The record-breaking 32-MW subsea compression system for Ormen Lange is in its final delivery stages and recently reached a major testing milestone. The power system, a gamechanger for large-scale subsea processing equipment and the world’s longest subsea power step-out, has now been successfully tested in a full-scale dynamic test arrangement. The compression system, which comprise of four 8-MW multiphase compressors, each containing two contra-rotating motors, will be supplied from two onshore Variable Speed Drives (VSD). The step-out distance is 120 km, which is close to three times longer than any existing variable frequency step-out. Onshore VSD output transformers will increase the voltage to enable long-distance transmission, while subsea step-down transformers will transform the voltage back to the motor voltage.


This power configuration with delivery equipment has now been tested at the state-of-the-art facilities at Horsøy in a unique 16-MW test arrangement. The test setup includes an actual compressor, two regenerative back-to-back motor/generator arrangements, subsea transformer, umbilical cable simulator, and onshore equipment. The full-scale test confirmed excellent performance for all load and transient conditions and has given invaluable added confidence in overall performance before the system is installed at the field.


This presentation will share insight to the evaluation and confidence steps taken, from concept idea and analysis, to system verification testing and execution of the dynamic full-load test for one of Norway’s most important and innovative subsea gas developments.