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Research On Control Strategy For Composite Energy Storage Of Dc Microgrid Based On State Of Charge Balance

Posted on:2021-01-31Degree:MasterType:Thesis
Country:ChinaCandidate:S RenFull Text:PDF
GTID:2392330626955134Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
In recent years,due to the increasing depletion of fossil energy at home and abroad and the increasing problem of environmental pollution,microgrids using clean energy as the energy source have become an inevitable choice to solve the problem of energy shortage and environmental pollution.With the continuous increase of DC load on the distribution network side,the emergence and research of DC microgrids has attracted wide attention around the world.Due to the instability of distributed generation power that is susceptible to natural conditions,it is not conducive to the safe and reliable operation of DC microgrids.As a dispatching resource,the compound energy storage system is the energy buffering link of the DC microgrid,and it is the key to the uninterruptible power supply of the DC microgrid,the smoothing of power fluctuations and reliable operation.This paper focuses on the research of composite energy storage control strategy in DC microgrid.First,this paper introduces the structure and components of a DC microgrid.It focuses on the mathematical models and control principles of photovoltaic cells,lithium batteries,supercapacitors,and interface circuits,and analyzes the MPPT mode of photovoltaic cells.Secondly,the composite energy storage structure is introduced,the advantages and disadvantages of various composite energy storage structures are analyzed,and a control strategy based on DC Bus Signal(DBS)of voltage stabilization is proposed for the composite energy storage structure selected in this paper.This control strategy can automatically adjust the charge and discharge current of the energy storage system according to the magnitude of the DC bus voltage change,and quickly maintain the DC bus voltage stability.In order to limit the over-charge and over-discharge of the energy storage system,the size of the bus voltage change is divided into blocks.An energy management and control strategy in the DC microgrid is proposed,and the energy storage changer is implemented according to the control strategy proposed in this paper.Designed and analyzed the frequency response curve of the designed energy storage converter,and verified the rationality of the designed energy storage converter.Then,based on the DBS control strategy proposed in this paper,a mobile filter control algorithm is used to reasonably allocate the energy between the battery and the supercapacitor,and the SOC imbalance between the battery packs in the traditional control method is proposed.Equilibrium control strategy.This control strategy uses the nature of the exponential function and introduces adjustment factors.The current distribution coefficient is calculated according to the SOC of each battery and the adjustment factor.The output current of the batteries is reasonably distributed.The SOC between battery groups is achieved through current closed-loop control balanced.Finally,this paper selects a composite energy storage system of two sets of storage batteries and a super capacitor,selects the adjustment factor during charging by experiment,and builds a DC microgrid model including the composite energy storage system in MATLAB for composite energy storage.Charge and discharge and SOC balance simulation analysis.The simulation results verify the correctness and rationality of the control strategy proposed in this paper.
Keywords/Search Tags:DC Microgrid, Composite Energy Storage System, Battery, Super Capacitor, SOC Balance
PDF Full Text Request
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