The importance of non-uniform geoelectric fields in calculating GIC distributions

During the ascending phase of solar cycle 24 concern in the power industry regarding space weather has increased significantly. This is driving the development of software tools to estimate GIC distributions in power networks for a given uniform geoelectric field. Typically, geoelectric fields induced during space weather disturbances are spatially non-uniform. This paper shows that for accurate planning and development of mitigation strategies, GIC analysis software needs to allow for specification of non-uniform geoelectric fields. Further, the notion held by power utilities in mid and low-latitude locations that space weather does not pose any risk to their systems is questionable. In this paper a methodology is developed to estimate the distribution of GICs in a specified power network during a significant geomagnetic event at mid-latitudes.