Numerical Simulation of Dynamic Cable Used For Floating Offshore Substation

Abstract

In this study, an area of relatively shallow waters (about 50 meters to 100 meters of water depth) was selected for the designing of a floating substation, and a barge type platform was used to provide sufficient space on the platform for the substation main body space configuration. A catenary mooring system was used to restrict the movement of the platform to a range, in order to avoid random drifting exposing nearby marine structures and navigation channels to danger. In terms of power transmission, the research is aimed at finding the tension and curvature of the dynamic cable under extreme sea conditions in Taiwan. Dynamic cable under different water depths, different cable buoy configurations, and different directions will be observed. After numerical calculations, it is found that the 100-meter deep dynamic cable configuration is more appropriate for installation than the 50-meter deep dynamic cable configuration. As there is more space for the cable to be compressed or stretched, the improved dynamic cable can be applied to the water depth of 100 meters in this research. With the water depth of 50 meters, the dynamic cable can be placed closer to the seabed or to configure cable in a double wave shape, so that the space for cable movement can be increased horizontally. However, even with the improved configuration, only the downstream direction cables of case 2 and case 3are maintainable. Moreover, the failure location of dynamic cable is different under configurations with different angles. With the 0-degree configuration, the touchdown point of dynamic cable is prone to torsional deflection, which causes excessive curvature. With the 90-degree configuration, dynamic cable on the seabed is displaced with a large range. Under the 180-degree configuration, the S-shaped curve configuration of dynamic cable disappears, which causes the tension to increase. These phenomena can be used as a reference and improvement direction for dynamic cable design in the future.