Selection and Tests of Innovative Variable-Speed Motor–Compressor Solutions for a 55-MW Full Electric Offshore Platform Maximizing Availability and Efficiency With Better Environmental Impact

A new concept of an electric offshore platform, sized to 55 MW, which is powered from the shore via a 161-km subsea cable, is currently being commissioned in the North Sea. Only electrical motors drive the rotating equipment such as the compressors and the pumps. The first part of this paper overviews the selected global architecture of the electric compression based on three variable-speed direct drive solutions for gas exports in term of flexibility, operability, efficiency, compactness of integration, and environmental impact. The second part focuses on the motor-compressor technology including the 250-Hz voltage-source-inverter drive with a compact filter and robust control, the gearless rotating equipment combining a totally enclosed water-air cooled (TEWAC) induction motor and a compressor on active magnetic bearings operating up to 7 MW at 14 500 r/min. The gas string test results are presented validating the system performance and compactness. The conclusion is dedicated to the next generation of mature solutions using standalone and integrated topside or subsea machine improving the system reliability and operability.