Improved state-space model and analysis of islanding inverter-based microgrid

Based on the traditional modeling method of the inverter-based microgrid, this paper makes some improvement on the state-space model to describe the microgrid more precisely. The coupling item, variation of common rotating angle, in the state-matrix of inverters model introduced by the common rotating reference frame are considered, which isn´t simplified as the inverters individual part as before. Stability analysis based on the eigenvalues of the microgrid improved statespace system model is made, which indicate the frequency and damping of oscillatory components in the transient response. The participation matrix is introduced to identify the relation between the eigenvalues and the state-variables and to find out the most valuable state-variables for certain eigenvalues, which will helpful to improve the microgrid system stability and reduce the order of the system. Simulation and experiment results are carried out based on a three 100 kW inverter based microgrid to verify the corresponding results obtained from the improved model.