Determination of Geomagnetically Induced Current Flow in a Transformer From Reactive Power Absorption

This paper proposes a technique to estimate geomagnetically induced currents (GICs) in a transformer by measuring its absorbed reactive power. GIC is induced in electrical transmission lines by changes in the earth´s magnetic field typically caused by solar magnetic disturbances, and flows into transformers through neutral grounding connections. An assessment of GIC from readily available reactive power measurements is an attractive alternative to the installation of dedicated GIC monitoring equipment on every transformer of an high-voltage transmission network. This technique is verified with electromagnetic transients software simulations and shows good agreement with the historical records captured in Hydro One´s GIC detection network during the May 15, 2005 geomagnetic disturbance.