Harmonic transfer in HVDC systems under unbalanced conditions

The harmonic interaction between AC- and DC-systems has been discussed in various publications with respect to both characteristic and noncharacteristic harmonics injected into AC-power transmission systems by HVDC converters. This paper presents a method to determine the transfer of harmonics from the supplying AC network to the DC system and vice versa. The imbalance in both fundamental and harmonic voltages is introduced in the mathematical model by the corresponding symmetrical components, e.g. by their positive and negative components. The method presented is valid for both power flow directions.