Study on the Calculation and Suppression Method of Metal Sheath Circulating Current of Three-phase Single-core Cable

Due to the inconvenience of transposition of submarine cable, the metal sheath will produce a higher induced voltage, which will cause a larger metal sheath circulating current. The excessive circulating current will increase the cable heat and hence shrink the cable transmission capacity. Based on the basic circuit theory, this paper deduces the transmission equation of three-phase cable and then puts forward a calculation method for the terminal current in metal sheath. The high accuracy of the proposed method is verified by through PSCAD. Furthermore, since the circulating current level in submarine cable is too high, we first compare the circulating current value under three different grounding scenarios and then propose a novel method, i.e., directly grounded on both ends of the cable sheath with the middle section of multi-point grounding method, to alleviate the excessive circulating current. Simulation results demonstrate the effectiveness of the proposed method in suppressing circulating current.