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Research On Voltage Control Of Wind-solar DC Microgrid

Posted on:2020-06-02Degree:MasterType:Thesis
Country:ChinaCandidate:G X D ShangFull Text:PDF
GTID:2432330575953871Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
As an emerging technology,microgrid can give full play to the advantages of distributed generation,make renewable energy flexible and efficient,and play an active role in the flexible and reliable operation of power systems.DC microgrid has no phase,frequency and reactive power problems.It has a wide range of applications and will become an important development direction in the field of power supply in the future.In particular,islanded DC microgrid provides a new and ideal solution for power supply in remote areas and urban residential areas.Based on the demonstration project of Tianjin key research and development plan"Wind-Solar Complementary Smart Microgrid for Wireless Charging of Electric Vehicles",this dissertation firstly studies and analyses the system characteristics of the isolated island wind-solar-battery DC microgrid,and then studies the power output characteristics of the photovoltaic power generation system,wind power generation and lithium iron phosphate battery in the wind-solar-battery DC microgrid.The corresponding mathematical models are established.Secondly,a coordinated control strategy combining hierarchical control with master-slave control is proposed based on the DC microgrid structure of the demonstration project.The control strategy of the photovoltaic power generation system and the wind power generation system in the microgrid is designed to realize the maximum power tracking function.The DC-DC converter on the energy storage side is set as the main control unit in the master-slave control strategy to maintain the stability of DC bus voltage and suppress the power fluctuation of the microgrid system.The working principle of bi-directional DC-DC converter for energy storage unit is analyzed.Aiming at the unstable characteristics of the output of renewable energy power generation systems such as wind and solar,and the influence of load switching or sudden large fluctuation on the DC bus voltage.A feedforward control strategy is proposed for the bi-directional converter of energy storage system based on the voltage-current double closed-loop proportional integral control to ensure the stability of the converter.On the premise of state characteristics,the response speed of the converter is improved.With the help of the monitoring system of demonstration project,a DC microgrid central controller is designed to coordinate the distributed power supply controller and manage the energy of the whole system.Then,according to the actual capacity of the demonstration project,the simulation model of the wind-solar-battery DC microgrid is built by using the simulation software based on Matlab/Simulink for the proposed coordinated control strategy.The energy management and coordinated control method of the isolated DC microgrid are designed,and the proposed control strategy is simulated and verified.Finally,relying on the "Wind-Solar Complementary Smart Microgrid for Wireless Charging of Electric Vehicles" demonstration project,the experimental verification of the coordinated control strategy proposed in the previous dissertation is carried out,and the experimental results are analyzed.The practicality and effectiveness of the proposed control strategy in engineering practice are proved.The energy management of the DC microgrid system makes it safe and stable.
Keywords/Search Tags:DC microgrid, hierarchical control, master-slave control, feedforward control, energy management
PDF Full Text Request
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