Previous studies have presented evidence of geomagnetically induced currents (GIC) damaging high voltage transformers within electricity transmission grids to the point of failure [e.g. Gaunt & Coetzee, 2007]. In the UK, National Grid has estimated that during an extreme space weather event, two large transformers could be catastrophically damaged, leading to disconnection from the transmission grid for potentially two to four months [Oughton et al., 2018]. Consequently, much research focuses on the modelling and measurement of potentially damaging GIC flowing through grid transformers. However, only a small fraction of UK grid transformers are equipped with GIC monitoring sensors. The resulting scarcity of data presents challenges to our understanding of the impact of differing levels of geomagnetic disturbance on infrastructure assets, and to the validation of grid models that might offer a forecasting capability. However, almost all transformers include dissolved gas analysis (DGA) sensors that monitor the status of the unit’s coolant oil to detect indicators of stress or damage. We therefore present the results of a preliminary study, in which DGA data from a number of UK power station transformers between 2010-15 are analysed with respect to geomagnetic activity.

C.T. Gaunt & G. Coetzee (2007), Transformer failures in regions incorrectly considered to have low GIC-risk, 2007 IEEE Lausanne Power Tech, 10.1109/PCT.2007.4538419.

E.J. Oughton et al. (2018), A risk assessment framework for the socioeconomic impacts of electricity transmission infrastructure failure due to space weather: an application to the United Kingdom, Risk Analysis 10.1111/risa.13229.