A Novel Method of Detecting Asymmetrical Transformer Core Saturation Due to Gic

A device based on the sensing of a unique symptom of sustained asymmetrical core saturation of a power transformer, due to geomagnetically induced currents (GIC), and thus indirectly indicating the presence of GIC in an EHV transmission line system, has been developed. The device can be used to achieve any of the following objectives: (1) As an alarm to permit the power system operator to take remedial measures if necessary to prevent further system disturbances during a severe geomagnetic storm. (2) As a control signal for inserting a preventive device designed to eliminate GIC-flow in the system. (3) As a blocking signal for preventing misoperation of existing protection schemes. (4) As an informative alarm signal for a false trip (if any) due to GIC, allowing the system operator to decide on the possibility of fast restoration.