus the distance between the magnetometer stations and the GIC measuring site using recent developments within this field and the South African context. Results show that the modeling of GICs degrades with increasing distance between the geomagnetic observation station and the GIC site and that the newly developed GIC model is only appropriate for the specific geomagnetic station and GIC site pair. Citation: Ngwira, C. M., L.-A. McKinnell, P. J. Cilliers, A. Viljanen, and R. Pirjola ( 2009), Limitations of the modeling of geomagnetically induced currents in the South African power network, Space Weather, 7, S10002, doi:10.1029/2009SW000478.