Research On Coordinated Control Strategy Of AC/DC Hybrid Microgrid

The AC/DC hybrid microgrid with multiple distributed power sources can simultaneously take advantage of the AC microgrid and the DC microgrid to meet the needs of different loads,reduce energy conversion devices,improve energy conversion efficiency,and provide economical and reliable power supply.The coordinated control problem of multi-distributed power AC/DC hybrid microgrid has become a hot issue in current research.This thesis focuses on the coordinated control technology of AC/DC hybrid microgrid with multi-distributed power supply.Firstly,this thesis introduces the mathematical model of various distributed generation systems in the microgrid and the models of their corresponding grid-connected controllers.At the same time,a DC/DC converter with distributed power supply to the DC bus,a DC/AC inverter connected to the AC bus,and a simulation model of the bidirectional AC/DC converter with the DC microgrid incorporated into the AC bus are established.On this basis,the corresponding operation mode and control mode of the bidirectional AC/DC converter in the grid-connected and isolated mode are studied.Secondly,based on the DC microgrid as the research object,based on the analysis of the hierarchical control defects,the floating power control strategy of DC microgrid is proposed.Then the control strategy is simulated in Matlab,and it is verified that the control strategy can achieve the stability control of the DC microgrid.Taking the AC microgrid as the research object,based on the constant voltage control and the DC voltage control strategy,the AC microgrid coordinated control strategy based on the improved DC voltage control is proposed.Then the control strategy is carried out in Matlab.The simulation proves that the control strategy can achieve stability control of the AC microgrid.Taking the AC-DC hybrid microgrid as the research object,based on the DC microgrid control strategy and the AC microgrid control strategy,a coordinated control strategy for AC/DC hybrid microgrid is proposed.Then the strategy is simulated in Matlab.It is verified that the control strategy can achieve stability control of the AC microgrid.Finally,based on a company’s microgrid demonstration project,The distributed power supply in the hybrid microgrid was chosen.At the same time,the installation and location of the power supply will be explained accordingly.The simulation of the microgrid in the project was carried out.It is verified that the proposed AC/DC hybrid microgrid coordinated control strategy can realize the safe and stable operation of the microgrid in the demonstration project.According to the demonstration project,based on the coordinated control strategy,the corresponding operation and monitoring system of AC/DC hybrid microgrid is designed and developed.Through the trial operation of the system,the feasibility and effectiveness of the proposed strategy are verified.