Optimal Thrust Allocation For Dynamic Positioning System Of Semi-submersible Drilling Rig

Due to the qualification of fast positioning,easy operation,strong maneuverability,easy operation,and no influence of water depth,the dynamic positioning system has been applied tremendously for the offshore engineering systems such as offshore drilling rig.In the thesis,the dynamic positioning system of semi-submersible drilling rig “Haiyang Shiyou 981” is the research medium to study the improvement of the position capacity of the drilling rig and power consumption of the thruster in the thrust allocation system.The study is based on the genetic algorithm and combination of either simulated annealing algorithm or non-linear programming algorithm.The assumption is if the application of the hybrid intelligent thrust allocation optimization algorithm is superior to the capacity of the thrust allocation system as the result of the study.The hybrid intelligent thrust allocation is capable to stimulate the positioning capacity of the drilling rig and redeem power consumption.Moreover,the working efficiency of the drilling rig is improved enormously.The objectives of the modeling in the paper is for the optimization of the thruster power consumption in the thrust allocation system.Considering the positioning capacity of the drilling rig needs to be calculated and analyzed through live operation tracking,the operation speed is added to the evaluation elements along with the consumption of the thruster power.The two elements mentioned above are the criteria for the optimization effect of the hybrid algorithm.In order to verify the performance of the algorithm,simulation tests were performed to verify the feasibility and effectiveness of the hybrid algorithm,and it shows the performance is better than the single genetic algorithm and single simulated annealing algorithm.The hybrid algorithm is further applied to dynamic positioning system of the drilling rig “Haiyang Shiyou 981” and the simulation tests was performed in the standard of normal working status on the drilling rig along with the failure status of multiple thrusters.The simulation results show that the hybrid intelligent thrust allocation optimization algorithm can effectively complete the allocation with better positioning capacity than neither single genetic algorithm nor simulated annealing algorithm.Meanwhile,the power consumption is less than neither single genetic algorithm nor the simulated annealing algorithm.The simulation research of the hybrid intelligent thrust allocation optimization algorithm can provide certain reference value for the design of the actual engineering thrust distribution system.