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Research On Modular Grid-connected Interface Converters In Photovoltaic Generation System

Posted on:2013-02-27Degree:MasterType:Thesis
Country:ChinaCandidate:T J WuFull Text:PDF
GTID:2232330362470725Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
Distributed dc power supply systems can improve the utilization efficiency of new energy, andprovide high quality and stable reliable dc power energy to modern electronics and electrical devices.In recent years, with the further development of new energy sources and dc power supply system, dcmicrogrid has been proposed and received international attention by many research institutions. Thedc microgrid is better to connect with the new energy and reduces the conversion loss by leaving outDC/AC and DC/AC converters.In the dc micro-grid, a bi-directional DC/AC converter is usually used to connected dc bus withthe AC utility. The bi-directional DC/AC converter lets the dc microgrid and AC utility grid supportwith each other and mutually redundant, regulates the dc bus voltage first, and decouples the ACutility grid and dc bus. And the modular structure is conducive to simplify the system thermal design,reduce the electrical stress of power devices, achieve redundant power supply for multi-modules, andimprove system extendibility.In this paper, the modular bi-directional DC/AC converters in Photovoltaic Generation Systemare researched in details. The problem of inconsistent power flow in parallel multiple modularbi-directional DC/AC converters with conventional control method is analyzed. The inherentrelationship between system operating status and the trend of the dc bus voltage is researched, and animproved control strategy for the modular bi-directional DC/AC converters in parallel operation isproposed. Power flowing of inversion and rectification is distinguished naturally by different dc busvoltages. At the same time, the seamless switching between inversion and rectification is realized. Inaddition, the proposed control method for modular bi-directional DC/AC converter in paralleloperation can also be used for the modular three-phase bi-directional DC/AC converters, and a simpleanalysis is in this paper.The prototype is built and the designs of the main power parameters, control circuits andsoftware are given out in this paper. Besides, the experimental results are presented and the resultsshow that the consistent power flow of each module and the seamless switching between inversionand rectification are all realized.
Keywords/Search Tags:bi-directional DC/AC converter, grid-connected, modular, parallel, photovoltaic (PV)generation, dc microgrid/dc power supply system
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