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Research On Multi-microgrid Grid Technology And Coordinated Control Strategy

Posted on:2018-08-15Degree:MasterType:Thesis
Country:ChinaCandidate:B BaiFull Text:PDF
GTID:2322330518973183Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the transformation of energy structure,micro-grid based on various clean energy sources has been developed rapidly.The micro-grid is composed of distributed generation units,battery energy storage units and the corresponding load,which has the advantages of energy saving,energy optimization and coordinated control.In the meantime,it can run individually or be connected to the grid.However,to meet the needs of large-scale new energy power generation units accessed in and the demand for power quality and reliability of the users,the concept of multi-microgrid which is composed of several sub-microgrids is proposed,so that the sub-microgrids can be untidily managed and coordinated.Therefore,a multi-microgrid system which composed of two sub-microgrids is designed and built in this paper.Moreover,based on different network structure,the studies have been accomplished for the three-level hierarchical control technology,multi-microgrid power sharing,trigger events,state transitions and tie-line power control etc.The main work of this paper is as follows:Firstly,according to the multi-microgrid system of "Key Laboratory of Power Electronics Energy Saving Technology and Equipment" of Xihua university,the mathematical modeling and theoretical analysis of the distributed power generation units(such as wind power generation system,photovoltaic power generation system,diesel power generation system,etc.)and energy storage units have been completed.At the same time,the method of grid-connected control for distributed powers is studied,several common control strategies which combined with the control structure of main circuit are discussed,and mathematical modeling and simulation analysis are carried out according to the basic principles of various control strategies.Moreover,to solve the problem of uneven distribution of reactive power in traditional droop control,a virtual impedance loop is designed and simulated by Matlab/Simulink.Aiming at the shortcomings of the original virtual synchronous generator control,the virtual synchronous generator control strategy based on the PR controller is proposed in this paper,the mathematical modeling and simulation analysis are carried out,and the RT-LAB hardware simulation platform is built to verify the feasibility of the control strategy.Secondly,the design and construction process of multi-microgrid system are described in this paper,then the composition of the distributed generations and the network structure of the micro-grid 1 and the micro-grid 2 are analyzed.Meanwhile,the interconnection mode,triggering event and state switch table of two micro-grids are designed,to realize the serial and parallel network switching and make the study of the coordinated control strategy of different network structures more convenient.In addition,a three-level hierarchical control scheme is designed for the laboratory multi-microgrid system,and the functions of the controllers at all levels are planned.Finally,based on the ARM coordination controller,a coordinated control strategy isdeveloped to realize the power control of the connection line of the multi-microgrid system.Simultaneously,combined with the experimental platform,the synchronos grid-connected and energy complement of multi-microgrid are studied and verified in this paper.
Keywords/Search Tags:multi-microgrid, coordination control, tie-line power control, micro-grid synchronization, power sharing
PDF Full Text Request
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