Voltage sag ride-through performance of Virtual Synchronous Generator

Virtual Synchronous Generator (VSG) is an inverter control structure that supports power system stability by imitating a synchronous machine. Because of the limitation in inverter power and current, their operation under disturbances should be evaluated and enhanced. In this paper, the VSG unit response to different types of faults at grid side is assessed. Besides, a theoretical analysis that traces the trajectory of state variable of the system during voltage sag is represented to justify the effect of the characteristics of symmetrical and unsymmetrical voltage sags. Knowing the critical characteristics (duration and initial point-on-wave) of each type of voltage sag created by fault, proper measures can be embedded to eliminate the hazardous consequences of voltage sags. Furthermore, three additional controllers for voltage sag ride-through enhancement are implemented and tested by experiments.