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Research On Hierarchical Control Strategy Of DC Microgrid With Photovoltaic And Storage System

Posted on:2018-01-29Degree:MasterType:Thesis
Country:ChinaCandidate:Y N ZhangFull Text:PDF
GTID:2392330599962490Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the development of society,people has paid more and more attention to the issue of energy crisis and environmental protection.Renewable energy has been widely concerned and promoted because of its characteristics of renewable,green and clean.Microgrid technology is an important part of future intelligent distribution system,which is of great significance to the effective use of renewable energy and sustainable development.Compared with the AC microgrid,there is no frequency stability and reactive power in the DC microgrid system.DC microgrid saves some converter devices and equipment cost and circuit loss can be reduced.DC microgrid can also effectively utilize the distributed power generation.The whole system covers power generation,energy storage system,loads and other sectors.Distributed power generation is intermittent and unstable.How to coordinate all the work in various conditions and to give efficient and stable power supply for the load is the hot spot and difficult problem.A hierarchical control strategy for DC microgrid is designed in this paper and it contains three main parts in all.In the first part,the architecture of DC microgrid system is studied and the mathematical model of photovoltaic cell and energy storage system is established.The topology and characteristics of important converter devices in DC microgrid system are analyzed.The second part presents a hierarchical control strategy based on the system layer and the converter layer and the working mode is divided under different working conditions.The control methods of the controllers are designed.With the simulation,the photovoltaic power generation module,energy storage module,grid converter and whole DC microgrid system are built in the third part.The control methods are simulated and analyzed and get the following conclusions: Under the external conditions change,the photovoltaic power generation module can make full use of distributed power generation and achieve maximum power point tracking control.Battery and super capacitor can be charged and discharged according to the system bus voltage fluctuation and adjust the bus voltage when the system is operating in island.The battery capacity can be restored by the two-stage charging method when the system is in parallel operation.Grid converter can stabilize DC bus voltage and maintain power balance.The feasibility of the hierarchical control strategy is verified by simulation experiments above.
Keywords/Search Tags:DC microgrid, Photovoltaic power generation, Hybrid energy storage system, Hierarchical control
PDF Full Text Request
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