Estimating Capacitive Grounding of Power-Transformer Neutrals to Protect Against Geomagnetically Induced Currents

The paper dwells upon a typical circuit used for transmitting power from a remote power plant to the bus bars of a high-power grid that uses capacitive grounding of the power transformer neutrals. It is shown that in case of capacitive grounding, the neutrals parameters depend on the degree, to which the line-to-line voltages are asymmetric. The research team has designed a zero-sequence equivalent circuit that relies on the zero-sequence parameters, including the capacitive resistance of capacitor batteries in the power transformer neutrals. The paper proposes a quantitative criterion to configure the parameters of the capacitor batteries used in the capacitive grounding of power transformer neutrals, which prevents resonance.