Three-Dimensional Simulation of Temperature Rise of a Prototype Conductor in 35kV Offshore Single-Point Mooring Device

The single-point mooring (SPM) system is a critical part of the FPSO device, which can realize the transfer of electrical energy (via the high voltage conductors), communication and control information (via optic fiber) and oil/gas fluids (via tube system) in the marine environment. To enhance the transmission ability of electric power, a relatively higher voltage (e.g., 10–35 kV) and higher current (up to 1000A) can be employed, which however requires detailed analysis on the thermal field distribution. In this study, numerical simulation of thermal field distribution on a prototype of 35kV SPM device was involved. Finite element method was used to calculate the coupled magnetic and thermal field on a simplified SPM conductor system. The results show that the current flow concentrates to the surface of the copper conductors, indicating a relatively strong “skin-effect” caused by self-induction. The temperature rise in the simulation model is 11.58 K for the inlet/outlet busbars and 5.96 K for the sliding rings when 640A(r.m.s.), 50Hz AC current is employed. The comparison between simulation and experimental data indicates that despite the low current (160A) situation, the error between simulated temperature rise to experimental ones are less than 15%, indicating high accuracy of the FEM simulation.