Thrust allocation with power management functionality on dynamically positioned vessels

A thrust allocation method with capabilities to assist the power management system on dynamically positioned ships is proposed in this paper. Its main benefits are reduction in frequency and/or load variations on the electric network, and a formulation of thruster bias which can be released when required by the power management system. To reduce load variations without increasing overall power consumption it is necessary to deviate from the thrust command given by the dynamic positioning system or joystick. The resulting deviation in position and velocity of the vessel is tightly controlled, and results show that small deviations are sufficient to fulfill the objective. For simplicity, the study has been limited to thrusters with fixed direction, having in mind that generalizations are fairly straightforward.