Application of geomagnetic disturbance vulnerability assessments using the eskom main transmission system model

Severe Geomagnetic Disturbances pose a potential risk to power system operations and assets. Eskom initiated a Solar Storm Resilience Project to prepare for low probability solar events that might have a high impact on the interconnected power system (IPS). The project includes pre- and post-event management plans for solar storms identified to be a significant threat. To support this effort, system studies are needed to identify system vulnerabilities as well as evaluate prospective mitigation measures. The development of a representative system model for the Eskom transmission system using state-of-the-art tools and asset models is presented in this paper. Additionally, findings based on preliminary evaluations of GIC flows and the potential system vulnerabilities are discussed. In particular, the study examined potential steady-state voltage and reactive power margin impacts along with their underlying drivers. While harmonic and heating impacts were not directly evaluated, the equivalent dc model and calculated GIC serve as the foundation for these analyses. Discussion of potential mitigation options is also provided along with general considerations for a comprehensive vulnerability assessments related to GMD driven contingencies. Finally, steps to accurately calibrate and validate the assessment models are outlined.