Sensitivities of Geomagnetically Induced Currents in Dominion Energy Virginia to the Neighboring Grids and Transformer Blocking Schemes

Space weather-driven geomagnetic disturbances (GMD) can cause quasi-DC geomagnetically-induced currents (GIC) to flow in the power grid leading to transformer overheating, excessive harmonics, and large reactive power loss. To protect system reliability, system planners are required to perform GMD modelling of their grids and calculate GIC flow in their transformers to assess system vulnerabilities during extreme GMD events. However, the portion of the neighboring networks outside a study area that should be modelled for accurate GIC calculations is often unclear and system-specific. This work adds to this body of knowledge by investigating the sensitivity of GIC magnitudes in the Dominion Energy Virginia (DEV) grid to different levels of neighboring system modelling. It was found that sufficient calculation accuracies of GIC magnitudes and transformers’ reactive power consumption can only be achieved if the GMD model of the DEV grid includes up to the 5
^th
neighboring buses. Additionally, the sensitivity of GIC flow in DEV transformers to GIC blocking schemes within and outside the DEV area were explored. It was shown that blocking GIC in a substation transformer can significantly increase GIC magnitudes in other transformers of the same substation. Thus, GIC blocking schemes must be deployed substation-wide rather than for single transformers. This paper also revealed that GIC blocking schemes in utilities close to the DEV grid can lead to higher GIC in DEV transformers, thus collaboration of neighboring electric utilities is useful for GMD/GIC studies.