Validation of geomagnetically induced current modelling code

A paper by Horton et al. (2012) details a test grid containing 8 substations with 15 transformers connected by 15 lines. The paper gives detailed information about location, resistances and connections including features such as capacitors, delta and composite transformer types. The model output for 1 V/km in the north-south and east-west directions are provided. In early 2017, the BGS Geomagnetism team produced an equivalent model using the Nodal Admittance Method and proved their model to be consistent with Horton et al. This report outlines our approach and results.