基于推进器偏置的半潜式平台动力定位模型试验研究

Experimental study on a semi-submersible platform DP system based on thruster biasing

半潜式平台在进行动力定位作业时,由于其水线面面积较小而初稳性高较低,其垂向运动(横摇、纵摇、垂荡)易受到推进器法向力作用的影响。基于此,提出一种基于推进器偏置的推力分配模式,旨在合理利用推进器的法向力抑制平台垂向运动,而不影响平台水平面定位功能。在海洋工程水池开展半潜式平台的动力定位模型试验,对比和分析不同载荷工况及推进器偏置模式下平台的六自由度运动响应。结果表明,推进器偏置策略能够基本保证水平面定位精度,并显著减小平台垂向运动在其固有频率附近的响应幅值,在该试验工况下,功率谱密度(PSD)峰值减小高达54.7%,对波频区间的运动影响则较小。该研究结果可为半潜平台垂向运动抑制提供新思路。

For semi-submersible platforms equipped with dynamic positioning(DP)system,which has a small water-plane area and low metacentric height,vertical motion(roll,pitch,heave)will be affected by the normal control force of the thrusters.In light of this,this paper proposes a novel thrust allocation method based on thruster biasing,which aims to suppress the vertical motion and ensure the positioning accuracy of the horizontal motion.Model scale tests are conducted for the dynamic positioning of a semi-submersible platform in the ocean wave basin,to analyze and compare the six-degree-of-freedom motion responses under different environmental loads and thruster biasing configurations.The results show that the thruster biasing strategy can ensure the ability of station-keeping and significantly reduce the response amplitude near the natural frequency of the vertical motion of the platform,the reduction of the power spectrum peak is up to 54.7% under the given test cases,while the vertical motion in the wave-frequency is unaffected.The research results give a novel idea for the control of semi-submersible platform vertical motion.