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Hybrid Energy Storage Coordinated Control And Energy Management Strategy For DC Microgrid

Posted on:2018-07-15Degree:MasterType:Thesis
Country:ChinaCandidate:K H DuanFull Text:PDF
GTID:2322330542969865Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
The aggravation of energy crisis has promoted the development of renewable energy.However,the output power of solar photovoltaic and wind power generation have strong randomness because of the influence of the environment.Their direct access to the grid will have a serious impact on its stable operation.In order to solve this problem,scholars put forward the concept of micro grid.Based on the background of the DC microgrid composed of the solar photovoltaic power generation system,the super capacitor battery hybrid energy storage system and the load,this paper studys the coordinated control strategy of ultracapacitor-battery hybrid energy storage system of DC microgrid,and analyzes the operation of the system and gives the strategy of energy management in the various modes of operation.The main contents are as follows:Firstly,a practical photovoltaic cell engineering model is established and a simulation model is built in Matlab/Simulink.The correctness of the model is verified by simulation.The traditional perturbation and observer method has defects of steady-state accuracy and dynamic response.For this,a maximum power point tracking strategy based on adaptive variable step disturbance observation method is put forward,and the effectiveness of the algorithm is verified by simulation.In order to ensure the stable operation of photovoltaic power generation system,the maximum power tracking control and costant pressure control are put forward.A simulation platform is built in Matlab/Simulink,and the results show that stable operation of the system can be guaranteed through the reasonable switching of two kinds of control modes.Then,the working principle of the ultracapacitor-battery hybrid energy storage system is deeply studied.Based on this,a coordinated control strategy of hybrid energy storage system is proposed.In order to better play to the advantages of two different types of energy storage devices,this paper uses the super capacitor with fast response speed to response to the high frequency part of the fluctuating power of the system and the dynamic non response power of the battery and uses the battery with high energy density to undertake low frequency part of the fluctuating power in the hybrid energy storage subsystem.A power allocation method based on state of charge(SOC)is proposed combined with the traditional droop control and their SOC between the different subsystems and the parameter design method of bidirectional DC/DC converter of energy storage element is given.A simulation platform is built in Matlab/Simulink,and the effectiveness of the proposed method is verified by simulation.Finally,this paper divides the photovoltaic DC microgrid into regions using the idea of partition management.Based on this,this paper analyzes the power flow state and control target of the DC microgrid with distributed hybrid energy storage under island operation state and two kinds of operation state of regional autonomy and regional assistance are put forward.According to the relationship between the output power of each regional PV and load power as well as the different SOC among energy storage units,the regional autonomy model is specifically divided into four operation modes.The energy management strategy under different operating modes is given and a photovoltaic DC microgrid that contains three multiple regions is built in Matlab/Simulink,and the effectiveness of the proposed method is verified by simulation.
Keywords/Search Tags:Photovoltaic generation, DC microgrid, Hybrid energy storage, Energy management, Coordination control
PDF Full Text Request
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