Impact of Geomagnetically Induced Currents on Transformers in the Kola Power Grid

Transmission lines in high latitudes are exposed to geomagnetic disturbances. The geomagnetically induced currents generated by these disturbances in the overhead lines and transformer windings may saturate transformer cores and lead to disoperation of power systems. The results of long-term neutral currents monitoring in a Kola power system transformers are analyzed. It has been experimentally confirmed that the geomagnetically induced currents causes saturation of the power transformer core. This leads to an increase in the level of harmonics in the current of the windings, which can cause both heating of the transformer and the malfunction of relay protection and automation devices.