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Research On Multi Time Scale Energy Management Of Active Distribution Network With Multi-microgrids

Posted on:2019-05-10Degree:MasterType:Thesis
Country:ChinaCandidate:B Y ChenFull Text:PDF
GTID:2382330548488412Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
With the continuous development of smart grid,distributed generation will be increasingly connected to the active distribution network in the form of microgrids.Microgrid is playing a pivotal role in the dispatch and operation of active distribution network.The interactive response strategy amongs active distribution network and microgrids needs to be taken full consideration of when focusing on energy management research,and the operating benefits of the microgrid participating in the interaction response should be ensured as well.In this paper,the problem of multi time scale energy management was researched with the research example of the active distribution network containing multi-microgrids.Firstly,a hierarchical and multi time scale energy management framework for the active distribution network which contained multi-microgrids of different quantities and scheduling modes was constructed,which combined the hierarchical control structure and the multi time scale mechanism.As the upper layer,the active distribution network was aimed at the minimum amount of electricity purchase from upper network and the minimum total cost of operation,and a global optimization was carried out every hour.Microgrid as the lower level,completed the local day-ahead optimization per hour aiming at minimizing the minimum total cost of operation and the amount of abandoned wind and light;after which the local in-day optimization was conducted with the objective of minimizing the total adjustment and the load power loss every 15 minutes.Secondly,a multi-time-scale priority scheduling strategy of independent scheduling microgrid was formulated.The local optimization of the independent microgrid would not accept the scheduling instruction from the global optimization of the distribution network layer,which was independently dispatched by microgrid itself.When microgrids opearted in independent grid-connected operation,scheduling strategy was divided into 3 kinds of different optimization schemes according to the quantitative relationship amongs the unit power generation cost of the diesel engine,and the electricity price of buying and selling.In each optimization scheme,a predetermined output of the diesel engine and then the output priority of each micro source and external power was set,after whice the second adjustment power of the diesel engine was determined.When the islanding mode was selected,the output priority of the diesel engine was set higher than that of the storage energy.Thirdly,the energy interaction strategy between coordinated microgrids and active distribution network was formulated.When microgrids at below layer selected to participate in distribution network coordinated scheduling,day-ahead optimization was conducted after receiving the plan of interactive power generated by global optimization of distribution network,then followed by the 15-minute level optimization with the guidance of day-ahead optimization.At the end of the in-day optimization,the state information of each unit of the microgrid must be uploaded to the distribution network.In addition,the energy interaction process between EMS of microgrids and the energy management center of active distribution network was studied.In this process,microgrids would switch between independent and coordinated mode,or they switch between grid-connected and islanded mode.The impact of the different number of coordinated microgrids and the mode switching of microgrids on the energy management of the active distribution network was emphatically analyzed.Finally,an example was employed for verification and analysis.The energy management strategy of active distribution network containing multi-microgrids proposed in this paper was showed to have strong ability of active management for distributed generation,and of improving the utilization efficiency of renewable energy,as well as reducing the loss rate of power supply.The coordinated scheduling with multi microgrids reduces the power purchased from the main grid,and the operation cost of distribution,as well as the peak load.Meanwhile,the operation benefit of microgrids was guaranteed.The different number of coordinated microgrids and the switching mode of them have a great influence on the equivalent load characteristics and operation cost of the active distribution network.
Keywords/Search Tags:active distribution network, microgirds, multi time scale, energy management, mode switching
PDF Full Text Request
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