Study On Control Strategy Of Marine Dual Battery-capacitor And Photovoltaic Hybrid Power System

In recent years,with the shortage of fossil fuels and increasingly serious environmental problems,traditional ships have been unable to meet the requirements of current social development.In order to ensure the rapid and stable development of economy and society,it is urgent to develop environmentally friendly ships.For electric boat,the power battery is one of its key components.At present,most of the pure electric ships sold on the market use batteries as the only energy.Such electric ships have problems such as low power density and short life,which affect the performance of batteries and the sailing range of ships,and hinder the promotion and research of electric ships.Supercapacitors have the advantages of high power density,long life and can supplement the characteristics of batteries,while photovoltaic system can charge the batteries.The three combined into a hybrid power system to provide energy for electric ships,which is of great significance to the research of electric ships.This paper takes the pure electric ship based on hybrid power system as the research object.According to the energy requirements and advantages of the hybrid power system,the duallithium ion battery-ultracapacitor and photovoltaic hybrid power system are designed.One end of two two-way DC/DC converters is connected to the DC bus,and the other end is connected to the lithium ion battery and the ultracapacitor respectively.Another lithium-ion battery is connected to the photovoltaic system and charged.In order to simulate the driving situation of pure electric ship,this paper chooses DC motor as the load part of electric ship,and analyzes the core part of hybrid power supply,DC/DC converter.Bidirectional half-bridge DC/DC converter is selected according to the characteristics of different DC/DC converters.The improved cuckoo-disturbance observation method is used to shorten the time needed for photovoltaic cells to reach the maximum power point.Based on Matlab/Simulink,a hybrid power simulation system for electric ships is established and a fuzzy control strategy and particle swarm optimization fuzzy control algorithm are designed to simulate the driving conditions of electric ships.Simulation tests were carried out according to the load current,the remaining power of lithium ion battery and the remaining power of supercapacitor of the hybrid power system under different working conditions.The results show that the hybrid system combines the characteristics of high specific energy and high specific power,avoids the instantaneous discharge of large current of lithium ion battery,and improves the life of the hybrid system.