Influence Of Micro-source Automatic Splitting And Input Of Micro-source Inverter System In Series Micro-grids

Photovoltaic,wind and other micro-source are easily affected by the external natural conditions due to randomness and uncertainty.When the micro-source output is limited or fails,it needs to solve operation,and the output must be restored after the fault is removed.The micro-grids has small inertia and easily oscillates due to disturbance.Therefore,the micro-source splitting and input will inevitably affect the response of the micro-source inverter system in series micro-grids.For this reason,this thesis mainly studies the influence of automatic splitting and input of microsource on the small signal stability of series micro-grids system.Firstly,a small signal model of the series micro-grids system in isolated island mode is established,including the series inverter with control system model,which adopts the series micro-source inverter link voltage loop and current loop control method,and load model.By calculating the eigenvalues of the coefficient matrix of the model,we can directly analyze the small signal stability of the series micro-grids with micro-source splitting and input,and the influence of the parameters caused by the micro-source splitting and input on the small signal stability in the series micro-grids.At the same time,the impact of micro-source number changes of the series micro-grids are analyzed when taking the small signal model of series inverter phase as the research object.Secondly,a small signal model of micro-source inverter system in gridconnected series micro-grids is established,including the series connection model,power controller model,current controller model,load and network model.The eigenvalue analysis method is used to analyze the state matrix of small signal model of micro-source inverter system in grid-connected series micro-grids.The eigenvalue sensitivity is used to study the effect of different parameters on the eigenvalues,and the variation of the eigenvalues of the small signal model of the series inverters is analyzed when the number of micro-sources are changed.Finally,based on the above theoretical research,a four micro-source series micro-grids system simulation model is built by MATLAB/Simulink software to verify the correctness of the small signal model of the series micro-grid system in islanding and grid-connected mode.Based on the analysis of the output characteristics of the series micro-grid,the correctness of the theoretical analysis of the system when the micro-source splitting and input is verified.