More and more emphasis is being put on the examination of geomagnetic storms nowadays. Storms are caused by the solar activity that results in charged particles moving from the Sun towards the Earth. Then the stream of charged particles causes disturbances in the Earth’s magnetosphere resulting in the flow of low frequency current in large metal constructions found on the earth (such as power system's transmission lines). This current created by geomagnetic impact is called Geomagnetically Inducted Current.
The purpose of this study is to present briefly the way how GIC is created, and to examine its effects on the power system. In my paper I am going to reflect on issues concerning GIC in the past, and I have also conducted simulations on networks of different complexity levels in the purpose of quantifying the problem. The first simulation is simple, it includes a two node network in which I was observing the impacts of different storm and system parameters. In the second simulation I created the model of an American network that is not yet built, but may come into reality in the future. On this network with nominal voltage of 765 kV I examined the expected numbers/rates of GIC on the basis of the parameters of a storm that has already occurred in the past. In the third simulation I extended the previously mentioned network in a way of forming it into a looped network and I analysed the effects of GIC on the looped system. The results of simulations show that the problem is real, it must be taken seriously, since on the basis of the given outcomes a GIC of about ~400 A is able to flow through the earth of the transformer star point which can lead to transformer saturation or damage.