Effects of geomagnetic storms on long distance AC transmission systems

Solar Induced Currents (SICs) are the cause of many detrimental effects on power systems. It is worth to note that the scientific interest for this topic is cyclical and follows the relevant periods of the solar activity. The large blackout of North East USA and Canada of 1989 linked to a large solar activity definitively marks a milestone in the scientific research and activity in this field. It is also worth noting that sometimes this issue becomes a sort of scapegoat to explain inexplicable phenomena or coincidences as in the case of the numerous blackouts that occurred worldwide in the Summer of 2003, which were improperly related to a particularly high solar activity. In this chapter, we limit our analysis to their effect on long transmission line and the beneficial effect that some new equipment, such as Static Var Compensators (SVCs), can play in preventing malfunction when an appropriate coordinate compensation strategy is applied.