Stability Analysis of Master-slave Control Based Microgrid via Vector Fitting

As an important supplement to the traditional power grid, microgrid plays an important role in improving the reliability and quality of local power grid. However, the high permeability of new energy generation and power electronic equipment significantly changed the dynamic characteristics of the microgrid, which brings a great threat to the safe operation of power system. Therefore, several stability analysis methods have been proposed. However, these researches mainly focused on droop-controlled microgrids, and there is still a lack of in-depth research on master-slave controlled microgrid. Furthermore, these methods need to obtain the detailed parameters of each distributed energy resource(DER), it is difficult to carry out in practical engineering application. To address the abovementioned problems, this work analyzed the stability of master-slave based microgrid without detailed DER parameter. To this end, the frequency-dependent impedance of DER was measured and a frequency-domain fitting technique known as vector fitting was adopted. The robustness and efficiency of the proposed approach was validated under both grid-connected and isolated modes with time-domain simulation and state-space model.