Geomagnetically induced currents: A measurement based inverse determination of earth impedances

Geomagnetically induced currents (GIC) can lead to serious disturbances in transmission grids. Arising problems range from high noise levels and reactive power consumption of transformers up to transformer outages and regional blackouts. To mitigate GICs effectively, simulation is an important aspect. However, incomplete electrical grid data in combination with discrete earth layer models lead to differences between measurement and simulation. In this article, we describe an inverse calculation method of the complex earth impedance, based on transformer neutral point measurements.

The figure shows a comparison of the calculated electric fields with the standardized earth models and the inverse calculated fields. The resulting GICs of both methods are compared with transformer neutral point measurements from in the Austrian power grid. 

We show that the resulting inverse earth model leads to higher simulation accuracy. This calculation method may be used especially when earth layer data is missing or inaccurate.

This work was presented at the 56th International Universities Power Engineering Conference (UPEC).

DOI: 10.1109/UPEC50034.2021.9548157