Numerical and Analytical Modeling of Electromagnetic Fields From Offshore Power Distribution Cables

The rapid proliferation of power-sharing interconnectors and offshore wind farms has brought with it the need for assuring compliance with regulatory requirements. One regulatory requirement for both federal and state permitting is the evaluation of quasi-static, extremely low-frequency (ELF) electric and magnetic fields (EMFs) from proposed power cables that bring electricity from offshore utility projects to shore. The three power cores of alternating current (ac) cables twist helically around one another within a single cable. Here, ELF magnetic field model calculations are provided, using both numerical and analytical approaches, in the vicinity of submarine power cables in a helically twisted three-core configuration. The numerical simulations were performed by finite-element analysis (FEA) and substantiated with analytical solutions for the same cable geometries. The methodology described here represents a sound approach to conduct such analyses—providing an upper bound on the resulting field values without computationally demanding metallic screening parameters—and demonstrates the feasibility of using a combination of analytical solutions for simpler geometries in conjunction with FEA for more complicated cable paths.