| Under the pattern of a changing world, it is the strategic needs of China’s internationalstatus to defend the blue territory and enhance the efforts of the exploration and exploitationof offshore oil and gas resources. It is required by China’s rapid economic development toaccelerate the process of independent research and development of deep-water marineequipment. As the main part of the deep-sea oil and gas exploration, the reliability, accuracy,and economy performance of the semi-submersible platform is far-reaching significance forthe development of offshore oil and gas. For the deepwater marine structures, its operatingenvironment is relatively complex and its demand for positioning is more strict, thus thestate-of-the-art dynamic positioning technology has been widely applied. As the core of thedynamic positioning system, the control system performance of good or bad is directlyrelated to the operating conditions and the accuracy of the dynamic positioning of marinestructures. Therefore, researchs on the dynamic positioning control system has a veryimportant significance.A positioning control system research for a semi-submersible platform equipped withdynamic positioning System was present in this paper by theory and simulation experimentsmethod. Firstly, according to motion and dynamics characters of the platform, the model forlow-frequency linear mathematical model modeling is established.The environment load iscalculated that focus on the calculation of the wave drift force. Referenced to the DNVclassification rules, the hardware and software of deepwater dynamic positioning controlsystem is designed.The composition, structure, hierarchy and function are discussed in detailas well. In the filter design, in order to improve the performance of the Kalman filter based onthe model assumption, the self-correction filter for online identification of high-frequencymotion parameters to correct the low-frequency motion signal is introduced. High frequencymovement of self-correction filter and low frequency Kalman filtering is combined as asynthesis filter. In the controller design, the feed forward compensation is introduced into thesystem to offset the impact of the wind on the motion of the platform. With Linear QuadraticOptimal Control, a control system based on complete dynamic positioning system model isdesigned. Finally, based on the MATLAB simulation platform, fixed-point and directional capabilities of the platform simulation is done, which is in the condition of differentcombinations of environmental conditions for wind, waves, and currents. The results showthat the design of the control system is able to meet the requirements. |
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