Modeling And Simulation Of Marine Electric Propulsion System

In the research process of ship electric propulsion technology,modeling and simulation of ship electric propulsion system is of great significance to reduce test cost and improve test efficiency.In view of the problems of large and complex models and slow operation speed in the simulation research of ship electric propulsion system,the following research is made by taking the electric propulsion system in the form of a dual-motor coaxial connection of a certain type of ship as the research object:Firstly,the structure of a certain type of ship power system is analyzed;Mathematical models and simulation models were established for the prime mover in the generator set,including diesel engine and gas turbine and the corresponding speed regulation system;The 12-phase synchronous rectifier generator and its excitation system were analyzed,and mathematical models and simulation models were established.In Matlab/Simulink,the simulation model of the prime mover and the simulation model of the generator are formed into the simulation model of the generator set.The simulation model of prime mover speed regulation system and the simulation model of generator set are simulated for sudden addition and sudden load reduction,and the simulation response is analyzed in combination with relevant specifications to verify the rationality of using the simulation model of prime mover speed regulation system and generator set simulation model built in this paper for the simulation research of electric propulsion system of a certain type of ship.For the electric propulsion part of a certain type of ship,establish a mathematical model of a twelve-phase asynchronous motor,transform the coordinates to a two-phase rotating coordinate system,use the rotor field-oriented method to realize the control of the twelve-phase asynchronous motor,study the structure and working principle of the inverter and SPWM modulation mode,establish a simulation model of the motor-inverter,and use the controlled voltage source module in Matlab/Simulink to equivalently the inverter part to simplify the simulation model to shorten the simulation time and verify its performance;The torque and power relationship of the two motors in the form of coaxial connection are analyzed,the speed-power sag control is used to realize the load power adjustment of the two motors,and the power distribution effect of the load is verified by starting simulation.The oars characteristics of a certain type of ship are studied,the four-quadrant working characteristic curve of the propeller is fitted,the propeller simulation model is established,the hull resistance and wind,wave and current resistance are studied and the simulation model is established,the influence of complex sea conditions on this type of ship is analyzed,and a complete ship resistance-motor-oars matching model is built on the MATLAB/Simulink simulation platform.The established simulation models are composed of a complete simulation model of the ship’s electric propulsion system,which simulates the direct starting mode of the speed mode and the starting mode of constant power mode under static water sea state and complex sea state,studies its speed,speed,power,thrust,torque and other characteristics,summarizes the relevant laws,proposes a speed-segmented starting method,verifies the simulation results,and gives the applicable ship starting scheme under different working conditions.