Study On Modeling And Control Strategy Of Ship-to-shore Power Conversion System For Ships

It is an important measure to promote the use of shore power in the port of the ship,which is an important measure for the development of green port construction in the country.However,the problems that the power loss of the whole ship is easy to occur when the power supply of the ship’s power supply switch and the output of the shore power system is not guaranteed hindered the technology promotion of shore power.In view of these problem,that structural and control strategy of the electricity system across the bank should be studied.Frequency conversion equipment is the core equipment of shore power system and the main control object of shore power control system.The inverter control strategy has a direct effect on the power output of the power system.In the control strategy of the inverter,the droop control can control the inverter easily and efficiently,and the voltage and frequency of its output have the droop characteristic,which satisfies the need of no gap connection with the ship grid.Therefore,the shore power system is a control object,based on the voltage current double closed loop control theory,and the control system of the rectifier and the inverter is designed in deeply studied downward control strategy.In the meantime,to make sure that the power of the shore power output is stable,it is optimized for the control system based on virtual inertial and self-containment technology.The simulation experiment was carried out on MATLAB/Simulink platform,and the experimental results were analyzed to provide certain reference value for the study of the control strategy of shore power system.First,the physical structure of shore power system is studied.According to the current model of ship shore power system,the power supply mode and electric configuration scheme of shore power system are summarized.For the unified shore power design scheme,this paper puts forward the improvement idea of shore power system structure,and reduces the difficulty of controlling the output voltage of the electric system across the ship.At the same time,the function of each component of the system is analyzed,and the type of frequency conversion equipment is described,and the appropriate frequency conversion equipment is selected according to the system requirements.Then,based on the physical structure of the selected equipment,the mathematical model of the frequency conversion equipment is established,and the voltage and current double closed-loop control principle of the rectifier and inverter is studied.The control system structure of the inverter is analyzed,and the reverse order of the control signal of the inverter is studied,and the space voltage vector modulation technology(SVPWM),droop control principle and power calculation method are studied in turn.According to the above principle,the corresponding controller is designed and the simulation analysis is carried out to verify the correctness and effectiveness of the control model.Lastly,in accordance with that feature of ship’s power system,the application of the droop control and voltage current double closed loop control in the ship shore electric system is applied,the virtual inertial links and the auto-immunity control are respectively added in the droop control module and the voltage current double closed loop module,the control strategy of the system is optimized,the quality of the output power of the shore power system and the suitability of the ship power system are improved.On the MATLAB/Simulink platform,the simulation model of the ship power grid and shore power no-gap conversion system was built,and the ship power grid and shore power and off-grid simulation experiment were carried out according to the actual situation.The synchronization process and load transfer process are analyzed to verify the effectiveness of the control strategy.