Small-Signal Modeling and Analysis of Combination-Configuration Microgrid Based on Droop Control

In order to study the influence of system parameters on the stability and dynamic performance of combination-configuration microgrid based on droop control, small-signal model is established at the point of steady state. By calculating the eigenvalues of state matrix, the small-signal stability of combination-configuration microgrid can be directly analyzed. Based on sensitivity analysis, the key parameters influencing on each eigenvalue are found out. Using root locus method, the ranges of key parameters and their influence on dynamic performance are determined. Analysis result shows the presented method provides the basis for the optimization design of key parameters, and is helpful to improve the stability and dynamics performance of islanding microgrid. Introduction Previous dynamic analysis of microgrid has been carried out, but the presented modeling approaches are all focus on stability issues for an individual inverter under different operation mode, and didn’t consider the interaction of inverters with each other and with network dynamics [1]-[3], So some systematic approaches to modeling islanding inverter-based microgrid by state-space method are presented [4], [5] with difference power sharing method, such as droop control and average-current sharing control. When the state-space model is established, many modern controller design techniques such as pole assignment [6] and eigenvalue sensitivity [7], [8] can be utilized to optimize the stability of microgrid system. For the islanding microgrid of which network is combination-configuration, the small-signal model is established, including three major sub-modules: inverters, network, and loads. Based on the above model, the small-signal models of series-configuration and parallel-configuration microgrid are respectively obtained. Considering the universality of parallel-configuration microgrid in the relevant literatures, the performance of parallel-configuration microgrid is analyzed by the use of sensitivity analysis. The analysis result has certain guiding significance to the design of practical microgrid. Microgrid Configuration