Screening for HVDC system core saturation instability

Core saturation instability is a condition resulting from excess low-order harmonic AC/DC system interactions, amplified by increasing transformer flux offset which, in turn, is driven by the interaction between the harmonics and the converter. A small signal analysis method has been successfully applied to efficiently screen a variety of conditions for core saturation instability. The screening measures have been defined in terms of the DC system driving point impedances.