Application Of Real-Time Simulation Technology Of Diesel Engine In Large Ship Propulsion System

In recent years,with the continuous development of modern ships,the propulsion system has put forward higher requirements for power,economy and safety.In order to meet the requirements of various aspects,it is necessary to study the steady-state performance,dynamic performance and ship machine propeller matching of propulsion system under different conditions.With the development of simulation technology,simulation analysis using propulsion system model has become an important way to promote system performance analysis,design and optimization.In addition,on-line monitoring system,fault diagnosis system,marine engine simulator,real ship training system and so on can be developed on the basis of ship propulsion system model.For propulsion system design and optimization,as long as the analysis goal is achieved,the real-time simulation is not emphasized.However,if we continue to develop all kinds of practical real-time simulation systems on the basis of the ship propulsion system model,it has a high demand for real-time simulation.How to meet the requirement of real time has been an important problem in system development.Therefore,it is necessary to build a simulation model of propulsion system and study its real-time performance.In present dissertation,without considering the requirement for real-time simulation,a crank angle model of ship propulsion system is built in MATLAB/SIMULINK simulation environment.The propulsion system model consists of a diesel engine module,a gearbox module,a propeller module,a resistance module of hull,a governor module,a rotation balance module of shaft and moving balance module of a ship.When the diesel engine model is built,intake and exhaust gas through the valves,the instantaneous change in gas composition,the instantaneous change in gas properties and the heat loss by the wall are taken into consideration.The crank angle model of propulsion system is applied to the propulsion system of 76 thousand ton Semi-Submersible Heavy Lift Vessel.The steady-state performance under design condition of the propulsion system is studied.In addition,the dynamic performance of the propulsion system is studied under the transition conditions,such as acceleration of the ship,sudden change of the ship resistance and the change of the pitch ratio.And the accuracy of the propulsion system model is verified by the experimental data and data in references.Although the crank angle model has high accuracy,its simulation speed is too slow.According to the characteristics of crank angle model and neural network model,a neural network model based on the crank angle model is proposed.The influence of the change of resistance characteristics and pitch ratio on the performance of the propulsion system is studied.The simulation results show that the neural network model of ship propulsion system is accurate,provide more parameter information,and the simulation of which is faster.The neural network model can be applied to propulsion system performance research and ship engine propeller matching.In a sense,the simulation speed of the neural network model is faster,which increases the possibility of real-time simulation.Thus,the neural network model lays the foundation for real-time simulation.