Transient Behavior Analysis of VSG-IIDG During Disturbances Considering the Current Limit Unit

The virtual synchronous generator (VSG) is of good prospect for the application of inverter-interfaced distributed generator (IIDG). Similar to conventional synchronous generators, power-angle instability of the VSG-IIDG may occur during faults. However, current studies generally adopt a simplified model and ignore the influence of voltage regulation and current limit in the VSG control. This paper studies the transient behavior mechanism of the VSG-IIDG based on the power-angle characteristics with and without current saturation. The terminal voltage fluctuation of the IIDG due to the voltage regulation of VSG control is also taken into consideration. The typical instabilities and their mechanism are revealed based on different operation conditions. The analysis is verified by simulations based on PSCAD/EMTDC.