Second harmonic based method to detect geomagnetically induced currents in power transformers

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University of New Brunswick


Geomagnetically Induced Currents (GICs) are quasi-dc currents triggered by inter-actions between the Earth’s magnetic field and charged particles released by the sun during coronal mass ejections. These currents flow through grounding circuits (such as grounded power transformers) into power systems, and can damage power system components. A power transformer with a GIC flow experiences half-cycle saturation, causing harmonic distortion and increased reactive power demands. As a result, power transformers can suffer damage, mal-operation of protective devices, tripping of compensation devices, and degraded power quality. Various methods have been developed to respond to GIC flows, the majority of which identify the need for blocking of GIC flows. To block GIC flows, a method to accurately detect GIC is required. This thesis focuses on the development of an effective measure to detect the GIC flow. The desired detection measure is based on the second harmonic component extracted from power transformer differential currents.