Harmonic analysis of the converter stations modulated by GIC in HVDC transmission lines

Geomagnetic induced current (GIC) which the geomagnetic storm brings to the power networks can impact the power systems operators, it is necessary to study whether GIC will bring China high voltage direct current (HVDC) transmission systems and ultra-high voltage direct current (UHVDC) power transmission systems serious harms. The models of transfer function which is an effective harmonic analysis tool on the harmonic transfers between the sides of the converters, considering with the dc currents modulated by GIC in the HVDC transmission lines, the deviations of the firing angle and commutation angles of the converter valves are put forward in the paper. The harmonic characteristics of ac currents of the converters are calculated based on the models, and some conclusions are given out.