Effects of Series Compensation Capacitors on Geomagnetically Induced Currents

A series compensation capacitor bank presents a high-impedance path to geomagnetically induced currents (GICs), which are induced into the power network during geomagnetic disturbances. The notion that a series capacitor generally blocks GIC is only true for the transmission circuit connected in series with the capacitor. In many cases, the series capacitor simply re-distributes GIC in the network and may actually increase GIC flow at terminal stations. The conditions under which an increase in GIC can take place and illustrative examples with and without piecewise layered earth modeling are discussed.