Utilizing magnetotelluric and differential magnetometer measurements for the validation of geomagnetically induced current models in a complex power network

Space weather as a geohazard to modern technological infrastructure has come to the forefront of electromagnetic research in the past years. Geomagnetically induced currents (GICs) are generated by the rapidly changing magnetic fields during geomagnetic storms and sub-storms and the resulting induced electric fields into the ground. GICs can pose great risk to e.g. transformers in HV power grids and their monitoring and modelling is an ongoing effort in many higher and mid-latitude countries. Modelling of GICs in HV power grids requires knowledge about the magnetic field variations, the induced electric field via a conductivity model or through the magnetotelluric (MT) impedance tensor, and a detailed representation of the grid topology.

In the UK we have traditionally used a thin-sheet model for the calculation of electric fields during storm times due to very limited availability of MT data, but also as a fast and computational cost-effective approach. Using the Differential Magnetometer Method (DMM) in several locations of the grid has enabled us to indirectly measure GICs and validate them against the model. Here we present a case study from a location in Scotland, where we incorporate the different approaches and data sets that combine to a comprehensive analysis of GICs in this subset of the UK power grid.