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Research On Coordinated Control Of PV DC Microgrid

Posted on:2018-03-10Degree:MasterType:Thesis
Country:ChinaCandidate:J W LiuFull Text:PDF
GTID:2322330542480157Subject:Pattern Recognition and Intelligent Systems
Abstract/Summary:PDF Full Text Request
Due to widespread use of fossil fuels,environmental problems and resource shortage are becoming increasingly severe.People shift their attentions to DC microgrid,for its cleanness,zero pollution.High energy efficiency,low energy loss and strong control ability.Because of small capacity and randomness,the DC voltage is easy to fluctuate when being influenced by the external environment.Therefore,it is necessary to design a suitable energy coordination control algorithm,as a manner to improve the stability of the bus voltage.This paper aims to study DC microgrid energy coordination control strategy by PV microgrid as the control by placing PV microgrid as research object.First of all,this paper discusses the significance of the research,summarizes the current research situation at home and abroad,and analyzes the common structure of DC microgrid.The modeling and characterization of PV cells and battery in DC microgrid are analyzed,and the battery DC/DC converters of PV boost converters and battery are introduced.Secondly,the principle of droop control and the shortcoming of traditional droop control are analyzed.The paper puts forward the coefficient droop control for PV cells and battery.The voltage of the bus can be stabilized when the system changes in the working environment.Moreover,a voltage hierarchical control scheme is proposed,which only manages the energy flow in the DC microgrid only through the bus voltage,so that the various parts of the DC microgrid can smooth switching,and make the DC microgrid system bus voltage stability and energy balance.Finally,a simulation model was built in MATLAB/Simulink environment,the proposed method of hierarchical control of dc microgrid,the coefficient droop control for PV cells and battery are simulated and verified.The simulation results shows that,the battery and the load can be used to coordinate operation by the hierarchical control,and the DC microgrid can realize the smooth switching between the three working modes.The coefficient droop control for battery can improve the precision of the bus voltage control.The control method of the coefficient droop control for PV cells not only achieve the load balance,but also keep the bus voltage stable to the rated value and meet the demand of the DC microgrid.
Keywords/Search Tags:DC microgrid, variable coefficient droop control, voltage hierarchical control
PDF Full Text Request
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