Research On Semi-physical Simulation Of Mooring Dynamic Positioning For Semi-submersible Platform

Globalization and growing energy demand forced the offshore structures to work indeeper water and technology innovation. Hence, time-consuming expensive testing is moreand more replaced by computer simulation. Normally, these simulations are based oncomplex physical models describing the dynamic behavior of the structure and its components.This paper discusses the deepwater mooring dynamic positioning simulation which is a meanof semi-physical simulation. It has abilities to simulate the motion of platform, equilibrate thedistribution of force field and coordinate the real and simulated anchor gears.The semi-submersible platform works in severe sea condition through the mooringsystem for a long time. The mooring system contains more than8mooring lines which areconfigured balanced and rapidly. Dynamic positioning system is also equipped for theplatform which requires higher accuracy. The mooring system not only ensure that thefloating body’s motion satisfied requirements in working condition and survival condition,but also avoid collision with ships, platforms or subsea pipe lines nearby regions. Therefore,the application of the simulation of mooring dynamic positioning in marine engineering hasbroad prospects.The simulation system should have the following functions:1. detecting the errorbetween the actual position and target position;2. calculation of mooring line s’ tensions torevert to the original position of platform;3. control instructions are sent to control the anchorfor keeping the position of platform.The research is conducted on a semi-submersible platform which is planned to work onthe South Sea of China with water depth1500meters based on theoretical analysis and analogcalculation.The main work of this paper shows as follows:[1] According to the related information, state of the art of domestic and abroad is studied,then, proposed the modeling and simulation for mooring system with consideration ofdynamic characteristics of coupled motion of platform and mooring lines.[2] Combine with the structure of semi-physical simulation and the equipment of mooringsystem; we proposed preliminary design of simulation system.[3] This paper mainly introduces the user operation system, which is human-computerinterface and data communication.In summary, several aspects based on the mooring system were studies including: general structure design of semi-physical simulation of mooring dynamic positioning,modeling and simulation, design and realization of PC software and so on. The results ofresearch can give reference for construction and controlling mooring system.