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Research On Coordinated Control Algorithm And Experiment Of DC Microgrid With Photovoltaic And Storage System

Posted on:2019-05-24Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y LiuFull Text:PDF
GTID:2382330566477003Subject:Master of Engineering
Abstract/Summary:PDF Full Text Request
In recent years,with the rapid development of modern industry,the growing serious environmental problems in society and the increasing demand for energy are prompting people to find clean and renewable distributed energy.In order to make better use of distributed energy,microgrid is established at the historic moment.This paper focuses on the operation and control of the DC microgrid composed of photovoltaic arrays,batteries,supercapacitors and loads.The main contents are as follows:Firstly,this paper describes the background and significance of this research.Furthermore,the basic concept and research status of DC microgrid are also briefly introduced.The mathematical model and running characteristics of PV array are studied.Later,a novel improved incremental conductance method with variable step length is proposed through the study.According to the operation requirements of the system,two control strategies of PV array in the system are set up: MPPT and droop control.The improved method is verified by simulation analysis.The simulation results verify the effectiveness and the superiority of the algorithm.Secondly,the model,working principle and charge discharge characteristics of the battery and supercapacitor are studied respectively.On this basis,the power distribution strategy of the hybrid energy storage device consisting of battery and supercapacitor are selected.The working principle and control strategy of bidirectional DC/DC converter and bidirectional DC/AC converter used are analyzed and discussed in this paper.Thirdly,the problems and shortcomings in the conventional droop control are analyzed,and an improved droop control strategy is proposed.By setting the average flow coefficient,the precision of the current sharing is improved.The modeling and simulation is carried out in Matlab/Simulink,and the simulation results prove the effectiveness of the method.The corresponding hardware platform is built for verification.The hardware results verify the effectiveness of the method.Finally,the structure and control method of DC microgrid are studied.Based on bus voltage signal,a coordinated control strategy of DC microgrid is proposed.Under the MPPT method,power allocation strategy and improved droop control strategy proposed in this paper,the DC microgrid operation is divided into four modes through the bus voltage signal.Also,the working state of each unit in each mode is elaborated in detail.During the operation,switching of each mode is smooth and quickly to ensure the stable of DC micro grid.The modeling and simulation are carried out in Matlab/Simulink,and the simulation results prove the effectiveness of the method.
Keywords/Search Tags:DC microgrid, photovoltaic array, droop control, coordinated control, hybrid energy storage
PDF Full Text Request
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