Numerical Calculation of Circulation Current in High Voltage Submarine Cable Grounded with Segmented Interconnection

In the operation of a single-core submarine cable, an alternating current in the cable will generate an alternating electromagnetic field, which results in induction voltages in the metal sheath and steel armor of the cable. When the metal sheaths and steel armors of the submarine cables are grounded at both ends with several connection points in the middle, the metal sheaths and steel armors will generate circulation currents, which will yield Joule losses, influencing the thermal safety of the cables. Consequently, it is essential to study the circulation current in high voltage submarine cables. In this point of view, an equivalent circuit model of the circulation current of the sheath and the armor is first established, and the circuit parameters in a typical laying condition are then calculated by using finite element method. The circulation currents for a case study are calculated. The numerical results show that the induced circulation current in the steel armor is apparently larger than that in the metal sheath, and both are proportional to the value of core current.