Mitigation of Transformer Saturation Due To Neutral HVDC Currents

This paper introduces a new technique that provides an efficient mitigation solution to transformer saturation caused by HVDC neutral currents. This solution is not dependent or at most weakly dependent on the network configuration to ensure that the transformer windings dc currents are always below the safe values. An efficient and economical mitigation has been developed based on the new technique to one practical case and the mitigation effectiveness is demonstrated. The computation results reveal that the proposed mitigation system reduces the DC transformer currents by more than 60% for this particular case. Moreover, results show that the mitigation measure proposed also performs safely during the worst fault conditions on the transformers and on the network