| With the development of national strategy to the deep sea,jack-up offshore platforms are widely used in oil development,wind power installation and offshore ranch operations.They are important equipment for offshore operations.Among them,synchronous lifting control system is an important part of offshore platform,and its performance directly affects the efficiency and safety of platform lifting.Therefore,it is of great significance to study the synchronous lifting control system of four-leg offshore platform.The control strategy and method of synchronous lifting of offshore platform are studied by taking the drive motor in the lifting mechanism of four-leg electric drive offshore platform as the control object.A synchronous lifting control strategy for offshore platform with four legs is proposed,which is coupled with speed and inclination deviation.Based on the analysis of the lifting structure and principle of the relevant offshore platforms,a four leg offshore platform is designed and built according to a certain proportion.The corresponding control system is developed,and the effectiveness of the proposed synchronization control strategy is verified.The main work is as follows:First,analyze the structure and lifting principle of electrically driven four leg offshore platform,and propose a synchronous lifting control strategy for four leg offshore platforms with inclination inclination deviation coupling.This strategy is a composite synchronization control strategy which combines platform dip compensation,parallel synchronization control and deviation coupling synchronization control.Finally,a 40:1scaled-down four-leg marine test platform is designed and built.The single-leg multi-motor drive is simplified to single-motor drive and rack-and-pinion meshing drive.Secondly,a distributed redundancy control structure is adopted to design the overall control scheme of the electric drive four-leg offshore platform.The electrical hardware of PLC and its configuration module,frequency conversion driver,inverse power conversion device,special sensors and communication mode are selected.Finally,a 40:1 scaled-down four-leg marine synchronous control test platform is designed and built.The single-leg multi-motor drive is simplified to single motor drive,and the gear-rack meshing drive.The electrical system of the synchronous control test platform is designed.Third,based on the synchronous control test platform,the corresponding electrical automatic control program is designed,which mainly includes Win CC monitor screendesign,OPC configuration communication,inclination analog acquisition,motor speed detection,parameter adjustment of PID control panel,etc.It is used to verify the speed-inclination deviation coupling synchronous control strategy.Fourthly,three rising tests of the platform,including constant speed,balanced start-up with different inclination angles and speed switching,and the relationship between inclination stability and rising speed,have been completed.The maximum inclination angle of platform rise,convergence time,relationship between platform rise speed and standard deviation of inclination angle in four different situations were analyzed.Verify that the speed-dip deviation coupling synchronous control strategy can control the platform to run smoothly and balance,and get the applicable conditions of the control strategy.The experimental results show that the speed-inclination deviation coupling synchronous control strategy is feasible.The platform balance and stable operation can be controlled when the speed-inclination deviation coupling synchronous control strategy is carried out in the rising test of different scenarios,and the platform inclination angle can be guaranteed within ±0.3° in the end,which meets the requirements of the safe dip angle in the safety regulations for the rise and fall of the shallow sea mobile platform.Thus the validity of the proposed speed-inclination deviation coupling synchronization control strategy is verified. |
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