Secondary arc effects in AC/DC hybrid transmission

Adding a DC circuit to an existing AC transmission line or replacing one AC circuit with a DC circuit is one method of significantly increasing the power transfer capability of the transmission line. Coupling at fundamental frequency from the AC circuit to the DC circuit on the same tower interferes with the clearing of DC line faults. Even though DC current in the fault arc can be brought to zero by the controls of the DC transmission systems, fundamental frequency secondary arc current can delay clearing of the fault. The factors which impact the duration of secondary arc are investigated for both balanced and unbalanced conditions on the AC circuit