Rwseach On Droop Control Startegy Of Microgrid Based On Adaptive Virtual Impedance

The traditional droop control strategy will produce the uneven distribution of reactive power and the system circulation,which will affect the system performance.Although virtual impedance can improve the distribution of reactive power and circulation of the system to a large extent,it will also have a great adverse impact on the output voltage of the system bus and seriously affect the power quality.Therefore,this paper makes a deep research on the problems of uneven power distribution,large system circulation and bus output voltage drop.This paper first introduces the research background and significance of microgrid,and focuses on the analysis of the research status of microgrid at home and abroad.According to the research status at home and abroad,three control strategies of microgrid research are introduced,and the three control strategies are simply analyzed,leading to the research focus of this paper droop control strategy,and analyzing the research status at home and abroad.This paper first introduces the research background and significance of microgrid,and focuses on the analysis of the research status of microgrid at home and abroad.According to the research status at home and abroad,three control strategies of microgrid research are introduced,and the three control strategies are simply analyzed to analyze the research status at home and abroad.Secondly,the inverter model is modeled and analyzed.Through the theoretical analysis of the droop control strategy,the problems easily caused by the droop control strategy and the causes of each problem are introduced.Secondly,according to the different line impedance,the paper analyzes the power distribution of two parallel inverters,analyzes the relationship between power distribution deviation,circulation and output impedance,and analyzes the voltage and current double closed-loop control system of inverter output impedanceThen,based on the previous analysis of the traditional droop control strategy,the droop control strategy with virtual impedance is studied Although the droop control strategy with virtual impedance can improve the uneven distribution of power and the circulation of the system,it will also produce the new problem of too large drop of output voltage of the micro grid bus.Aiming at these problems in microgrid system,this paper proposes a droop control strategy based on adaptive virtual impedance,which improves the droop control strategy based on virtual impedance,and introduces adaptive virtual impedance instead of fixed virtual impedance.The adaptive virtual impedance value can adjust the resistance value adaptively according to the amplitude change of bus output voltage in real time.Then,the simulation model is established by Matlab/Simulink,which verifies the effectiveness of the proposed adaptive virtual impedance control strategy to improve the system reactive power distribution unevenness,suppress the system circulation and stabilize the bus output voltage amplitude,so as to improve the power supply quality.Finally,the hardware circuit and software flow of the micro grid inverter are designed.The hardware mainly introduces the design of each circuit and the selection of components,and the software mainly introduces the design of program flow chart.