Control system and condition monitoring for a subsea gas compressor pilot

For the Ormen Lange field, a 12 MW subsea gas compressor station pilot is being built. It will be run in a water filled pit on land for 2 years, and (if successful) deployed subsea at 1000 m depth along with 3 more identical stations. The paper describes the plant, the developed control system, the all electric actuators, the subsea power distribution and the system for condition monitoring. The pilot comprises several novel parts for subsea applications, e.g. magnetic bearings for the compressor, all electric valve actuators of different types, a subsea HV Circuit Breaker module, subsea VSDs and subsea UPS modules. The control and safety system are split into completely separated subsystems, and in addition there is a separate system for condition monitoring which collects appr. 1 million data items per second for the 2 years of trial run (giving 100 TBytes of data after 2 years operation). The condition monitoring data is used for design verification, trouble shooting, and monitoring gradual deterioration of the equipment. For the final subsea station, the aim is to use the CM data for planning maintenance in advance Condition Based Maintenance.