Statoil runs the Troll oilfield, one of the most important in Norway’s sector of the North Sea. After nine years’ operation it became necessary to boost production by installing two compressors on the immense Troll A platform.
ABB provided these devices with a revolutionary solution. It consisted of an electrical drive system that brought together two ground breaking technologies: the world’s first high-voltage DC power-from-shore connection to a platform and the first commercial installation of very high voltage synchronous motors, each with a power rating of 40 MW.
The solution takes 132 kV power from the mainland grid and turns it into DC at a converter station at Statoil’s Kollsnes gas processing plant. Two HVDC Light power cables, each with a capacity of 40 MW, then transport the power at 60 kV to Troll A, a distance of 70 km. There, the power is turned back into AC by a compact lightweight converter station and fed to the two ABB motors that drive the compressors.
This way of bringing power to the compressors was better than installing gas turbines on the platform – the conventional solution – because the capital, operating and maintenance costs were all significantly cheaper. It also reduced the environmental cost of running the compressors by 230,000 tons of carbon dioxide a year.
Following the success of this project, Statoil selected ABB in 2011 to do much the same for the third and fourth compressors. We are now acting as the engineering, procurement and construction contractor another HVDC Light cable system, complete with onshore and offshore converters, and two motors with power ratings of 44 MW and 50 MW.
These extra compressors will come on stream in 2015, and are expected to extend the productive life of the field to 2063.