A Vector-Fitting Based Stability Analysis of Master-Slave Controlled Microgrid

At present, the research on microgrid stability analysis is concentrated mainly on the microgrid adopting droop control, the microgrid adopting master-slave control is still lack in the thorough research, besides, it is necessary to obtain detailed parameters of each distributed energy source for the nowadays widely used state-space model and impedance model based analysis method, however it is hard to implement in practical engineering. To cope with above-mentioned problem, stability analysis method for vector fitting based master-slave controlled microgrid was proposed, that is, each distributed energy resource was regarded as a black-box model and its frequency response was measured, based on the system topology the system aggregation impedance was calculated, and finally, the vector-fitting technique was utilized to obtain transfer function of aggregation impedance, furthermore, the system stability was analyzed. On MATLAB/Simulink platform a microgrid simulation model was established, and by means of the simulation under grid-connected mode and isolated mode the effectiveness of the proposed method was verified. The influences of the variation of such parameters as line impedance and load parameters on microgrid stability were analyzed. Needing not to obtain detailed internal parameters of the power supply, the proposed method possesses high engineering practicability.