Modeling And Simulation Of Electric Propulsion Ship Under Four Sea Conditions

With the development of large-scale,electrified and intelligent ships,as well as the continuous improvement of society’s awareness of green environmental protection,electric propulsion ships have become the mainstream ship type in the future.As the main power equipment of electric propulsion ship,the change of Propulsion motor’s load has a great influence on the navigation safety.In the classical simulation model of integrated electric propulsion system,it mainly uses sudden increase and decrease of 50% the propulsion motor load to judge the reliability and stability of electric propulsion system,ignoring the influence of marine environment factors when the ship is sailing at sea.For example,wind,wave,current,and other external marine environmental disturbance forces affect ship motion and the entire electric propulsion system.The thesis takes the electric propulsion system of the actual ship as the research object,and considers external marine environmental factors to model and simulate the electric propulsion ships under four sea conditions.The main research contents are as follows:(1)According to the ZHONGNENG LNG "CESI GLADSTONE" full scale drawing and data as the basis,and the power supply schematic diagram as reference,the article selects diesel engine and speed regulation system,synchronous generators and excitation system,three-phase uncontrollable rectifier,three-phase asynchronous motor frequency of motor regulated speed control system,propeller and rudder as the research object.The modular idea is used to build the electric propulsion system by simulation software and combine with the external marine environment(wind,waves,currents,etc.)disturbance dynamics model to build a simulation model of electric propulsion ship under four sea conditions.(2)In order to ensure that the electric propulsion system can achieve better simulation result,the control parameters of the model are adjusted and optimized by the particle swarm algorithm and compared with the parameters set by the traditional empirical method.The results show that the control parameters optimized by the particle swarm algorithm can better optimize the overall model control effect compared with the parameters set by the empirical method.(3)The ship’s electric propulsion system under calm sea condition is compared and analyzed with the classical model of sudden static load,the result show the model is correct.Changing the sea conditions of wave disturbance,the propeller shaft power and ship speed curves during the simulation are compared and analyzed with those on the drawings,the results prove that the electric propulsion ship model is reliable under four sea conditions.In addition,the simulation model is built to provide a new method and idea for the modeling of electric propulsion system;it provides a mathematical model for the extension of the laboratory project marine simulator,and provides a reference for the marine testing of real ships in the future shipbuilding.