Parameters Design and Performance Analysis for Grid-tied VSG-Controlled Converters
Because of the high penetration of distributed generation (DG) systems based on renewable energy sources (RES), it is necessary to develop control techniques for improving support to grid frequency and voltage from this kind of generation. Among the solutions proposed in the literature, the virtual synchronous generator (VSG) concept has proven to be an attractive solution to interconnect DG units to the power grid. However, the dynamic behavior of the VSG has not yet been discussed for cases in which line impedance parameters varies in relation to their rated values. To evaluate this issue, in this work a dynamic model of VSG power flow has been derived and its dynamic characteristics discussed. Based on this model, the parameters for VSG controllers are designed by using root-locus method (RLM) in order to realize desired dynamic performance. Then the VSG dynamic performance under line impedance variation eect is assessed. Finally, simulation results demonstrated theoretical analysis and parameters design method.