Lightweight, fatigue-resistant power cable developed for underwater power transmission in Joint Industry Project led by BPP-TECH. Offshore subsea power transmission in dynamic conditions has recently become cheaper and easier, with the announcement that the 'PowerCab' JIP has successfully developed a light weight, cost effective, subsea power cable.
Advances made in material selection, design optimisation and modelling techniques have allowed the JIP participants to unveil a fully tested 100MW, 132kV dynamic AC power cable designed for a 525A current carrying capacity.
The cable boasts several material selection innovations, including three conductor cores made from a high performance aluminium alloy. Also used is a special grade of high voltage XLPE insulation material, with its thickness optimised for increased flexibility and reduced size and weight.
Component distribution and lay geometry has resulted in a torsionally balanced cable design with low residual twist and resistance to looping during installation.
"Despite high levels of understanding in the area of static (non-moving) subsea power cables, one of the weak links in the power transmission system was the cable linking the floating production facility with the static seabed cable - the electrical equivalent of a pipeline riser. It is this particular technology gap that was successfully addressed by the PowerCab JIP," says Darren Patel, lead engineer on the PowerCab Development Team and Director of BPP-TECH.
"The availability of this technology will transform the economics of dynamic cable power transmission in offshore oil and gas installations, as well as having a profound impact on many renewables developments," Darren adds. "Benefits will include the removal of power generation equipment from offshore platforms, interconnection of offshore installations, the utilisation of stranded gas for power generation, and the transmission of power to land from moving renewable energy devices."
Another key advantage of this cable in comparison to existing dynamic cables is the reduction in costs achieved through selecting lighter materials, and in optimising their sizing so that the cable is not over-engineered. This has led to the decision to create a separate company to commercialise this technology - called BPP-Cables.
"Rather than providing generic, off-the-shelf cable designs that are adequate for many situations but perfect for none, we can take this technology and optimise it for a client's specific conditions, eliminating unnecessary components, optimising material quantities, and ultimately providing better, longer-lasting cables," says Darren.
BPP-TECH led the PowerCab JIP on behalf of BG International Ltd., BP Exploration, DUCO (Technip), Shell UK and Norske Shell.