Selection and Tests of Innovative Variable Speed Motor-Compressor Solutions for a 55MW Full Electric Offshore Platform Maximizing Availability and Efficiency with Better Environmental Impact: Copyright Material IEEE, Paper No. PCIC-2018-07

A new concept of an electric off-shore platform, sized to 55 MW, which is powered from 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 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 compact filter and robust control, the gearless rotating equipment combining a TEWAC induction motor and a compressor on active magnetic bearings operating up to 7 MW @ 14500 rpm. 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.