Exploring Deep Water Applications for Offshore Renewable Power Systems

Abstract

Abstract The increasing power output of today’s renewable energy generation devices mean there is a growing need for affordable, dynamic, high voltage subsea power cables. Serendipitously, these solutions are directly relevant to the offshore oil and gas industry, specifically when coupled to power distribution hubs for processing and boosting at the evolving subsea factories. It’s been challenging for the industry to identify an affordable and yet highly reliable solution that provides high power, deep-water, long length subsea power cables capable of continuously flexing. The entry of new dielectrics for higher alternating electrical stress means there are now solutions for these technologically complex and incompatible demands. However, both direct current (DC) and alternating current (AC) systems have benefits and limitations when used for offshore power systems. DC systems offer a proven solution to transmit high power over long distances between two points. Yet, DC systems are neither ideal for multi-node topologies nor for end-to-end connection, especially when including conversion of mechanical energy into electrical energy (generation), switching, connectors, protection and final conversion of electrical energy back into mechanical work (eg motors). AC systems offer the possibility of easy and efficient conversion and delivery using the most appropriate voltage across each selection of the network, from the generation through transmission, distribution and control, all the way through to the voltage needed by the motors and other loads at the far end. This paper will significantly advance research and development efforts in dynamic subsea power cable technology and help progress offshore renewable energy technologies by championing the consideration of system needs before cable design. It discusses the benefits and limitations of alternative cable designs for subsea power links, supported by results from sample and full scale testing of a 72 kV subsea cable design, using concepts suitable for dynamic application. The International Council on Large Electrical Systems (CIGRE) and the International Electrotechnical Commission (IEC) are considering creating standards and this paper proposes a basis for this.