Harmonic Anomalies Due to Geomagnetically Induced Currents as a Potential Cause of Protection Mal-Trips at the South Atlantic Anomaly Area

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Abstract
Geomagnetically induced currents (GIC) cause the half-cycle saturation of transformers that inject high harmonic distortion into the grid. Most of the studies cover the analysis of GIC for extreme latitude locations. However, GIC might also impact power grids at mid and low latitudes. Solar energetic particles at the South Atlantic Anomaly (SAA), which covers latitudes between 15° and 45° South, can penetrate deeply into Earth's atmosphere and even reach surface level. Therefore, GIC signatures might be found in harmonic measurements in power grids at SAA. Moreover, the high harmonic distortion can even lead to the mal-trip of protection relays at SAA. This work extracts anomalies in long-term harmonics measurements in a transmission grid (525 kV) in the South of Brazil (latitude 33° South) to evaluate the possible impact of GIC inside SAA. The anomalies are extracted by a deep learning method in combination with expert rules. The harmonic anomalies are validated by cross-checking with Space Weather data and the simultaneity with anomalies in Sweden (latitude 63° North). The main contributions of this work are: (a) validating that the signatures of harmonics due to GIC at SAA are similar to the ones extracted in high latitude; (b) demonstrating that anomalies in harmonics due to GIC are a potential cause of protection mal-trips at SAA.

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