Study On Small Signal Stability Of Multi Microgrid Based On Reachability Analysis

With the mature development of distributed power generation technology,large-scale distributed generation access to large power grids in the form of micro-grid.With more and more micro-grid joining into the distribution network and reach a certain scale,it constitutes a multi-micro grid.Multi micro grid is a kind of intelligent operation mode of large scale micro grid,which is composed of a plurality of micro grids which are close to each other.Due to the complexity of the distributed power supply and the special operating characteristics of the microgrid,it is necessary to analyze the stability of the microgrid system with various factors.Therefore,in this paper,based on the small signal stability of multi micro grid,it propose an theoty which studying on the small signal stability of multi-microgrid based on reachability analysis method.In this paper,firstly,a small signal stability analysis model for each component in the microgridis established,which is lay the theoretical foundation for the stability analysis of microgrid.In considering the DG structure itself,it establish a distributed power inverter small signal stability model,including the power droop control model,voltage and current double PI control model and filter circuit model;According to the characteristics of load types,a small disturbance stability model with load disturbances is builded.Finally,on the basis of the micro grid structure,the circuit model is processed,and the whole system small disturbance stability model is established in the common coordinate system.In order to study the influence of the disturbance in the microgrid,this paper presents a small interference stability analysis of the microgrid based on the reachability analysis.According to the characteristics of the uncertainty of the micro-grid line parameters,high proportion distributed power and asymmetrical load,this method use the form of aggregates to express the variable parameters of the system,which can be applied to the small interference stability analysis of the system.The reachability analysis method is used to study the small signal stability of the system due to various factors.Use of the characteristics of a zonotype which contains multi-variable parameter,the value analysis method makes the storage efficiency and greatly improve the computing performance.Finally,an example is given to illustrate the rationality and effectiveness of the proposed algorithm.