A new type of compressor motor drive and electrical transmission system will be installed on a Norwegian offshore platform in the North Sea. New compressors are required to compensate the declining reservoir pressure and boost the gas capacity through the pipelines to mainland. The variable speed drive systems consist of two 56 kilovolts, 40 MW synchronous Gable wound motors and two directly connected high voltage direct current transmission lines, which are powered from mainland. The electrical drive system will increase and secure the gas production at a higher efficiency than conventional gas turbine driven compressor systems and avoid emissions of environmentally harmful substances from the platform. The equipment in the electrical drive systems were under test during 2003 and are delivered for assembly on the mainland, after which it will be shipped out to the platform. The drive systems are scheduled for installation in 2004, and commissioning in 2005. The application of a variable speed drive on a platform powered from mainland and utilization of a new combination of electrical cable wound motor and high voltage source converter, have required accurate analysis and design and thorough testing of the motor.
