Research On A Hybrid AC/DC Microgrid Architecture Based On MMC-SST With Its Comprehensive Control Strategy

Hybrid AC/DC microgrid synthesize the characteristics of AC microgrid and DC microgrid.It can make the most of a variety of different types of distributed generation,meet the needs of different load.Existing hybrid AC/DC microgrid structure of the distributed power through their respective grid inverter distributed access to distribution network,leading to complex system structure,the high access costs,difficult and inefficient control management.It is not conducive to coordination optimization system and limiting its large-scale application.In view of this,this paper proposes a novel hybrid AC/DC microgrid architecture based on MMC-SST,and a suitable for this kind of structure system of integrated control strategy are designed.Firstly,to comprehensively solve the power quality problems in medium or high voltage distribution network,a new MMC-SST topology and its control strategies are proposed in this paper.The control strategies of MMC-SST input-,isolation-and output-stage are designed in order to achieve the power quality comprehensive management of distribution network.In order to verify the effectiveness of this method,the system simulation model is established by using MATLAB/Simulink.The simulation results indicate that the proposed MMC-SST and control strategies can effectively solve the power quality problems in high voltage distribution networks.Secondly,to overcome the limitation of the existing control strategies of SST,a new kind of dual-loop control structure is developed by combining the IMC current inner loop and proportional integral(PI)voltage outer loop together,according to the characteristics of IMC.By means of this control method,a faster transient response and strong anti-disturbance performance can be obtained.Further,the decoupling control problem under two phase rotating coordinate is avoided,which effectively reduces the complexity of control system.In order to verify the effectiveness of this control method.In order to verify the effectiveness of this control method,the system simulation model is established by using MATLAB/Simulink.Results show that the internal model control based MMC-SST can run stable under the required power factor,and the good performances such as fast voltage and current response speed,strong anti-disturb ability to load,and enhanced robustness on system operation are demonstrated.Finally,a novel hybrid AC/DC microgrid architecture based on MMC-SST,and the control method of the grid connected operation mode,islanding operation mode and STATCOM mode are designed.In order to verify the proposed new ac/dc micro network topology and control strategy is effective,a simulation platform of hybrid AC/DC microgrid based on MMC-SST is established by Matlab/Simulink.The grid connected operation mode,islanding operation mode and STATCOM mode are simulated,simulation results verify the feasibility and effectiveness of the proposed architecture and its comprehensive control strategy.