Protecting Radial Electric Grid from Geoinduced Currents

Possible ways of protecting radial topology electrical grids from the geoinduced currents (GIC) impact are considered, both by operational switching and by including capacitor banks in the neutral of power transformers. The authors suggest a method for estimating the GIC values in the neutrals of power transformers of an electric grid. It allows accounting for the direction of the geoelectric field intensity vector and the spatial location of power transformers. Possible operational switchings to reduce the vulnerability of power transformers of the radial topology electrical grid are considered. The principle of the capacitive grounding operation is given to protect a power transformer from the GIC effects by switching a capacitor bank into neutral. The research defines the conditions where using one capacitor bank only may block the possibility of GIC flowing in the neutrals of all power transformers of the radial electric grid. The article provides the quantitative examples of GIC calculating without capacitive grounding and at the capacitor bank switching, which confirm the possibility of protecting power transformers from the GIC effects using a minimum number of capacitive grounding points.