Time domain analysis of the impact of geomagnetically induced current on power system
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To understand the impact of geomagnetically induced current (GIC) on power system equipment, a time domain simulation based analysis is proposed. This analysis starts with developing the device models in time domain considering the effect of GIC, such as transformers saturation and harmonics flowing through transmission lines. A set of physically based models are developed in this dissertation including a low-frequency broadband model and transformer models with detailed magnetic circuits. The union of these models provides an accurate computation of quasi-DC current flow and harmonics during a GIC event in the time domain. The results of the time domain simulation are utilized towards a further analysis of the impacts of GIC. The directional sensitivity of power grids to geomagnetic disturbances (GMD) and the transients of GIC are investigated. The performance of the protection scheme and instrumentation channel error during GMD are examined. The results demonstrate the advantage of the time domain based GIC analysis, which captures all the relevant transients, while conventional GIC analysis ignores detailed transients occurring during GMD activities, including the rise of GIC at the beginning of GMD, the variation of the flux in different transformer configurations, the increase of instrumentation channel errors, and the mis-operations of legacy protective relays.