Research On Power Distribution Strategy For Ship’s Micro-grid Based On Photovoltaic-diesel Generator-battery

With the rapid development of the world economy,the problems of fossil energy exhaustion and environmental pollution are becoming more and more serious.It’s recognized that replacing traditional fossil energy with new energy is one of effective way to solve energy and environmental problems.The ship,as a kind of major transportation equipment for world trade,would consume large amounts of fossil energy,and the problem of environmental pollution caused by shipping must be faced.So how to apply new energy such as solar energy and wind energy to ship is of great practical significance to the development of ship industry.At present,the main use of wind energy in ships is wind sail,and solar energy is mainly used by photovoltaic power generation.However,only relying on new energy such as solar energy could not meet the requirement of ship power system.The ship’s micro grid is constructed by increasing diesel generator set and the energy storage system.Due to the variety types of power sources and the different output power characteristics,and in order to realize the stable and reliable power supply of the ship’s micro grid in different working conditions,it is necessary to develop the power distribution strategy for reasonable scheduling of each power source.Therefore,aiming to the ship’s micro grid that consists of diesel generator,photovoltaic cells and lithium battery,this paper focus on improve the utilization rate of renewable energy and prolong the service life of the equipment in the static situation and reduce the frequency fluctuation of the system under dynamic situation by studying the corresponding power distribution strategy.The concrete research content is as follows:Firstly,according to the working principle of diesel generator,photovoltaic cells and lithium battery,the mathematical model is deduced,and the simulation model are built in Matlab/Simulink simulation environment.Secondly,the control strategy of inverter interface model is built and simulated.According to the output characteristics of micro sources and the operation requirements of micro grid,Droop control and PQ(constant power)control are adopt.Based on the working principle of PQ control and Droop control is analyzed,two kinds of control strategies are established and simulated.Then,a power distribution strategy is proposed for ship’s micro grid based onphotovoltaic-diesel generator-battery.In the static case,the operation mode of micro grid is divided into two operating modes:photovoltaic-battery operation mode and photovoltaic-diesel generator-battery operation mode,and the output power of each micro power supply in two operation modes is reasonably planned.The influence mechanism of the frequency change of micro-grid system is studied with load mutation in the photovoltaic-diesel generator-battery operation mode,and a dynamic energy scheduling strategy of micro grid system with current compensation and fuzzy control is presented.The energy scheduling strategy of energy storage system is designed to realize power distribution in static and dynamic situations.Finally,the whole ship’s micro grid simulation system is built based on the simulation model of micro power and inverter.The static power distribution strategy and dynamic power allocation strategy are simulated and verified.