An onboard, autonomous power system was required to supply electricity to a floating LNG (FLNG) plant anchored offshore the state of Sarawak in Malaysia. The power system together with its ancillaries were designed to be reliable and robust enough to operate an LNG plant located 180km offshore while sustaining a crew of 140 people.
The design of the power system started by estimating the amount of power required by the plant. The distribution of loads was then decided and system voltages were selected. The voltage of power generators was then matched with the selected system voltage either through direct connection or via unit transformers. This resulted in different design options which when combined with a plant constrained by limited space and weight as in the case of FLNG, presented unique design challenges.
System studies were carried out together with protection coordination to ensure system stability. The results concluded that the power system will remain stable during a three-phase fault at the highest system voltage. In the event of a total power outage, the electrical system was designed to safely shutdown the plant and then restart it to resume production.
The power generation system at the topside was installed on the floater at the dockyard. All electrical systems were tested prior to sail-away. The load-testing of the GTG's at the dockyard would have incurred substantial cost in terms of the fuel, load bank rental and supporting services. After careful consideration, it was decided to carry out the load tests offshore at the production location.
The unique design of the electrical system for the Floating LNG plant will provide a reference for future, similar projects. The lessons learned will serve to improve future designs in this niche technology.