FUEL OPTIMIZED THRUST ALLOCATION ALGORITHM DEVELOPMENT USING PENALTY-METHOD FOR THE DYNAMIC POSITIONING FPSO

In this paper, a thrust allocation algorithm is proposed to minimize the fuel consumption and the gas emission of the offshore platform dynamic positioning system. The thrust allocation algorithm generates thruster commands that keep the position of offshore platform while physical limitation. Generally, the offshore platform control system is an over actuated system. Thus, a thrust allocation problem of the offshore platform can be determined as an optimization problem. In this research, a thrust allocation problem is designed to minimize the fuel-consumption and the gas emission. Fuel-optimal thrust allocation was newly formulated and solved based on penalty-method based optimization. Developed thrust allocation method was evaluated by comparing to conventional pseudo-inverse based thrust allocation. The proposed thrust allocation method was validated with comparison with an offshore support vessel static allocation cases. A fully coupled dynamics of hull, mooring, riser, and dynamic positioning system were simulated in time domain. The proposed thrust allocation method that uses penalty-method achieved a 3% accumulated fuel consumption reduction compared to the conventional pseudo-inverse method based thrust allocation algorithm in GOM 1-yr storm condition.