Magnetic Field Estimation in AC Three-Core Armored Power Cables

The rapid growth of offshore renewable energy projects has led to the increased usage of submarine cables, which are necessary for the power transmission to the mainland. In their majority, these are AC, three-core (3 C) armored power cables. The environmental impact of such cable installations has not been fully evaluated yet, although concerns have been raised about potential harmful consequences on the balance of natural ecosystems due to the emitted magnetic field. The armor existence and the twisted cable geometry make the magnetic field calculations in the vicinity of such cables more challenging than existing analytical methods which only consider straight or helically twisted conductors. Other, existing works account for the cable twisting effects when computing the field produced by AC, 3 C armored cables via numerical methods. A more accurate numerical method, accounting for the field-dependent magnetic permeability, is suggested in the present paper. The problem of magnetic field calculation around the cable is approached also analytically and a sufficiently accurate, faster solution is provided. Both methods are validated against experimental measurements, achieving an agreement better than that cited in the literature. Various design aspects, such as the conductor size, armor magnetic permeability and armor lay length, are also discussed.