Research On Synchronous Lifting Control System Of Multi Leg Offshore Platform Based On Improved GPC

The lifting system composed of rack and pinion multi-motors is an important part of the jack-up offshore platform,and its synchronization control performance directly determines the stability and reliability of the offshore platform's lifting process.Due to the large number of controlled motors in the multi-motor lifting system of the offshore platform,problems such as unsuitable motor drive characteristics,inconsistent transmission characteristics from the motor to the controlled object,and load disturbance caused by the deviation of the platform's center of gravity are prone to occur.For such non-linear and strongly coupled systems,the use of conventional control methods can easily cause the platform to overturn and damage key components,which cannot meet the needs of offshore platforms under complex conditions such as lifting.This article starts from the two aspects of multi-motor synchronous control strategy and control algorithm,and studies the synchronous control technology of multi-motor lifting system of jack-up offshore platform to optimize its control structure and improve its synchronization control accuracy.Based on the analysis of the synchronization control requirements for the lifting process of offshore platforms—that is,the high-precision position tracking control of a single motor and the high-precision cluster synchronization control of multiple groups of motors,a ringcoupled synchronization control strategy for multi-motor lifting systems based on predictive control is proposed.Theoretical derivation,simulation calculation and physical experiment verify the effectiveness of the strategy.the main research content and conclusions of the paper are as follows:First,on the basis of simplifying the dynamic structure of asynchronous motor vector control,the closed-loop control system of the multi-motor continuous lifting platform and its corresponding mathematical model are established,and the synchronization control requirements of the multi-motor offshore platform lifting system are analyzed for subsequent synchronization.The design of the compensator controller provides a theoretical basis.Second,in response to the tracking control requirements of the multi-motor lifting system,based on the study of its single-motor high-precision position tracking control algorithm,an improved generalized predictive control algorithm is proposed to improve its single-motor position tracking control performance.The comparative analysis of the traditional Generalized Predictive Control(GPC)algorithm verifies the tracking control effect of the improved predictive control on the multi-motor lifting system of the offshore platform.The simulation results show that the improved generalized predictive control has better fixed value tracking and follow-up tracking performance,has the advantages of small overshoot,fast response,strong anti-disturbance ability and high control accuracy,and can realize real-time tracking control of motor position.Third,in response to the synchronization tracking control requirements of the multimotor lifting system,a control method based on improved generalized prediction and loop coupling strategy is proposed.A unified controlled autoregressive average model with all motors as a whole is established,which simplifies the process of parameter adjustment in traditional control structures;integrates multi-step prediction,rolling optimization and feedback correction ideas in generalized prediction,and designs loop coupling The synchronous predictive controller constructs an optimal performance index function including synchronization error and position tracking error,and theoretically derives its synchronization control law.Through simulation,it is compared with the master-slave PID synchronization control method to verify its effecttiveness.The results show that the control method can accurately track the motion trajectory and improve the transient performance of synchronous tracking.Fourth,build a rack-and-pinion multi-motor platform physical prototype,design and complete a ring-coupled synchronization control method based on generalized predictive control,exchange data with the host computer in real time through OPC,and the platform lifting is monitored.Compared with the traditional master-slave PID method,the actual effect is better than the traditional control method.