Large Power Grid Hazards From Geomagnetic Storms Caused by Solar Activity

The survival of modern human life today depends on energy security, any interruption, e.g., by solar sources that cause various disruptions in the power grids. Special attention has been widely paid to studying the electrical disturbances following the March 1989 event in northern Canada. For this purpose, various countries started several studies to take the necessary measures to reduce the damage caused by geomagnetic storms in the power network. We carefully know that solar activity was considered the principal source of geomagnetic storms. Coronal mass ejections- the huge bubbles of hot plasma and magnetic fields with a speed of about 200 to 1000 kilometers per hour and solar flares are the most important causes of a geomagnetic storm. If they occur toward the Earth simultaneously, they can affect Earth’s magnetic field and cause significant disturbances in the power grids. The solar activity has 11-year periods, but it is not entirely possible to predict the occurring time of solar events. Temporal variations of these currents cause a geoelectric field and low-frequency quasi-static geomagnetically induced currents (GIC) in power grid equipment. Studies in different geographical locations show that the magnitude of geomagnetic induction current (GIC) is directly related to the temporal changes of the disturbing magnetic field and especially to its horizontal component.
Transformers are one of the most effective equipment in a geomagnetic disturbance. In high latitudes, damages to power transformers have been reported in which geomagnetic changes during hurricane times have been very rapid and large (greater than 1000 nT), and hence GICs as large as or greater than 100 amps flow at the end of the storm in the winding. Usually, the geomagnetic disturbances are not strong at low latitudes, so much smaller GICs are reported there. However, the flow of GICs and their effects on power transformers are complex processes, and careful evaluation is required even in such low latitude regions. The strategies used against geomagnetic disturbances highly depend on geographical areas.
Countries that have already experienced the harmful effects of geomagnetic disturbances perform better in an event. Researchers in Russia, Japan, and Brazil proposed algorithms usable in all power grids and any geographical location. Testing the algorithms on the power grids in the mentioned countries confirmed that the magnitude of GICs and their possible harmful effects also depend on the power network topology, resistors, and other engineering details of the power system.
This article reviewed the impressive factors causing geomagnetic disturbances via solar activity and their effects on the power grids. In the logical next step, we will focus on finding the possible hazards in the Iranian bulk power network as linked with several neighboring countries by analyzing the related data.