Thermal Rating of Offshore Wind Farm Cables Installed in Ventilated J-Tubes

Abstract

The section of submarine cable that is installed in enclosed J-tubes represents a possible thermal limiting point along the export circuits of offshore wind farms (OWFs). To obtain higher continuous thermal ratings for J-tube systems, a ventilated design, realized by allowing for the flow of natural wind into the J-tube through vents, is considered in this paper. To evaluate the performance of this forced-ventilation design, a coupled three-dimensional (3D) numerical model is constructed using the computational fluid dynamics (CFD) technique. The CFD method is first successfully tested through comparisons with existing methods for enclosed J-tubes. Then, the cable rating for the ventilated design is determined using the CFD model and compared with the rating for the enclosed case. The results show that the cooling effect from forced ventilation is obvious, and the cable rating could be increased by up to 27.5% for a wind speed of 10 m/s. This improvement in rating is especially significant for OWFs where the export circuit output is limited by the cable rating in enclosed J-tubes.

Calculation of Equivalent Resistance for Ground Wires Twined with Armor Rods in Contact Terminals

“…To investigate the characteristics of the steady-state temperature distribution in the contact terminal, a series of steady-state temperature rise experiments were performed on a contact terminal consisting of the 50 mm 2 ground wire with a length of 7 m and corresponding armor rod with a length of 1.3 m, as shown in Figure 11. The experimental setup is shown in Figure 11a, where the experimental system consists of three parts: the current generation loop, the feedback control loop, and the experimental load [24][25][26][27]. The current generation loop was comprised of a 380 V power supply, a voltage regulator, a current generator, and a compensation capacitor.…”

A Model for the Thermal Behaviour of an Offshore Cable Installed in a J-Tube

“…In particular, he proposes a study of the influence of the upper and lower sections on the emerged tube. You [9] proposes a numerical simulation of an air vent on the cooling of a J-tube, via Fluent, which could be one of the possible technical solutions, although this simulation is not compared with experimental measurements for validation.…”

“…Better exchanges by convection inside the tube would undeniably allow better cooling of the cable. Here we have limited ourselves to natural convection ( 2 Wm K < ℎ < 10 Wm K ), but it is obvious that allowing forced convection, by creating air circulation for example, would greatly improve the ampacity of the cable [9].  Additionally, it would be interesting to know how important the improvement of the cable temperature could be if we had the ideal configuration, as p = 0.4 m ; ε = 1 ; ε = 1 ; ε = 1 ; α = 0.2.…”

A New Method for Determining the Connection Resistance of the Compression Connector in Cable Joint

“…A number of methods have been employed to calculate the contact resistance in the literature including finite element analysis (FEA), experimental measurement, and electrical contacts model analysis (ECMA) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In the FEA method, some researchers have added an extremely thin film on the contact interface of the two connectors.…”

“…However, in the above methods, the stranded conductor was simplified as a single cylinder to save computing resources and pursue convergence [11,[13][14][15]. To attain an accurate calculation of connection resistance, it is necessary to fully consider the stranded and compressed structure of the cable conductor, the local plastic deformation of the ferrule, and the actual contact interface between the ferrule and the cable conductor.…”