Impact of Synchronous Generator Replacement with VSG on Power System Stability

The stability of frequency and voltage endure high risk due to the integration of power converters. One of the promising solution is the virtual synchronous generator, which controls the power converter to mimic the characteristics of a synchronous generator. This paper evaluates the impact of using the virtual synchronous generator instead of an actual synchronous generator on the power system. Two different modeling methods are considered, where a high order model is used to investigate that how close a virtual synchronous generator can emulate a synchronous generator, and a low order model is used to investigate the influence when only the key features of the synchronous generator are modeled, such as the inertia. The IEEE 9-bus modified test system is used to obtain the simulation results in this paper. It shows that a 6th-order model based VSG is detailed enough to emulate a synchronous generator in most cases and a 2nd-order model based VSG behaves differently, which may introduce both advantages and disadvantages.