Study of sheath circulating current and loss-reducing of 500kV long-distance submarine cables

Considering large charging capacitors and grounding feature of 500kV long-distance single-core oil-filled submarine cables, a new calculating method on circulation currents of sheath is proposed based on electromagnetic field theory and circuit laws. With the distributed parameter model of the wire core, the influence of current distribution along core wire and capacitance current on sheath circulation current is analyzed. The cable sheath losses can also be calculated conveniently. The results from on-site test demonstrate the feasibility and effectiveness of the proposed method. Further by analyzing the influence of the structural parameters and operating conditions of submarine cables on cable loss, multi-point grounding of sheath and reactive power flow optimization would be suggested as two effective loss-reducing measures for such kind of projects.