Subsea High Voltage Substations for Floating Offshore Wind Applications

Abstract Over the last few years, the oil and gas industry has been challenged by prolonged volatile hydrocarbon prices and market instability. As a direct consequence of these challenging conditions, the industry has experienced a shift of focus to the development and application of more advanced and efficient technologies. One of the most revolutionary subsea technological developments implemented in the latest years has been the subsea compression system installed at the Åsgard field, located offshore Norway. It has successfully been in continuous operation since September 2015. This has proven the feasibility of installing a compressor on the seabed, and at the same time verified a large number of power and control system technologies required for the control and operation of the subsea compressor. This includes large subsea transformers, power cables and terminations and high voltage wet-mate connectors, all of which are essential technologies for subsea substations for offshore wind application. Today, the rapidly expanding offshore wind power industry could benefit from utilizing some of these high voltage power techonlogies recently qualified for subsea oil and gas processing applications. Many of the subsea power technological developments, skills and expertise gained in the oil and gas industry can be adapted for offshore wind application. This paper presents the concept of a subsea high voltage substation applied to floating offshore wind parks. Both the system characteristics and the individual power technology features that are required to make the substation compact, efficient and reliable are emphasized. In addition, the differences and benefits of a subsea substation versus a floating substation will be highlighted.