Protection of power transformers against the effect of magnetic storms
In the operation of large-scale power systems for the long-distance transmission of large amounts of electricity, a number of cases have been reported in which anomalies in the Earth's magnetosphere, referred to as geomagnetic storms, have caused a severe system collapse. Changes in the geomagnetic field cause a semi-saturating phenomenon, in which the high-voltage lines and especially the high-voltage windings of the power transformers of the system are overloaded with current and subsequently also thermally. The present article briefly explains the physical nature of magnetic storms and then describes a new device that either eliminates the possibility of a step-down power transformer accident or significantly reduces its effects on the system. The essence of this device are frequency filters, which are connected in parallel to the high-voltage windings of power transformers. At the beginning of a geomagnetic storm, the frequency filter is automatically connected to the system and is automatically disconnected when it subsides. The operation of frequency filters does not require human intervention, acquisition and operating costs are low and their integration into existing power systems is easy.
Keywords: geomagnetic field, coronal mass ejection, geomagnetically induced currents, magnetic semi-saturation, frequency filter