Thruster assisted position mooring system for turret-anchored FPSOs

A thruster assisted position mooring system includes different control functions for station keeping and motions damping of the horizontal-plane motions. A new nonlinear passivity-based state observer producing the thruster control actions has been implemented and verified in full-scale tests. Even though sophisticated filtering and control techniques are applied in the high-level control systems, unforeseen load peaks caused by process disturbances acting on the local actuation system may challenge the power plant stability, if no proper precaution is taken. Both high and low level control aspects concerning integrated positioning and electrical propulsion system are addressed.